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Measures as amended, taking into account amendments up to National Environment Protection (Assessment of Site Contamination) Amendment Measure 2013 (No. 1)
Administered by: Agriculture, Water and the Environment
Registered 03 Jun 2013
Start Date 16 May 2013

Commonwealth Coat of Arms

National Environment Protection (Assessment of Site Contamination) Measure 1999

as amended

made under section 14(1) of the

National Environment Protection Council Act 1994 (Cwlth), the National Environment Protection Council (New South Wales) Act 1995 (NSW), the National Environment Protection Council (Victoria) Act 1995 (Vic), the National Environment Protection Council (Queensland) Act 1994 (Qld), the National Environment Protection Council (Western Australia) Act 1996 (WA), the National Environment Protection Council (South Australia) Act 1995 (SA), the National Environment Protection Council (Tasmania) Act 1995 (Tas), the National Environment Protection Council Act 1994 (ACT) and the National Environment Protection Council (Northern Territory) Act 1994 (NT)

Compilation start date:                     16 May 2013

Includes amendments up to:            National Environment Protection (Assessment of Site Contamination) Amendment Measure 2013 (No. 1)

This compilation has been split into 22 volumes

Volume 1:       sections 1-6, Schedules A and B

Volume 2:       Schedule B1

Volume 3:       Schedule B2

Volume 4:       Schedule B3

Volume 5:       Schedule B4

Volume 6:       Schedule B5a

Volume 7:       Schedule B5b

Volume 8:       Schedule B5c

Volume 9:       Schedule B6

Volume 10:     Schedule B7 - Appendix 1

Volume 11:     Schedule B7 - Appendix 2

Volume 12:     Schedule B7 - Appendix 3

Volume 13:     Schedule B7 - Appendix 4

Volume 14:     Schedule B7 - Appendix 5

Volume 15:     Schedule B7 - Appendix 6

Volume 16:     Schedule B7 - Appendix B

Volume 17:     Schedule B7 - Appendix C

Volume 18:     Schedule B7 - Appendix D

Volume 19:     Schedule B7

Volume 20:     Schedule B8

Volume 21:     Schedule B9

Volume 22:     Endnotes

 

Each volume has its own contents

 

 

 

About this compilation

The compiled instrument

This is a compilation of the National Environment Protection (Assessment of Site Contamination) Measure 1999 as amended and in force on 16 May 2013. It includes any amendment affecting the compiled instrument to that date.

This compilation was prepared on 22 May 2013.

The notes at the end of this compilation (the endnotes) include information about amending Acts and instruments and the amendment history of each amended provision.

Uncommenced provisions and amendments

If a provision of the compiled instrument is affected by an uncommenced amendment, the text of the uncommenced amendment is set out in the endnotes.

Application, saving and transitional provisions for amendments

If the operation of an amendment is affected by an application, saving or transitional provision, the provision is identified in the endnotes.

Modifications

If a provision of the compiled instrument is affected by a textual modification that is in force, the text of the modifying provision is set out in the endnotes.

Provisions ceasing to have effect

If a provision of the compiled instrument has expired or otherwise ceased to have effect in accordance with a provision of the instrument, details of the provision are set out in the endnotes.

 

 

  

  

  


 

 

National Environment Protection (Assessment of Site Contamination) Measure 1999 National Environment Protection (Assessment of Site Contamination) Measure 1999 National Environment Protection (Assessment of Site Contamination) Measure 1999 National Environment Protection (Assessment of Site Contamination) Measure 1999 National Environment Protection (Assessment of Site Contamination) Measure 1999 National Environment Protection (Assessment of Site Contamination) Measure 1999 National Environment Protection (Assessment of Site Contamination) Measure 1999 National Environment Protection (Assessment of Site Contamination) Measure 1999 National Environment Protection (Assessment of Site Contamination) Measure 1999 National Environment Protection (Assessment of Site Contamination) Measure 1999 National Environment Protection (Assessment of

Schedule B3

GUIDELINE ON

Laboratory Analysis of Potentially Contaminated Soils

 

 

 

 

PRECAUTIONARY CAVEAT 
This guideline refers to methods of analysis that may require the use of hazardous materials, operations and equipment. It does not, however, address all of the associated real or potential safety problems. It is the responsibility of the user of these guidelines to establish adequate health and safety practices such as those outlined in AS 2243 Safety in laboratories, Parts 1-10 as amended (available online at http://www.standards.com.au), and to ensure that any person involved in performing any relevant procedures is adequately trained and experienced. 

DISCLAIMER 
Any equipment or materials that meet stated specifications and result in satisfactory method performance may be used to carry out the methods referred to in this guideline. Mention of specific trade names, products or suppliers does not constitute endorsement by NEPC of those items, materials, or suppliers over other suitable products or sources. Rather, it is intended to provide users with examples of suitable products and information on those sources that are known to NEPC.

 

 

 

 

Explanatory note
The following guideline provides general guidance in relation to investigation levels for soil, soil vapour and groundwater in the assessment of site contamination.
This Schedule forms part of the National Environment Protection (Assessment of Site Contamination) Measure 1999 and should be read in conjunction with that document, which includes a policy framework and assessment of site contamination flowchart.

It aims to ensure accuracy and precision in analytical results from the laboratory analysis of potentially contaminated soils. It should be read in conjunction with Schedule B2 of the NEPM. 

The original Schedule B3 to the National Environment Protection (Assessment of Site Contamination) Measure 1999 has been repealed and replaced by this document.
The National Environment Protection Council (NEPC) acknowledges the contribution of a number of individuals and organisations towards the development of these guidelines. In particular, these include Environment Protection Authority (EPA) Victoria (principal author), members of the Environmental Laboratories Industry Group (ELIG), other individual staff members of commercial and government laboratories, members of the Australian Contaminated Land Consultants Association (ACLCA) and individual contaminated site consultants, environmental auditors, officers of the NSW Environment Protection Authority and CRC CARE.


Contents
Laboratory analysis of contaminated soil
                                                                                       Page

 

1                             Introduction                                                    1

1.1             Audience                                                                                      1

1.2             Exclusions                                                                                    1

1.3             Schedule structure                                                                      1

2                             Laboratory analysis of potentially
contaminated soil                                           
2

2.1             Scope                                                                                            2

2.2             Determinative methods                                                              2

2.3             Philosophy of methods selected                                                 2

2.4             Referenced methods and use of alternative methods              3

2.5             Screening tests                                                                             4

2.6             Confirmation of organic compounds (for non-specific
techniques)                                                                                 
4

2.7             Leachability and bioavailability                                                4

2.8             Use of laboratory results                                                            5

3                             Quality assurance and quality control           6

3.1             Definitions                                                                                   6

3.2             Method validation                                                                       6

3.2.1                Accuracy                                                                          7

3.2.1.1                 Percent recovery                                                                          7

3.2.2                Precision                                                                           8

3.2.2.1                 Repeatability                                                                                 8

3.2.2.2                 Reproducibility                                                                             8

3.2.2.3                 Confidence limit  and confidence interval                             8

3.2.3                Limits of detection and reporting                                    8

3.2.3.1                 Method detection limit                                                                8

3.2.3.2                 Limit of Reporting                                                                       9

3.3             Laboratory Batch QC procedures                                            9

3.3.1                Process batch and QC interval                                        9

3.3.2                Method blank                                                                   9

3.3.3                Laboratory duplicate analysis                                         9

3.3.4                Laboratory control sample                                           10

3.3.5                Matrix spikes                                                                 10

3.3.6                Surrogate spikes (where appropriate)                          10

3.3.7                Internal standards (where appropriate)                       11

3.4             Documentation of validation and QC procedures                 11

3.5             Field duplicate and secondary duplicate (split) samples        12

3.5.1                Field duplicate                                                                12

3.5.2                Secondary duplicate                                                       12

3.5.3                Replicates for volatile organic compound analysis       13

4                             Sample control, preparation and storage    14

4.1             Sample preparation – general principles                                14

4.2             Sample preparation: non-volatiles and semi-volatiles            14

4.2.1                Separation and removal of extraneous (non-soil)
components                                                                   
14

4.2.2                Homogenising (for non-volatile constituents)               15

4.2.3                Preparation of field-moist (‘as received’) analysis
portions                                                                         
15

4.2.4                Preparation of dry analysis portions (non-volatiles
only)                                                                              
16

4.2.4.1                 Sample drying                                                                             16

4.2.4.2                 Grinding of dry sample                                                            16

4.2.4.3                 Sieving                                                                                          17

4.2.4.4                 Partitioning of dry samples to obtain representative
analysis portions                                                                       
17

4.2.4.5                 Equipment cleaning during sample preparation
(including grinding, sieving and homogenising
procedures)                                                                                 
17

4.2.5                Sample Preparation Summary - Non-volatiles and
semi-volatiles                                                                 
18

