Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:13:p3
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 13 (pt 3/9)
Character Range: 855712–858909

method (see Method A2 below (Section 14.3) and Section 11.13).

    13.2.2     Limitations
    * This method does not distinguish between petrogenic and biogenic compounds or synthetic compounds, such as chlorinated solvents; it measures the total recoverable hydrocarbons present, hence it is designated TRH.
    * Excess moisture in sample: the method requires extraction of the sample with methanol, which is soluble in water. Excess moisture can dilute the extraction solvent, increasing the solvent volume thus diluting the extract.
    * High organic carbon content in sample: methanol is a relatively weak solvent for non-polar compounds. Volatile analytes may be retained by matrices containing high organic carbon levels. Surrogates added to extractions may preferably partition onto the carbon matrix.

    13.2.3     Interferences
The method is subject to certain interferences including:
    * highly contaminated samples may cause a carry-over on the instrument
    * laboratory background, including ambient air, carry-over and contaminated soils.

    13.2.4     Principle
A soil sample (>5 g) is extracted with a sufficient volume of methanol, then the methanol is separated from the soil and added to a purging vessel or other equivalent apparatus for determination of volatile compounds, using FID or MS in scan mode.

    13.2.5     Method

13.2.5.1     Apparatus
A gas chromatograph with appropriate detector for hydrocarbon determination. Columns suitable for volatiles, as specified in US EPA Method 8260B (latest version).

13.2.5.2     Reagents and standards
Reagents
Unless otherwise specified, all reagents shall be of analytical grade (AR) and all solvents of chromatography grade. Chromatography grade methanol and organic-free water are recommended, and ultra-pure carrier gas for gas chromatography.

Standards
Internal standard
This solution comprises a suitable compound dissolved in methanol to a suggested concentration of 10 mg/L and should be stored at 4°C. Suitable compounds are specified in US EPA Method 8260B.

Surrogate standard
This standard comprises a methanol solution containing at least one surrogate compound. Suitable compounds include 4-bromofluorobenzene, dibromofluoromethane, toluene-d8. It should be stored at 4°C.

Calibration standard solutions
nC6nC10 TRH Standard (standards for mass selective detector or flame ionisation detector).

Owing to the differential responses of mass spectrometric detectors towards aliphatic and aromatic compounds, it is essential that the standard contains representatives of both groups.

This standard should therefore consist of about 40% aromatic and 60% aliphatic target analytes, in order to be representative of a typical Australian fuel. The aromatic compounds shall comprise the components of BTEX. The aliphatics shall comprise equal proportions of all n-alkanes in the C6C10 range.

These solutions are stable for 6 months when stored at ≤6°C with minimum headspace and away from all possible sources of contamination.

Note: If a different fraction split is requested, the relevant compounds shall be represented in the calibration standard solution.

While it may be possible to store and use