Distribution of Chlorinated Hydrocarbon Pesticides and PCBs in the ...

3.2.2 Blanks
Procedural blanks (i.e. the analysis performed without the
introduction of a sample) were used to determine the detection
and quantification limits (section 3.1.9). For each of the
substrate types ( XAD columns, glass fibre filters, polyurethane
plugs, extracts or biota), consistent and minimal procedural
blanks were required before samples could be analysed. Routine
solvent and reagent blanks were run to check for interferences
and monitor contamination. Field blanks were performed on
substrates (i.e. filters, polyurethane plugs and XAD columns)
prepared with the sample substrates, transported to and from the
field with the samples.
3.2.3 Replicates
Replicates or duplicates were included at all stages sf
the analyses, including replicate sampling, extraction and GC
analysis. The precision estimated from these replicates is
specific to the sample type and stage of replication and is
discussed for each sample type in the following section.
3.2.4 Quality Assurance
Where available, standard reference materials or
intercalibration homogenates were analysed to verify analytical
procedures. Intercalibration samples were also collected for
independant analysis by two other laboratories specialising in
sampling air and snow for trace level chlorinated hydrocarbons.
Other quality assurance and quality control measures which
were specific to each type of analysis are described in the
following sections.
4s
4%
4#