4.3             Volatile analytes - sample collection and preparation          19

4.3.1                Sample collection                                                           19

4.3.2                Preliminary screening analysis                                      20

4.4             Sample storage                                                                          20

4.4.1                Holding Times                                                                21

4.5             Documentation and reporting                                                 23

4.5.1                Sample receipt report                                                    23

4.5.2                Analytical report                                                           23

5                             Analytical methods                                       25

5.1             Method selection                                                                       25

6                             Physicochemical analyses                              26

6.1             Soil moisture content                                                                26

6.1.1                Scope and application                                                    26

6.2             Soil pH                                                                                       26

6.2.1                Scope and application                                                    26

6.2.2                Principle                                                                         26

6.3             Electrical conductivity                                                              27

6.3.1                Scope and application                                                    27

6.3.2                Principle                                                                         27

6.4             Cation exchange capacity and exchangeable cations            27

6.4.1                Scope and application                                                    27

6.4.2                Principle                                                                         28

6.5             Water-soluble chloride                                                             28

6.5.1                Scope and application                                                    28

6.5.2                Principle                                                                         28

6.5.3                Interferences                                                                  28

6.6             Organic carbon                                                                         28

6.6.1                Scope and application                                                    28

6.6.2                Interferences                                                                  28

7                             Metals                                                            29

7.1             Aqua regia digestible metals                                                    29

7.1.1                Scope and application                                                    29

7.1.2                Principle                                                                         29

7.2             Acid digestible metals in sediments, sludges and soils            29

7.2.1                Scope and application                                                    29

7.2.2                Principle                                                                         29

7.2.2.1                 For FAAS and ICP-AES                                                          30

7.2.2.2                 For GFAAS and ICP-MS                                                         30

7.3             Metals by microwave assisted acid digestion of
sediments, sludges, soils and oils                                             
30

7.3.1                Scope and application                                                    30

7.3.2                Principle                                                                         30

7.4             Mercury                                                                                     30

7.4.1                Scope and application                                                    30

7.4.2                Principle                                                                         30

7.5             Hexavalent Chromium                                                             31

7.5.1                Scope and application                                                    31

7.5.2                Principle                                                                         31

8                             Halides                                                           32

8.1             Bromide                                                                                     32

8.1.1                Scope and application                                                    32

8.1.2                Principle                                                                         32

8.2             Fluoride                                                                                     32

8.2.1                Scope and application                                                    32

8.2.2                Principle                                                                         32

9                             Non-metals (cyanide and sulfur)                  33

9.1             Cyanide (weak acid dissociable)                                              33

9.1.1                Scope and application                                                    33

9.1.2                Principle                                                                         33

9.2             Total sulfur                                                                               33

9.2.1                Scope and application                                                    33

9.2.2                Principle                                                                         33

9.3             Sulfate                                                                                        33

9.3.1                Scope and application                                                    33

9.3.2                Principle                                                                         34

9.4             Sulfide                                                                                        34

9.4.1                Scope and application                                                    34

9.4.2                Principle                                                                         34

10                          Organics                                                        35

10.1          Volatile organics                                                                       35

10.1.1             Scope and application                                                    35

10.1.2             Monocyclic aromatic hydrocarbons                             36

10.1.2.1               Preliminary screening                                                              36

10.1.2.2               Sample extraction                                                                      36

10.1.2.3               Sample clean-up                                                                         36

10.1.2.4               Sample analysis                                                                          36

10.1.3             Volatile halogenated compounds (VHC)                       36

10.1.3.1               Sample extraction                                                                      37

10.1.3.2               Sample clean-up                                                                         37

10.1.3.3               Sample analysis                                                                          37

10.1.4             Miscellaneous volatile organic compounds                   37

10.1.4.1               Scope                                                                                             37

10.1.4.2               Sample extraction                                                                      38

10.1.4.3               Sample clean-up                                                                         38

10.1.4.4               Sample analysis                                                                          38

10.1.5             Total recoverable hydrocarbons - volatile                   38

10.1.5.1               Scope                                                                                             38

10.1.5.2               Sample extraction                                                                      38

10.1.5.3               Extract clean-up                                                                         39

10.1.5.4               Extract analysis                                                                          39

10.2          Semi-volatile organics                                                               39

10.2.1             Scope and application                                                    39

10.2.2             Semi-volatile chlorinated hydrocarbons                       39

10.2.2.1               Sample extraction                                                                      39

10.2.2.2               Extract clean-up                                                                         40

10.2.2.3               Extract analysis                                                                          40

10.2.3             Polycyclic aromatic hydrocarbons by solvent
extraction                                                                      
40

10.2.3.1               Scope and application                                                               40

10.2.3.2               Sample extraction                                                                      41

10.2.3.3               Sample clean-up                                                                         41

10.2.3.4               Extract analysis                                                                          42

10.2.4             Polycyclic aromatic hydrocarbons by supercritical
fluid extraction                                                              
42

10.2.4.1               Sample extraction                                                                      42

10.2.4.2               Extract clean-up                                                                         42

10.2.4.3               Extract analysis                                                                          42

10.2.5             Organochlorine pesticides and polychlorinated
biphenyls                                                                       
43

10.2.5.1               Scope and application                                                               43

10.2.5.2               Sample extraction                                                                      43

10.2.5.3               Extract analysis                                                                          44

10.2.6             Organophosphorus pesticides                                        44

10.2.6.1               Scope and application                                                               44

10.2.6.2               Sample extraction                                                                      44

10.2.6.3               Extract clean-up                                                                         45

10.2.6.4               Sample Analysis                                                                         45

10.2.7             Total recoverable hydrocarbons                                   45

10.2.8             Total recoverable hydrocarbons by solvent extraction 46

10.2.8.1               Scope                                                                                             46

10.2.8.2               Sample Extraction                                                                     47

10.2.8.3               Extract clean-up                                                                         47

10.2.8.4               Extract Analysis                                                                         47

10.2.9             Phenols                                                                           48

10.2.9.1               Scope and application                                                               48

10.2.9.2               Sample extraction                                                                      48

10.2.9.3               Extract clean-up                                                                         49

10.2.10          Chlorinated herbicides                                                   49

10.2.10.1             Scope and application                                                               49

10.2.10.2             Sample extraction                                                                      49

10.2.10.3             Extract clean-up                                                                         49

10.2.10.4             Extract analysis                                                                          50

10.2.10.5             Extract analysis                                                                          50

10.2.11          Phthalate esters                                                              50

10.2.11.1             Scope and application                                                               50

10.2.11.2             Sample extraction                                                                      50

10.2.11.3             Extract clean-up                                                                         51

10.2.11.4             Extract analysis                                                                          51

10.2.12          Dioxins and furans                                                         51

10.2.12.1             Scope and application                                                               51

10.2.12.2             Sample extraction                                                                      51

10.2.12.3             Extract clean-up                                                                         52

10.2.12.4             Extract analysis                                                                          52

11                          Leachable contaminants                               53

11.1          Scope and application                                                              53

12                          Bibliography                                                 55

13                          Appendix 1: Determination of total
recoverable hydrocarbons (TRH) in soil     
62

13.1          Volatile (C6 – C10) and semi-volatile (>C10-C40) TRH           62

13.1.1             Quality control considerations                                      62

13.1.2             Method validation                                                          63

13.1.2.1               Hydrocarbon product linearity                                              63

13.1.2.2               Product standard reference materials                                  63

13.1.2.3               Proficiency studies                                                                     63

13.2          Method A1: Determination of volatile
TRH: TRH C6 – C10                                                                
63

13.2.1             Scope and application                                                    63

13.2.2             Limitations                                                                     63

13.2.3             Interferences                                                                  64

13.2.4             Principle                                                                         64

13.2.5             Method                                                                           64

13.2.5.1               Apparatus                                                                                     64

13.2.5.2               Reagents and standards                                                            64

13.2.5.3               Procedure                                                                                     65

13.2.6             GC Analysis                                                                   65

13.2.6.1               Calibration                                                                                  65

13.2.6.2               Measurement of test sample                                                    66

13.2.7             Calculations                                                                   66

13.2.7.1               Integration of peaks                                                                  66

13.2.7.2               Calculation of vTRH (C6 – C10) content                                66

13.3          Method A2: Determination of semi-volatile
TRH: TRH >C10 – C40                                                             
66

13.3.1             Scope and application                                                    66

13.3.2             Limitations                                                                     67

13.3.3             Interferences                                                                  67

13.3.4             Principle                                                                         67

13.3.5             Method                                                                           67

13.3.5.1               Apparatus                                                                                     67

13.3.5.2               Reagents and standards                                                            67

13.3.5.3               Procedure                                                                                     68

13.3.5.4               Silica gel clean-up                                                                      68

13.3.6             GC analysis                                                                    69

13.3.6.1               GC conditions                                                                              69

13.3.6.2               Chromatographic integration                                                69

13.3.6.3               GC calibration                                                                            69

13.3.7             Calculations                                                                   70

14                          Shortened forms                                            71

 

 


1                  Introduction

This guideline is applicable to laboratory analysis of contaminated soils for assessment of site contamination and disposal of contaminated soil. It also contains information on the collection of contaminated soil, including storage and handling considerations to enable valid analysis.

