Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:4:p9
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 4 (pt 9/12)
Character Range: 762187–765114

(≤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,