Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:13:p6
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 13 (pt 6/9)
Character Range: 864071–867189

between >nC10 and nC40 alkanes. The method extracts target component hydrocarbons such as PAHs. If the presence of PAHs is suspected, target analysis techniques are preferred for risk assessments. Volatile hydrocarbons with lower boiling points than nC10 or heavy petroleum products (boiling points >nC40) will not be quantitatively determined using this method.

Where significant levels of non-TPH interferences are suspected, a silica gel clean-up procedure is included as an optional but recommended clean-up step (with the results qualified as 'TRH-silica').

    13.3.2     Limitations
The method cannot be used to provide quantitative data for the nC6 to nC10 hydrocarbon range, as it allows loss of the most volatile components in the sample, mainly during the weighing and chemical drying steps. For quantitative analysis of nC6 to nC10 hydrocarbons, refer to Method A1 in this Schedule.

    13.3.3     Interferences
Interferences may be caused by any organic compounds that are soluble in the extracting solvent and that elute from the GC under the conditions used. These may include vegetable and animal oils and fats, chlorinated and other solvents, plasticisers, etc. The use of silica to adsorb polar compounds may reduce these interferences.

Impurities in the extracting solvent, drying agents and silica will interfere, and can be reduced by the use of high purity solvents. Laboratory blanks should be analysed with each batch of samples.

Carry-over from previous highly contaminated samples extracted in the same glassware may cause spurious elevated results, which can be minimised through efficient cleaning of all glassware, syringes, etc.

    13.3.4     Principle
A soil sample (>10 g) is treated with anhydrous sodium sulfate then extracted into a minimum of 20 mL 1:1 DCM:acetone. The sample is extracted by mechanical end-over-end shaking for a minimum of 1 hour or other suitably validated extraction techniques (ASE©, horn probe ultrasonication, mechanical wrist action shaker or soxhlet extraction). Where non-TPH interferences are suspected, a silica gel treatment step is recommended.

The extract is analysed with a phenyl polymethylsiloxane phase column containing up to 5% polymethylsiloxane using a GC equipped with an FID. The results are reported as the amount of hydrocarbon in three defined fractions – >nC10nC16, >nC16nC34 and >nC34nC40.

    13.3.5     Method

13.3.5.1     Apparatus
    * Gas chromatograph with FID
    * Column: non-polar or semi-polar bonded phase capillary column is strongly recommended (polymethylsiloxane up to 5% phenyl polymethylsiloxane)
    * Integrator or computer and integration software
    * Volumetric pipettes and glassware—they should all be regularly calibrated and a calibration record maintained.

13.3.5.2     Reagents and standards
Reagents
All reagents used in this method should be reagent grade or higher.

Dichloromethane (DCM) and acetone should be high purity and give no interference peaks by GC-FID.

Anhydrous sodium sulfate may contain plasticisers leached from plastic storage containers;

each batch should be checked