 

Rigorous characterisation and quantification of soil contaminants helps to ensure valid assessments of site contamination. Consistency in analysis and assessment can only be achieved if there is uniformity in procedures including sample collection, storage and handling, pre-treatment, extraction, analytical methodology and data analysis. This document gives guidance on quality control, quality assurance and techniques for sample preparation, extraction and analytical methods.

1.1              Audience

This guideline should be used by people undertaking sampling and analysis of potentially contaminated soils. Its main audience includes but is not limited to:

·         laboratory staff

·         environmental consultants, site assessors

·         regulatory licence holders (e.g. for waste management or other statutory processes)

·         custodians of waste/sites containing waste.

1.2              Exclusions

Groundwater analyses are beyond the scope of this Schedule.

1.3              Schedule structure

The Schedule provides guidelines on laboratory analysis of potentially contaminated soils, including:

·         the philosophy behind the methods selected

·         guidance on quality assurance procedures

·         techniques for sample preparation designed to provide confidence and comparability of analytical results.

The Schedule provides analytical methods for potentially contaminated soils and, in particular, a list of methods for analysis of physicochemical properties of inorganic and organic chemicals in soil.

2                  Laboratory analysis of potentially contaminated soil

This Schedule provides guidance on analysis of physicochemical properties of soil, including inorganic and organic analytes commonly found in contaminated soils, and on procedures for sample preparation and for quality assurance.

 

Where possible, the Schedule adopts established ‘standard methods’ from recognised sources such as Standards Australia, the United States Environmental Protection Agency (US EPA), the American Public Health Association (APHA), the American Society for Testing and Materials (ASTM) and the International Standards Organisation (ISO). When analysis is required for contaminants not included in this guideline, analysts should seek comparable established standard methods. Laboratories should ensure any such methods are validated prior to use.

2.1              Scope

Types of soil analyses for assessment of contaminated sites can fall into three broad categories:

·         field measurements that can be performed on-site when collecting samples

·         laboratory-based screening tests to determine type of contamination present

·         quantitative methods specific to known or expected soil contaminants.

This guideline provides detailed guidance for the third category only. The principal objective is to foster greater standardisation of the test methods most likely to be used in the final assessment of a site. General guidance on the first two categories listed above is available in Section 2.5.

 

Whenever possible, accreditation to ISO 17025 should be obtained for all analytical procedures and matrices for the analytes of concern, from the National Association of Testing Authorities (NATA) or one of its mutual recognition agreement partners.

2.2              Determinative methods

This guideline specifies procedures for extraction and digestion of common contaminants. The inclusion of determinative procedures for identification and quantification of contaminant concentrations in sample extracts and digests for every analyte is outside the scope.

 

Descriptions of determinative methods are available for analytes in a range of reference documents including Standards Australia and International standards (US EPA SW-846, APHA 2005, ASTM 2008). In selecting an appropriate method for a particular analyte, the analyst needs to consider the chemical characteristics of the final extract and analyte, and the specificity of the detector.

2.3              Philosophy of methods selected

Soil samples from contaminated sites may be submitted for analysis for various reasons, including to assess:

·         potential risks to human and environmental health

·         legal/financial risks to individuals and organisations.

These circumstances require highly reliable analyses, with analytical data representative of site condition.

 

In addition, large numbers of samples from a site may be required to be analysed within a short time; the sooner results are available, the sooner decisions can be made about the need for site remediation or protection of the public and environment from further contamination.

 

To meet these competing demands for speed and reliability, the extraction/digestion and analytical methods should:

1.      be simple—procedures should be easy to follow and to perform, using equipment and reagents generally available in most environmental laboratories.

2.      be rapid ideally, extraction/digestion and analysis should be sufficiently rapid and non-labour-intensive to enable a large number of samples to be processed within acceptable turnaround times. This should not be at the expense of meaningful analytical results.

3.      be accurate and precise—the test methods listed in these guidelines are regarded as ‘reference’ procedures, mostly derived from authoritative Australian references or internationally recognised authorities such as US EPA or APHA.

4.      They are considered to be sufficiently rigorous and reliable for the assessment of contaminated sites, by virtue of their measured accuracy and precision in validation studies and/or their usage and acceptance as rigorous techniques by the scientific community.

5.      be capable of batch or automated analysis—samples should be able to be processed in large batches without being cumbersome; automated analyses are often preferred.

6.      be capable of simultaneous analysis—procedures should allow a variety of chemical components to be analysed using aliquots of a single extract per sample. This minimises sample processing time and cost and maximises sample throughput.

7.      have an appropriate limit of reporting (LOR)—the selected method should have a limit of reporting, where practicable, no greater than 20% of the relevant soil criteria and validated for a variety of soil matrices, including sand, clay and loams.

8.      be safe—safety should never be compromised, especially when undertaking large batch processing and handling soils from contaminated sites.

 

The analytical methods referenced in this guideline have been selected on the basis of having reliability and where possible, ease of use and efficient data turnaround. The methods primarily measure the potentially mobile or bioavailable fraction of contaminants in soil (not necessarily the total residual contaminant concentrations) because many such residual components (for example, those bound to a silicate matrix) pose little immediate threat to human health or the environment.

2.4              Referenced methods and use of alternative methods

Analysis for regulatory or statutory purposes, or conducted under the principles of this Schedule, should be undertaken by either:

·         the methods specified in this guideline (as updated over time)

or

·         a method verified to be equivalent in outcome to the relevant referenced method.

 

Other extraction and determinative methods may be at least as efficient, accurate and precise (as well as possibly faster and less expensive) than those recommended here, including specially designed commercial systems, for example, digestion units, distillation units and auto analysers. However, it is beyond the scope of this guideline to evaluate all possible alternatives.

 

Where such alternative methods are used, (that is, any methods apart from those specified in this guideline), the user should ensure that the alternative method is at least as rigorous and reliable as the reference method, and either that:

·         it has been validated against an appropriate certified reference material (CRM) on the range of soil types and concentrations most likely to be analysed. This requires adequate recovery of analytes using CRMs during method validation, as well as regular participation in national proficiency trials by bodies such as the National Measurement Institute (NMI) or Proficiency Testing Australia (PTA) or other accredited provider

and/or

·         it has been verified against quantitative data generated by a laboratory that is accredited for the reference method to ISO 17025 by NATA or one of its mutual recognition agreement partners.

The laboratory should document the method performance verification and make the data available for independent audit.

 

See Section 3.2 for more guidance on method validation.

2.5              Screening tests

Some screening tests in common usage—including laboratory screening tests and field tests, (for example, field chemical test kits and field analysers)—may be fast and cheap but, by their nature, are less rigorous and reliable than the analytical methods described here. They may be suitable for less exact tasks such as preliminary assessments, mapping contaminant distribution at known contaminated sites or monitoring the progress of site clean-up or remediation programs (refer Schedule B2, Section 7.4).

 

Data from screening tests is not suitable for detailed assessment of contaminated sites or for validating clean-up. These tasks require a high degree of accuracy and reliability and data should be based upon results from one of the validated analytical tests referenced here, or other methods that have been shown to be at least as rigorous and reliable for the soil matrix in question.

 

The accuracy and precision of any analysis should be sufficient for the intended purpose. Therefore screening methods should be evaluated for appropriate analyte specificity, repeatability and reproducibility prior to use.

2.6              Confirmation of organic compounds (for non-specific techniques)

Where non-specific analytical techniques are used, (e.g. gas chromatography (GC) or high performance liquid chromatography (HPLC)), the identity of organic compounds should be confirmed by one of the methods detailed in the NATA Field Application Document ISO/IEC 17025 (NATA 2011). These include mass spectrometric detection, variation of the test procedure (e.g. different column stationary phase), another test procedure (e.g. alternative detector) or conversion of the analyte to another compound (e.g. derivation technique).

 

A mass spectral library match alone is only sufficient for tentative identification. Confirmation is achieved (i.e. no additional confirmatory analysis is required) if GC/MS or HPLC/MS methods are employed and standards of the compound are analysed under identical conditions (US EPA SW-846, Method 8000B). A compound identity is then confirmed if all of the following criteria (US EPA SW-846: Method 8260B, Method 8270D) are met:

·         the intensities of the characteristic ions of the compound in the sample should maximise in the same scan, or within one scan, as that of the reference calibration check standard

·         the relative retention time (RRT) of the sample component is within ±0.06 of the RRT of the reference calibration check standard

·         the relative intensities of the characteristic ions (see note immediately below) in the sample check standard.

