Wide-spread and systematic errors in the analysis of soils for polychlorinated biphenyls. Part 2. Comparison of extraction systems

Abstract

The various factors in the separation of polychlorinated biphenyls from soil for determination by gas chromatography were compared using data from an inter-laboratory study, including extraction equipment, solvents and clean-up procedures. These were compared for accuracy and precision using five soils spiked with Aroclor 1260 at concentrations covering a range of four orders of magnitude. Results from laboratories using Soxhlet extraction were significantly more accurate than those obtained using sonication, especially at higher concentrations, but with equal precision. Results from laboratories using non-polar solvents showed significantly lower accuracy than results with more polar solvents, with equal precision. Results from laboratories using Florisil column clean-up were significantly more accurate and precise at lower concentrations than those from laboratories using no clean-up procedure.