Sample preservation container selection

While field crews collect the samples, the chemist verifies their types and quantities by comparing the COC Forms, Sample Tracking Logs, and other field records to the SAP specifications. The chemist interacts with the field crews for the resolution of errors in the sampling point selection, sample containers and preservation or COC Form errors. The chemist also serves as a point of contact with the laboratory, if any technical issues arise during sample analysis. 

Methods for Determining Biomarkers of Exposure and Effect. Sensitive and selective methods are available for the detection and quantitative measurement of tin after the sample matrix in which it is contained has been properly treated. Atomic spectrometric techniques provide methods for the determination of tin that have low detection limits, are highly specific, and are readily available (Angererand Schaller 1988 AOAC 1984b Kneip and Crable 1988 NIOSH 1984a). Methods for the determination of specific compounds that contain tin are more difficult and less well developed than are methods for the determination of total tin, but this is an important concern because of the widespread use of organotin compounds as preservatives in industry and in other applications. 

The vials, which are either prepared by the laboratory or obtained from a supplier, are certified precleaned autosampler vials with PTFE-lined septum caps and magnetic stir bars inside. The vials may contain 5 ml of analyte-free water or be empty. The vials with water may be unpreserved or be preserved with approximately 1 g of sodium bisulfate to pH < 2. (We need to select the type of the preservation, which is appropriate for the soil to be sampled.) The laboratory or the manufacturer will weigh the prepared vials with labels attached, record the weight on the label, and ship them to the field sampling team. 

Buried mat samples were collected from the sabkha, in pits or along artificial channels. They were selected to correspond to the modem mat samples in terms of depositional environments. The buried mat sample used for detailed geochemical studies has been collected from the sabkha two kilometers inland at a depth of 60 cm. Its sedimentary structure is well preserved and it contains 2% TOC. 

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