Note: The characteristic ions are generally defined as the three ions of greatest intensity in the preceding calibration check standard.

2.7              Leachability and bioavailability

Some methods for assessing mobility and availability of soil constituents are based on methods designed for agronomic studies and land surveys (e.g. metal availability, as part of soil nutrient assessment) and hence are only applicable to soils expected to have relatively low contaminant concentrations (e.g. background samples or natural soil).

 

Such methods should be used with caution on contaminated soils, as the high concentrations of analytes in contaminated soil may exhaust the exchangeable capacity of the reagents and lead to false results. These tests have not yet been shown to apply to contaminated soils, and meaningful results can only be obtained from natural soils or background samples.

 

This Schedule describes two leachability methods for assessing the mobility of common metal contaminants in contaminated site assessments. Other methods available to study mobility of metal ions and nutrients for agronomic reasons are highly specific to the soil type, chemical species, and biota (usually plants) being studied, and are not recommended for generic studies of contaminated soils.

 

See Section 12 for more discussion of methods to assess leachability of soil contaminants.

2.8              Use of laboratory results

Effective site assessment is dependent on a partnership between the site assessor and the laboratory, to ensure that:

·         samples are collected, transported and received by the laboratory in a condition suitable for analysis

·         the laboratory understands the information required by the site assessor

·         the analyst communicates all relevant information to the site assessor in a timely manner

·         the assessor appreciates the uncertainties and limitations associated with the analytical data.

When using the results of laboratory analysis, the site assessor should be aware of the relationship between the property measured by the method (e.g. total or leachable concentrations), the measurement uncertainty and the basis for the derivation of any investigation level or response level with which it is compared.

3                  Quality assurance and quality control

3.1              Definitions

The terms ‘quality assurance’ and ‘quality control’ are often misinterpreted. This guideline defines them as follows (ISO 8402–1994):

 

‘Quality assurance (QA) is all the planned and systematic activities implemented within the quality system and demonstrated as needed to provide adequate confidence that an entity will fulfil requirements for quality.’

 

This encompasses all actions, procedures, checks and decisions undertaken to ensure the accuracy and reliability of analysis results. It includes the application of routine documented procedures to ensure proper sample control, data transfer, instrument calibration, the decisions required to select and properly train all staff, select and maintain equipment, select analytical methods, and the regular scrutiny of all laboratory systems and corrective actions applied forthwith.

 

Quality control (QC) is ’the operational techniques and activities that are used to fulfil the requirements for quality’.

 

These are the QA components that serve to monitor and measure the effectiveness of other QA procedures by comparing them with previously decided objectives. They include measurement of reagent quality, apparatus cleanliness, accuracy and precision of methods and instrumentation, and reliability of all of these factors as implemented in a given laboratory from day to day.

 

A complete discussion of either of these terms or the steps for implementing them is beyond the scope of this guideline; suffice to say, sound laboratory QA systems and QC procedures are essential. In brief, laboratories should incorporate quality laboratory management systems and participate in accreditation and/or self-audit systems, to ensure reliable results are produced by trained analysts, using validated methods and suitably calibrated equipment, and to maintain proper sample management and recordkeeping systems.

 

For more information on good laboratory practice and QA procedures, refer to guidance from NATA (Cook 2002) and Standards Australia (AS 2830.1-1985).

3.2              Method validation

This is the process of obtaining data on a method in order to determine its characteristic performance and to establish confidence in the use of that method to provide reliable results. Method validation needs to be performed by each laboratory before that method is adopted and applied to the analysis of actual samples.

 

It is difficult to obtain complete validation data for all analytes covered in these guidelines due to large variations in soil types and physicochemical properties, and lack of suitable or reliable reference standard materials. For some analytes (e.g. soil pH), conventional validation data has no bearing on method performance between one soil sample and the next; for such analyses, better performance indicators may be obtained through inter-laboratory comparisons.

 

This guideline recommends certain extraction procedures or, in some cases, complete methods—each laboratory should fully validate each method used (from extraction through to the determinative step) following the principles for quality assurance and method validation described in this Section and other relevant references (US EPA SW-846, APHA 2005-1040B method validation, NATA Technical Note 23, NATA Technical Note 17).

 

Validation should be performed on the range of soil types most likely to be analysed, or on the most complex soil type likely to be analysed (e.g. clay instead of sand).

All validation steps pertaining to the method should be recorded and retained while the method is being used.

 

Method performance should be based on extraction of a CRM and/or spiked samples (NATA Technical note 17) or compared with a more rigorous method.

 

The minimum validation data required are:

·         Accuracy Precision

·         Limit of detection (LOD)and limit of reporting (LOR)

·         Linearity (range over which accurate quantification is expected)

·         Uncertainty of measurement (MU).

3.2.1        Accuracy

Accuracy is a measure of the closeness of the analytical result to the 'true' value (NATA Technical note 17). When low analyte concentrations are present the results of a reference method may differ by as much as ±30 % of:

·         the expected value of a certified reference material (CRM) of similar matrix; or

·         the value obtained by another currently-accepted and separately validated quantitative method for the sample matrix.

This is a particular issue when analyte concentrations are less than 10 times the minimum detectable concentration. Apparent lower recoveries than those specified for the method will occasionally be obtained for CRMs which have been assessed by more rigorous methods involving matrix dissolution. The specific analyte cited in the CRM certificate should match that being determined under this Schedule. For example, if the certified reference values are obtained using aqua regia digest, only the aqua regia method should be applied for comparison with this CRM. Otherwise, an alternative CRM should be used.

3.2.1.1       Percent recovery

This is the most realistic and useful component of the daily quality control performance (APHA 2005), and describes the capability of the method to recover a known amount of analyte added to a sample (in the form of either a laboratory control sample (LCS), matrix spike or surrogate compound spike).

 

The sample is spiked with a known quantity of the analyte, such that the total of the suspected natural concentration of the analyte plus the spike is within the working range of the method. For compliance monitoring, the spike level should be at or near the regulatory limit, or in the range of 1-5 times the background concentration.

 

If the background concentration is not known, the spike level may be at the equivalent concentration to the midpoint of the calibration range, or approximately 10 times the LOR in the matrix of interest (US EPA SW-846, Method 3500C).

 

The longer the spiked analyte can remain in the sample before extraction or digestion, the closer is the simulation to recovering the analyte from the natural sample (except for volatile organics).

 

Percent recovery is calculated as follows:

Per cent recovery         = c – a x 100

                                          b

where:             

a = measured concentration of the unspiked sample aliquot

b = nominal (theoretical) concentration increase that results from spiking the sample

c = measured concentration of the spiked sample aliquot

 

Note: If ‘a‘ is known beforehand, then ‘b‘ should be approximately equal to ‘a‘, and ‘c‘ should be approximately twice that of ‘a‘, for 100% recovery.

 

In general, at least 70% recovery should be achievable from a reference method; some standard methods state that recoveries for validated methods can be lower.

 

’Recovery of the analyte need not be 100%, but the extent of the recovery of the analyte and internal standard should be consistent, precise, and reproducible’ (FDA 2001).

 

Further information may be obtained from General requirements for the competence of testing and calibration laboratories (ISO 17025, 2005) and Uncertainty of measurement—Part 3: Guide to the expression of uncertainty in measurement (ISO/IEC Guide 98-3:2008).

3.2.2        Precision

Precision is a measure of the variation in the method results. It is a combination of two components, repeatability and reproducibility, and is expressed in terms of standard deviation (SD) or relative standard deviation (RSD) of replicate results (APHA 2005).

3.2.2.1       Repeatability

This is a measure of the variation in the method results produced by the same analyst in the same laboratory using the same equipment under similar conditions and within a short time interval (Eaton et al. 2005).

3.2.2.2       Reproducibility

This is a measure of the variation in the method results for the same sample(s) produced by different analysts in different laboratories under different conditions and using different equipment. It measures the 'ruggedness' of the method. Reproducibility data should be obtained as part of the method validation procedure, and are best obtained through inter-laboratory comparisons and proficiency studies.

3.2.2.3       Confidence limit  and confidence interval

When results are qualified with standard deviations (SD) or their multiples (for example, ‘x ± SD‘), these are taken to be their confidence limits. This means that a result of 10±4 mg/kg would have confidence limits (CLs) of 6 and 14 mg/kg and a confidence interval (CI) from 6 to 14 mg/kg (APHA 2005). In a normal distribution, 95% of results are found within approximately twice the standard deviation of the mean (e.g. ‘95% CI = x ± 2SD‘). Further clarification of these terms may be found in standard statistics texts.

