This initial result should be presented to justify the subsequent dilution of the extract. This allows an evaluation of the surrogate recovery in the extraction step to determine if the processing was correctly done and verifies that concentrations exceeded calibration limits. The dilution is done on the extract, not on the original sample. Yet, data are presented on diluted samples with apparently good surrogate recoveries and low PCB levels indicating that a smaller sample was taken initially. The method requires a total transfer of the supplied sample, plus a solvent rinse of the sample container that is added to the extraction vessel.
Any debris carried into the extractant is removed in cleanup steps.
The field notes do not indicate any problem getting sufficient water. Sample LL1445 was taken from a 55-gallon drum and only 900n ml was used. LL1442 had three 55-gallon drums as a source, yet about 500 ml was used. Another problem with using a smaller volume is that it distorts surrogate recovery data. Spiking the surrogate into a volume lower than required, artificially elevate recovery results.