Schedule B3 - COAG Standing Council on Environment and Water

This guideline recommends certain extraction procedures or complete methods; however, 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.
3.2.1 Confirmation of organic compounds (for non-specific techniques)
Where non-specific analytical techniques are used, for example, gas chromatography (GC) or
high performance liquid chromatography (HPLC), the identity of organic compounds should be
confirmed by one of the methods in the NATA Field Application Document ISO/IEC17025
FAD (NATA 2007); 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. derivatisation technique).
A GC/MS or HPLC/MS 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 8270D) are met:
• the intensities of the characteristic ions of the compound in the sample must maximise in the
same scan, or within one scan, as that of the reference compound
• the relative retention time (RRT) of the sample component is within ±0.06 of the RRT of the
standard component
• the relative intensities of the characteristic ions (see Note immediately below) in the sample
all agree within 30% of the relative intensities of these ions on the reference compound
spectrum.
Note: The characteristic ions are defined as the three ions of greatest intensity in the
reference compound spectrum.
3.3 Assessing analyte leachability and bioavailability
Some methods for assessing mobility and availability of soil chemicals are based on methods
designed for agronomic studies and land surveys and hence are only applicable to soils
expected to have relatively low contaminant concentrations, for example, 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.
Leachability of contaminants is a more useful parameter for assessing site contamination. This
<strong>Schedule</strong> describes two leachability methods for assessing the mobility of common metal
contaminants. 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.
<strong>Schedule</strong> <strong>B3</strong> - Guideline on laboratory analysis of potentially contaminated soils 5