3.2.3        Limits of detection and reporting

3.2.3.1       Method detection limit

The method detection limit (MDL) is the concentration of analyte which, when the sample is processed through the complete method, produces a response with a 99% probability that it is different from the blank (NATA Technical Note 17). It is derived by:

·         analysing at least 7 replicates of a sample with a concentration close to the estimated MDL, and determining the standard deviation

·         calculating the MDL as follows

MDL = t * Std Deviation, using a one-sided t distribution where, for 7 replicates, t= 3.14 for 99% confidence levels.

3.2.3.2       Limit of Reporting

The limit of reporting (LOR) is the practical quantification limit (PQL), and is the lowest concentration of an analyte that can be determined with acceptable precision (repeatability) and accuracy under the stated conditions of a test (NATA Technical Note 17). It is calculated as follows (APHA 2005):

 

LOR = PQL = 5 x MDL

 

The LOR should be at or below the relevant HIL, HSL or EIL and should be equal to the lowest calibration standard (as expressed in units of mg/kg of soil sample).

3.3              Laboratory Batch QC procedures

The laboratory should adopt, at a minimum, the QC concepts and procedures described below and be able to demonstrate:

·         method proficiency within the laboratory

·         conformance to the performance characteristics expected of the method

·         confidence in the results produced.

Recommended QC procedures for all soil analyses are described in US EPA SW-846 Chapter 1: ‘Quality Control‘.

3.3.1        Process batch and QC interval

For the purposes of QC requirements and QC monitoring intervals, a laboratory process batch is deemed to consist of up to 20 samples that are similar in terms of matrix and test procedure, and are processed as one unit for QC purposes. If more than 20 samples are being processed, they are considered as more than one batch.

3.3.2        Method blank

This refers to the component of the analytical signal that is not derived from the sample but from reagents, glassware, analytical instruments, etc. It can be determined by processing solvents and reagents in exactly the same manner as for samples. When laboratories report method blanks, the uncorrected result and the method blank should be reported in the same units of measurement.

 

There should be at least one method blank per process batch.

 

Method blank data is reported with the primary sample data, thus enabling the site assessor to assess potential method bias for the relevant analytes.

3.3.3        Laboratory duplicate analysis

This is the analysis of a duplicate sample from the same process batch. If possible, the sample selected for duplicate analysis should have an easily measurable analyte concentration. The variation between duplicate analyses should be recorded for each process batch, to provide an estimate of the method precision and sample heterogeneity.

 

Samples reasonably perceived to contain target analytes should be chosen for the duplicate analyses, though samples with obviously high concentrations of interferents—which will likely require subsequent dilution of sample extracts and raised LORs—should not be used for duplicate analysis. There should be at least one duplicate per process batch, or two duplicates if the process batch exceeds 10 samples.

 

If results show greater than 30% difference, the analyst should review the appropriateness of the method being used.

 

Duplicate analysis data is reported with the primary sample data, thus enabling the site assessor to assess method precision for the relevant analytes.

3.3.4        Laboratory control sample 

A laboratory control sample (LCS) comprises a standard reference material, or a matrix of proven known concentration or a control matrix spiked with all analytes representative of the analyte class. Representative samples of either material should be spiked at concentrations equivalent to the midpoint of the preceding linear calibration or continuing calibration check, upon which sample quantification will be based. Thus the concentrations should be easily quantified and be within the range of concentrations expected for real samples.

 

The LCS should be from an independent source to the calibration standard, unless an ICV (independent calibration verification) is used to confirm the validity of the primary calibration.

 

There should be at least one LCS per process batch.

 

LCS percent recovery data is reported with the primary sample data, thus enabling the site assessor to assess method accuracy for all targeted analytes, as distinct from method accuracy for site-specific soil samples (see Section 3.3.5 Matrix spikes below). The laboratory should use statistically derived quality control limits from ongoing LCS percent recovery data, for all target analytes, and report such QC limits with the sample data.

3.3.5        Matrix spikes

A matrix is the component or substrate (e.g. water, soil) that contains the analyte of interest. A matrix spike is an aliquot of sample spiked with a known concentration of target analyte. A matrix spike documents the effect (bias) of matrix on method performance.

 

Matrix spikes should be added to the analysis portion before extraction or digestion and, in most cases, added at a concentration as close as practicable to the corresponding regulatory level (e.g. the relevant HIL or EIL). If the analyte concentration is less than half the regulatory level, the spike concentration may be as low as half the analyte concentration but not less than the LOR.

 

To avoid differences in matrix effects between sample and spiked sample, the matrix spikes should be added to the same nominal mass of soil sample as that which was analysed for the unspiked sample.

 

There should be one matrix spike per soil type per process batch.

 

If the percent recovery of the matrix spike is below the expected analytical method performance, the laboratory should investigate the likely cause and, where a suitable amount of soil mass remains, re-extract and analyse another spiked soil. It may be necessary to use other internal calibration methods (for example, isotope dilution, a modification of the analytical method or alternative analytical methods) to accurately measure the analyte concentration in the extract.

 

If, after investigation, the matrix spike percent recovery is still below method QC limits then this failed recovery should be reported to the client with an explanation to show the limitations of the method for that particular matrix. An acceptable LCS result may indicate that it is the matrix, not the method, that may be the issue but it is not acceptable to assign poor recovery to matrix effects, without a reasonable investigation.

3.3.6        Surrogate spikes (where appropriate)

Surrogate spikes are known additions to each sample, blank, matrix spike or reference sample, of compounds that are similar to the analytes of interest in terms of:

·         extraction efficiency

·         recovery through clean-up procedures

·         response to chromatography or other determination

·         instrumental detector response

but which:

·         are not expected to be found in real samples

·         will not interfere with quantification of any analyte of interest

·         may be separately and independently quantified by virtue of, e.g. chromatographic separation or production of different mass ions in a GC/MS system.

Surrogates provide a means of checking that no gross errors have occurred at any stage of the procedure and which may cause significant analyte losses.

 

Surrogate spikes are only appropriate for organic analyses, for example, chromatographic methods. Where they are used, they should be added to all samples being analysed and are added to the analysis portion before extraction. Surrogate spike compounds may be deuterated, alkylated or halogenated analogues, or structural isomers of analyte compounds. Surrogate compounds used in analytical methods, normally three per method, should be chosen to monitor the variable method performance of the entire target analyte list.

3.3.7        Internal standards (where appropriate)

Use of internal standards is highly recommended for chromatographic analysis of organics and some inorganic analyses, to check the consistency of the analytical step (e.g. injection volumes, detector response and retention times for chromatographic systems). Internal standards provide a reference against which quantitative data may be corrected for sample-specific variation in instrumental response (for organics analysis only).

 

For organics analysis, internal standards are normally synthetic deuterated compounds (isotopic analogues) of target compounds. Internal standards are added to each final extract solution after all extraction, clean-up and concentration steps. The addition is a constant amount of one or more compounds with qualities like those listed for surrogates, i.e. a similar instrumental response to that of the target compounds, etc.

 

Adjustments for variations in injection volume and instrument sensitivity are made by quantifying against the ratio of:

 

(peak height or area for analyte) : (peak height or area for the referenced internal standard) X (a response factor determined from a preceding calibration standard)

 

Methods should define specific QC criteria for internal standard response and procedures for analyte quantification where response is observed outside of predefined limits.

3.4              Documentation of validation and QC procedures

All method validation steps (including raw data and data validation assessment) should be recorded and retained while the method is in use. Results of validation procedures should be retained to enable monitoring of method reliability, confidence intervals for analysis results and trends in precision and accuracy over time, or with variation of equipment, source of calibration or analyst.

 

After completion of analysis of each sample process batch, all documentation relating to the samples and their analysis (including raw data and supporting QC data) should be retained for at least three years (NATA 2011, Section 4.13) so that all relevant information may be easily retrieved. This helps establish chain-of-custody of the sample and traceability of all data, and enables reviewing the analysis during an audit or investigation of a questionable result.

 

This data retention requirement applies to both hard copy data and data in electronic formats. Laboratories should ensure adequate electronic data storage and backup to ensure data and documentation relating to analyses can be retained.

3.5              Field duplicate and secondary duplicate (split) samples

These field QC processes are implemented by the site assessor rather than the laboratory though laboratories and sample collectors should both be aware of the requirement and purpose.

3.5.1        Field duplicate

Field Duplicate: a blind field replicate sample submitted to the laboratory to provide a check of the precision (repeatability) of the laboratory‘s analysis.

 

At least 5% of samples (i.e. 1 in 20 samples) should include a larger than normal quantity of soil collected from the same sampling point, removed from the ground in a single action if possible, and mixed as thoroughly as practicable and divided into two vessels. These samples should be submitted to the laboratory as two individual samples and coded separately to avoid identification of their common source.

 

A similar test of analysis repeatability is provided by re-submission of previously analysed samples, provided the stability of analyte is adequate under the storage conditions used between the two submission dates.

 

Data for primary and duplicate is collated and reported as a relative percent difference (RPD) of the mean concentration of both samples. If results show greater than 30% difference, a review should be conducted of the cause (e.g. instrument calibration, extraction efficiency, appropriateness of the method used, etc.).

