Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:4:p5
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 4 (pt 5/12)
Character Range: 750408–753413

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,