3.5.2        Secondary duplicate

Secondary Duplicate: a blind field replicate sample submitted to a secondary laboratory (inter-laboratory check sample) to provide a check of the analytical performance of the primary laboratory and specifically, the reproducibility of primary laboratory data.

 

At least 5% of samples from a site should be homogenised and split, with one duplicate sample set submitted to a secondary laboratory (independently accredited for ISO 17025, by NATA or one of its mutual recognition agreement partners) and the remaining samples submitted to the primary laboratory. The duplicate sample should be submitted independently and coded to avoid identity as a duplicate sample. The client should stipulate that each laboratory analyses the split samples for the same analytes using, as far as possible, the same methods recommended in these guidelines.

 

For comparability of data, there should be minimal delay in sample submission to each laboratory to allow minimum time difference between analyses, especially for analysis of volatile analytes. It is best practice to submit the secondary duplicate (‘check sample‘) directly to the secondary laboratory to minimise time in transit.

 

Data for primary and duplicate is collated as a relative percent difference (RPD) of the mean concentration determined by both laboratories. Higher variations can be expected for organic analyses compared to inorganic analyses, and for samples with low analyte concentrations or non-homogeneous samples.

 

If results show greater than 30% difference, a review should be conducted of both laboratories and of the appropriateness of the methods being used.

3.5.3        Replicates for volatile organic compound analysis

For analysis of volatile organic compounds (VOCs), field duplicate and secondary duplicate samples should be created as rapidly as possible by halving the sample and placing each half in a smaller container, compacting and topping up to achieve zero headspace in each, attempting to minimise volatile losses. They should be submitted as soon as possible to the laboratory/ies to prevent loss while in storage or transit.

4                  Sample control, preparation and storage

The laboratory should maintain rigorous procedures and documentation for sample control, from the time the sample is received. This includes the entire process from registration of the sample through to pre-treatment and sample analysis, sample storage and disposal. Unique identification of each and all portions of every sample is mandatory. Sample integrity should be maintained as far as possible, even after completion of analysis; samples should be stored in controlled refrigeration for at least two weeks after issue of analytical data, to enable repeat analysis in case any anomalous results are observed by the laboratory or the site assessor, subsequent to reporting analytical data.

4.1              Sample preparation – general principles

To obtain reproducible results it is essential that laboratories use standardised procedures when preparing samples. These procedures will not necessarily be the same for each sample but will comprise various combinations of the following treatments:

·         separation and removal of extraneous components

·         homogenising

·         drying

·         hand grinding

·         sieving

·         partitioning (to obtain representative portions).

The combination of treatments applied to any sample will depend primarily on the nature of the analytes of interest. These can be split into three broad categories:

1.      non-volatile compounds (including most metals, inorganics and some heavy organics)

2.      semi-volatile compounds (many organics, some metals and other inorganics subject to evaporative losses)

3.      volatile compounds (such as organic solvents and inorganic gases).

The following sections discuss the individual steps in sample preparation for these three categories.

 

Throughout the sample preparation step, the analyst should be aware of the potential for any bias to be introduced, and report any bias noted in the results.

 

WARNING: Handling potentially contaminated soil and fine dust may present a health hazard. All preparations described in this section should be performed in accordance with work health and safety requirements.

 

Asbestos or acid sulfate soils: This Section does not apply to the sampling and handling of soil containing asbestos or acid sulfate materials. For guidance consult Analysis of acid sulfate soil—dried samples—methods of test (AS 4969.0-14-2008/2009) and the Method for the qualitative identification of asbestos in bulk samples (AS 4964-2004).

4.2              Sample preparation: non-volatiles and semi-volatiles

4.2.1        Separation and removal of extraneous (non-soil) components

Prior to processing the sample (e.g. drying, grinding or mixing), remove any vegetation and other non-soil material (including rocks, gravel, concrete, particles naturally greater than 5 mm) by hand or by sieving, except for samples to be analysed for volatile components, since this process may lead to significant analyte losses. The analyst should confirm with the site assessor or client whether any fraction of the removed material is to be analysed.

 

Also take a separate weighed portion of the sample to determine moisture content (see Analytical Methods, Section 5 in this Schedule). Report moisture content with the analytical result so that analyte concentrations may be estimated on a ‘dry-weight’ basis.

 

As stated previously, the analytes of concern should be the ‘available‘ contaminants, which generally reside on the surface of the soil particles. It is likely that larger particles and rocks will contain, on a weight basis, considerably less contaminant than the smaller particles. In certain circumstances, however, it will be prudent to also analyse the larger particles, preferably separately. The reverse will be likely if contamination of a site has arisen by importation of contaminated screenings or other large particles.

 

Any material removed for analysis should be weighed and its proportion relative to the entire sample, and its description, recorded. If required, this mass and the description may be included in the analytical report. The significance of the analyte concentration in the soil or fraction of removed material can then be assessed relative to the entire sample composition.

 

The removed material (including the materials retained on the sieve) should be labelled and retained for possible future analysis.

4.2.2        Homogenising (for non-volatile constituents)

 

Note: This section only applies to non-volatile samples; samples of volatile contaminants should not be homogenised by stirring, grinding or sieving. Procedures for volatile analytes are described in Section 4.3 below.

 

Most analytical methods require analysis of only a portion of the sample, sufficient to provide a quantifiable response. The amount of sample received by the laboratory is usually larger than required for a single determination and any additional analyses for QA purposes.

 

Depending on the analyses required (excluding volatile analysis), a homogeneous test sample is prepared from either the field-moist (i.e. ‘as received‘) or dried sample. The analysis portions are then taken from this test sample.

 

The sub-sample taken should comprise at least 25% by weight or 200 g of the sample received by the laboratory (laboratory sample), whichever is the smaller, or some other sub-sample that can provide a well-mixed portion representative of the whole sample. It should be thoroughly disaggregated and mixed using a mortar and pestle, or other appropriate method. If no test requiring the original untreated sample will be needed in future, the entire sample may be homogenised; however, it is advisable to keep a portion in the ‘as received‘ state to check, if necessary, that no contamination has occurred during the homogenising process. Described below are the pre-treatment procedures to obtain homogenised field-moist and dry analysis portions.

4.2.3        Preparation of field-moist (‘as received’) analysis portions

In general, soils to be tested for organic analytes, especially rapidly degradable or otherwise labile contaminants, should not be dried but should be analysed in a field-moist state. If an excess of moisture would affect the extraction efficiency, the sample may be ‘dried' by mixing the analysis portion with anhydrous sodium sulfate or magnesium sulfate prior to extraction (US EPA SW-846, Method 3540C).

 

Field-moist samples will often not be amenable to mechanical grinding or sieving. For those samples that are suitable, the process involves taking at least 25% by weight or 200 g of the laboratory sample, whichever is the smaller (or other sub-sample that can provide a well-mixed portion representative of the whole sample), and thoroughly grinding and mixing by hand in a mortar and pestle, or using other appropriate techniques, to obtain a homogeneous sub-sample. Equipment should be thoroughly cleaned between samples, or other systems put in place to ensure no cross-contamination.

 

For most metals and inorganics, better analytical reproducibility is obtained using air-dried soil (see Section 4.2.4 below). However, if the sample is to be analysed for these analytes in the field-moist state and if it is amenable to sieving (for example, sandy loam), it should be passed through a 2 mm plastic sieve to remove large soil particles and other extraneous particles—ensure that the sample contains no solid particles distinctly different from the soil, such as fragments of metal or other unusual particles.

 

Note: Do not grind samples being analysed for metal contaminants, as this can release natural metals from the interior of soil grains that are not normally available.

Store the treated sample in a suitable container.

 

Clean all equipment to minimise sample cross-contamination; this can be confirmed by analysing equipment rinsates and/or control samples.

4.2.4        Preparation of dry analysis portions (non-volatiles only)

Air-drying helps to give a representative analysis portion by producing samples amenable to grinding, sieving and splitting. However, air-drying may modify the chemical form of some species and hence affect the results obtained (Adam & Anderson 1983, Bartlett & James 1980, Harry & Alston 1981, Khan & Soltanpour 1978, Leggett & Argyle 1985, Specklin & Baliteau 1989).

 

The effect of air-drying temperature on analyte modification is not completely understood but in some cases it seems to change the bioavailability or extractability of the analyte. The impact of air-drying on analysis may be more pronounced in certain soil types and in sediments. Therefore, air-drying is only applicable to some methods of soil analysis.

 

Soils for most metals and some other inorganic analytes can be air-dried, and then sieved. However, the procedure described below is not applicable to analysis of volatile constituents—including volatile metallics such as metallic mercury, methyl mercury or tetraethyl lead—or where analytical methods specifically forbid such preparation (e.g. certain leaching tests). Samples for volatile metallics should be homogenised and sub-sampled in the field-moist state.

 

Note: Grinding samples will increase surface area and may give higher results.

4.2.4.1       Sample drying

Dry at least 25% by weight or 200 g of the sample, whichever is the smaller, by spreading the soil on a shallow tray of a suitable non-contaminating material, such as plastic or stainless steel. If necessary, break up large clods with a spatula to speed up the drying process. Allow the soils to dry in the air (at <40°C), ideally with the trays placed in a clean air chamber, or a non-contaminating oven at 40 ± 3°C. The relative humidity should be less than 70% to achieve drying within a reasonable time. The sample is dry when the loss in mass of the soil is not greater than 5% per 24 hours (AS 4479.1-1997).

 

4.2.4.2       Grinding of dry sample

Note: Grinding increases the surface area and can give higher results.

 

Grinding is not recommended for analysing ‘available‘ metal contaminants, as it can release natural metals inside the soil particles that are not normally available.

 

Where necessary, crush the dry sample in a mortar and pestle of appropriate material (glass, agate or porcelain) or other suitable grinding apparatus to achieve a particle size appropriate to the analysis. Mix the sample as thoroughly as possible.

 

Take care to avoid contamination during the grinding process, and clean equipment between each sample to prevent cross-contamination. See below. To evaluate decontamination efficiency, the final wash solution should be sampled and analysed (Barth & Mason 1984); one final wash sample per process batch or 1 in every 10 samples ground, whichever is the smaller. Alternatively, treat a well-characterised control soil sample similarly. If there is significant carry-over due to the grinding process, the results from that process batch may have to be rejected.

 

WARNING: Grinding of soils can produce fine dust particles that may present a health hazard if inhaled. Sample grinding, and subsequent handling, should be performed in accordance with work health and safety requirements.

4.2.4.3       Sieving

Unless impracticable or not recommended for a specific method, the sample portion for analysis should be of a size to pass a 2.0 mm aperture sieve. This may be achieved by grinding, if appropriate.

 

If small analysis portions (<10 g) are required, or smaller sieve sizes, grind at least 10 g of the <2 mm fraction to pass through smaller mesh sieves (0.15, 0.5 or 1.0 mm sieve size for sample sizes of <1 g, <2 g and 2-9 g respectively).

 

If another particle size is chosen, this should be consistently used within an analysis regime and reported with analytical results.

4.2.4.4       Partitioning of dry samples to obtain representative analysis portions

The analysis portion of the dry sample should be a representative sample. For sufficiently dry samples, use of a chute splitter (riffler) is recommended, or the entire sample should be thoroughly mixed and divided using the ‘cone-and-quarter’ technique or by any other suitable sampling apparatus. This equipment should be made of appropriate material (e.g. stainless steel) to avoid contamination.

 

Cone and quarter technique:

a. Spread soil into thin even layer

b. Divide into four quadrants

c. Combine and mix soil from two opposite quadrants.

 

Repeat steps a. to c. until required quantity of soil is obtained for analysis (including any replicate analyses and extra portions required for quality assurance purposes).

 

If using mechanical sample divider, use in accord with the manufacturer’s instructions.

Store the remaining homogenised dry sample separately in a glass screw-cap jar or other appropriate vessel.

 

Note: Mechanical grinding of dry soil, for example, in a ring mill, will mix the sample but use of the cone-and-quarter technique or a mechanical sample divider is preferred, to avoid sub-sampling only the larger particles.

4.2.4.5       Equipment cleaning during sample preparation (including grinding, sieving and homogenising procedures)

Cleaning procedures will vary according to the analyte/s being determined. Minimum procedures include detergent washing followed by rinsing with deionised water and then oven drying. For trace metal analysis, it may be necessary to incorporate soaking in dilute acid followed by deionised water rinsing. For analysis of organics, equipment will normally need solvent rinsing followed by air drying, prior to homogenising samples.

For quality control, the final wash solution should be sampled and analysed to evaluate the decontamination efficiency (Barth & Mason 1984); one final wash sample per process batch or 1 in every 10 samples ground/sieved/processed, whichever is the smaller. Alternatively, treat a well-characterised control soil sample similarly. If there is significant carry-over due to the grinding/sieving process, the results from that process batch may have to be rejected.

4.2.5        Sample Preparation Summary - Non-volatiles and semi-volatiles

Note: Analysis of volatile contaminants such as C6-C10 fractions should be undertaken prior to any other analysis required from that sample. Sampling and sub-sampling for volatiles should be undertaken as described in Section 4.3 below.

 

All samples (non-volatile and semi-volatile)

1.      Remove vegetation and large stones and other particles (>5 mm) unless they are to be included for bulk analysis. Record proportion by weight with a description of each fraction of material removed.

2.      Select at least 25% by weight or 200 g of the laboratory sample, whichever is the smaller, including sufficient amounts for repeat analyses or other analysis on this same sample including moisture content (using field-moist sample).

Field-moist sample analysis

e.g. semi-volatiles, analytes for which drying may lead to losses  (Details in S.4.2.3)

Dried sample analysis

non-volatiles (Details in S.4.2.4)

3. (Intentionally left blank)

3. Dry in oven or air chamber (40±3°C)

Sample is dry when the loss in soil mass is not greater than 5% per 24 hours.

4. Grind in clean mortar and pestle to disaggregate soil particles and to produce a homogeneous test sample.

- Where suitable (e.g. for non-volatiles)

4. Where appropriate (usually organics, not metals), grind to disaggregate the soil particles, using a clean mortar and pestle or using other appropriate techniques, to obtain a homogeneous sub-sample.

5. For ‘field-moist‘metal samples or other inorganics or non-volatiles that are amenable to sieving (e.g. sandy loam), pass through a 2 mm plastic sieve.

Ensure no extraneous particles in sample, otherwise analyse in air dried state.

5. Pass through a mesh sieve (2 mm).

6. Dry a separate sub-sample to determine moisture content (see method in Section 6). Report moisture content with analytical result so that analyte concentrations may be estimated on a ‘dry-weight’ basis.

6. Weigh the particles >2 mm diameter and set aside for later analysis if required (and to examine for large particles of solid contaminant if necessary).

 

7. Partition the (<2 mm diameter) fraction with sample divider (e.g. riffler) or ‘cone & quarter‘ or alternate comparable method. Ensure sufficient soil is obtained to cover all analyses, including repeats and QA. (See S 4.2.4.4)

 

8. If small analysis portions (<10 g) are required, or smaller sieve sizes, grind at least 10 g of the <2 mm fraction to pass through smaller mesh sieves (0.15, 0.5 or 1.0 mm sieve size for sample sizes of <1 g, <2 g and 2-9 g respectively).

4.3              Volatile analytes - sample collection and preparation

These guidelines generally do not include instructions for sample collection, with the exception of samples collected for volatile analytes, as the sampling method has a direct bearing on the analysis method and reliability of the results. The site assessor may request the laboratory to advise on relevant collection techniques or to supply appropriate equipment.

 

For samples requiring analysis of volatiles as well as non-volatiles and/or semi-volatiles, it is recommended that additional, separate samples are taken for the various types of analysis, to allow for volatile analysis to be completed and repeated if necessary on samples which have not been homogenised or otherwise inappropriately treated.

4.3.1        Sample collection

Samples should be collected with minimal sample disturbance and handling to avoid evaporative losses, as detailed in AS 4482.2-1999. Ideally, sampling is carried out using a coring device; however if this is not available, an alternative device such as a trowel may be used. In all cases, the sample-taker should ensure that the sample remains intact and the container is filled as full as possible to ensure minimal headspace and void space and evaporation potential. In many cases, taking duplicate samples is recommended to allow sample re-analysis if required (e.g. if contaminant levels are over range).

 

Since volatiles are easily lost from the ground‘s surface, sampling soil for volatile analysis should not be carried out from the surface layer unless a very recent chemical spill is being investigated.

 

Where the sample container will be subsequently opened to obtain a sub-sample for analysis, the dimensions of the original sample core taken should be such as to leave a minimum of void space (headspace, and between core and container walls) in the vessel. Where the whole sample is to be purged or extracted without prior opening, this need not apply.

 

If soils are granular and easily sampled, place sample cores immediately into:

·         two or more pre-weighed 40 mL glass volatile organic analysis (VOA) vials with PTFE-lined pierceable silicone septum caps

or

·         one or more wide-mouth glass jars (usually 125 mL or 250 mL) with PTFE-lined lid (see Table 4-1, Chapter 4 in SW-846 revision 4, 2007), and sub-sample according to the procedures given below.

If soils are difficult to sample, (for example, highly compacted or hard clays), it is recommended that a minimum of three core samples be placed into pre-weighed 40 mL glass VOA vials marked at a level corresponding to the required sample weight for analysis. One sample may be used for preliminary screening analysis if desired, the others for analysis by purge and trap.

 

Once samples are taken, ensure that jar or vial closures are free of soil particles before capping. Samples should be sealed and transported to the laboratory as soon as practicable, under suitable cooling aids (preferably ice bricks or in a refrigerated container) to ensure samples start cooling as soon as possible, and they should be stored in a refrigerator (≤6°C) until analysis.

 

Note 1: The 40 mL VOA vials are particularly effective in conjunction with modified closures (US EPA SW-846, Method 5035), or suitably designed purge and trap instruments, which allow the vial to function as a sparge vessel for purge and trap analysis. This means there may be no need to open the vial to prepare an analysis sample.

 

Note 2: Using larger containers may be more convenient and possibly result in fewer analyte losses where removal of test sub-samples is required (Ilias & Jaeger 1993).

 

Note 3: While immersion of samples into methanol on-site is effective in preserving volatile organics (Lewis et al. 1991), such a practice may not be practicable or permissible according to local laws. Handling volatile chemicals in the field, and transporting them, can have work health and safety implications and is not generally recommended unless so advised by the analyst to meet a specific requirement.

4.3.2        Preliminary screening analysis

Laboratories may perform a preliminary screen analysis of soils to prevent contamination of purge and trap equipment by samples with a high contaminant load. This is done by:

·         methanol extraction of a core sample in a 40 mL VOA vial. (Methanol is added with a syringe through the septum cap. A portion of the methanol extract is analysed by purge and trap or other method.)

or

·         headspace analysis (US EPA SW-846, Method 5021)

or

·         hexadecane extraction (US EPA SW-846, Method 3820)

or

·         rapidly removing a core sample from a chilled 125 mL/250 mL jar sample and transferring to a vial for analysis as in methanol extraction or headspace analysis above.

After sub-sampling, immediately reseal jar and return to refrigerator storage (≤6ºC).

 

If analysing whole 40 mL vial samples, note pre-sample weight beforehand and subtract vial weight to determine sample mass.

 

If screening results indicate a low analyte level suitable for purge and trap analysis, perform this using a second 40 mL vial sample (preferably using the sample vial as the sparge vessel), or take one or more fresh core samples from the larger jar sample.

 

If screening results indicate a high analyte level, use the data to predict the required sample mass or methanolic extract dilution needed to achieve sample extract concentration at or near the midpoint of the method calibration range. Note that high concentrations, far exceeding the linear range of the method will normally underestimate true sample concentration.

4.4              Sample storage

To maintain sample integrity, samples should be collected and kept in a container that will not increase or reduce the analyte concentration in the sample (i.e. will not add contaminants or leach them). The sooner the sample is analysed after collection, the more closely the analytical result will reflect the condition of the sample at the time of sampling.

 

Table 1 below lists the recommended containers, maximum holding times and soil conditions for the analytes included in these guidelines. State regulatory agencies may specify different holding times or container types; in which case the jurisdictional requirements should be followed.

 

Long-term storage of field-moist samples has the disadvantage of allowing faster degradation of analytes via microbial activity, particularly if samples are stored at ambient temperatures. Moist samples should be stored at low temperature (≤6°C) and analysed as quickly as possible.

 

Air-dried or oven-dried samples can easily absorb moisture in storage. Immediately after homogenising and partitioning, the prepared samples should be transferred into clearly labelled and sealed containers and stored under dry, relatively cool (<18°C) and low light conditions while awaiting analysis.

 

All unanalysed portions of the sample should be retained for a reasonable amount of time after the dispatch of the analytical report (i.e. at least two months) or until agreed to or advised by the client that they may be discarded.

4.4.1        Holding Times

The holding times in Table 1 are the recommended maximum times before sample extraction. They are taken from a number of sources, and are a guideline only; the integrity of the sample and reliability of results will depend not only on the length of time the sample has been stored, but also on the conditions of sample handling and storage. The effects of storage on sample integrity will be based on the concentration of analyte in the sample, sample temperature, reactions with other compounds that may be present, degradation by microbiological factors, etc. Analytes such as metals and some semi-volatile organics (including PCBs, PAHs) are persistent in the environment and are not likely to change significantly after sampling; analysis slightly outside of these holding times is not likely to cause significant variation in results if samples have been handled and stored correctly. However, all tests should be carried out as soon as practicable after sampling, and according to any jurisdictional requirements.


 

Table 1. Recommended sample containers, holding timesa and condition of soil for analysisb.


Analyte

Containerc

Maximum holding time

Sample condition

Moisture content

- Moisture content only

- Moisture correction

 

- P, PTFE or G

- As for analyte of interest

 

- 14 days

- As for analyte of interest

 

Field-moist

Field-moist

pH

P, PTFE or G

24 hours recommended;

7 days allowed

Air-dry or field-moist, depending on analyte of interest

Electrical conductivity

P or G

7 days

Air-dry or field-moist

Organic carbon

G with PTFE-lined capd

28 days

Air-dry or field-moist

Metals (except Mercury & Chromium VI)

P, PTFE or G

6 months

Air-dry or field-moist

Mercury & Chromium VI

P (AW)d

28 days.

For Cr VI, can hold up to 7 days post-extraction

Field-moist

Cation exchange capacity, exchangeable cations

P (AW)

28 days

Air-dry or field-moist

Chloride (water-soluble)

P, PTFE or G

28 days

Air-dry or field-moist

Bromide (water-soluble)

P, PTFE or G

28 days

Air-dry or field-moist

Cyanide

P, PTFE or Gd

14 days

Field-moist

Fluoride

P or G

28 days

Air-dry or field-moist

Sulfur – total

P, PTFE or G

7 days

Air-dry or field-moist

Sulfate

P, PTFE or G

28 days

Air-dry or field-moist

Sulfide

P or Ge

7 days

Field-moist

Volatile Organics, except for vinyl chloride, styrene, or
2-chloroethyl vinyl ether

G with PTFE-lined lid/septumf

14 days

Field-moist

Vinyl chloride, styrene,

2-chloroethyl vinyl ether

G with PTFE-lined lid/septumf

7 days

Semi-volatile organics, except PCBs, dioxins & furans

G with PTFE-lined lid/septumg

14 daysh

Field-moist

PCBs, dioxins & furans

G with PTFE-lined lid/septumg

28 daysh

Field-moist

 

Notes

a - Recommended maximum time until sample extraction.

b - Sourced from various references including US EPA SW-846 and Australian and international standards

c - Minimum volume of 250 mL. Containers should be free from contamination, either washed as appropriate or use clean food-grade containers.

P = Plastic               G = Glass                PTFE= polytetrafluoroethylene               AW = Acid-washed                SR = Solvent rinsed.

d - Store in the dark.

e - Add sufficient 2M zinc acetate to fully cover surface of solid with minimal headspace; refrigerate (<6°C) (see SW-846 Method 5021, Method 9030B).

f - The vials and septa should be washed with soap and water and rinsed with distilled deionised water. After thoroughly cleaning the vials and septa, they should be placed in an oven and dried at 100°C for approximately one hour. Food-grade containers may also be used without the need for cleaning. Containers should be free from contamination.

g - Containers used to collect samples for the determination of semi-volatile organic compounds should be washed with soap and water then rinsed with methanol (or isopropanol) (see US EPA SW846 Chapter 4 Section 4.1.4 for specific instructions on glassware cleaning). Food-grade containers may also be used without the need for cleaning. Containers should be free from contamination.

h - Once the SVOC is extracted, the extract can be held for 40 days.

4.5              Documentation and reporting

4.5.1        Sample receipt report

Upon receipt of sample, laboratories should issue a Sample Receipt Report detailing the condition of samples, including temperature upon receipt (recorded and reported per individual sample delivery container) and sample preservation status, and chain-of-custody details. As well as commencing a record for the future analytical report, this provides an opportunity for the analyst and sample submitter/site investigator to confirm their requirements.

4.5.2        Analytical report

The analytical report should describe all information and data relevant to the analysis of the sample. This includes:

 

(a) Requirements for AS ISO/IEC 17025–2005:

·                     a title

·         the name and address of the analytical laboratory (including accreditation details from NATA or one of its mutual recognition agreement partners)

·         the analytical report number (a unique identification)

·         sample identification (a unique identification for each sample)

·         the identity of the test method and any deviations from it analytical results

·         a statement of uncertainty where relevant to the validity or application of results or where uncertainty affects compliance to a specification limit, or where requested by the client. (The statement of uncertainty may be implicit in the results presented, e.g. a result may be rounded to the nearest 100 or 1000 indicating an uncertainty of 50 or 500 respectively.)

·         any other information specified by the test method or statutory regulation

·         a statement of conditions pertaining to reproduction of the report

·         the name(s), function(s) and signature(s) or equivalent identification of person(s) authorising the test report

·         the date of analytical report issue.

Plus

(b) Other relevant information including:

·         the date the sample was received

·<