ICES/IOC intercomparison exercise on the determination of petroleum hydrocarbons in biological tissues (mussel homogenate)
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A homogenate was prepared from approximately 4000 Mytilus edulis sampled near the municipal sewer outfall of Boston, Massachusetts, USA. Subsamples were placed in jars. Then a set of subsamples were freeze-dried. Both wet homogenate and freeze-dried homogenate samples were checked for non-homogeneity by analyses of randomly selected subsamples by the WHOI coordinating laboratory. Three randomly selected freeze-dried subsamples were distributed to each of 50 participating laboratories from 24 countries. Twenty-two laboratories reported UV-fluorescence data giving x=2410-6 g chrysene equivalents g-1 dry wt 2410-6 g g-1 dry wt for a100% r.s.d. Twenty laboratories reported UV-fluorescence data in Arabian Light Crude Oil equivalents; x=23510-6 g g-1 dry wt 234 for a 98% r.s.d. Between 22 and 30 laboratories reported data for n-alkanes, pristane and phytane determined by GC analyses giving between 69% and 297% r.s.d. depending on the compound. Elimination of outliers reduced the range of r.s.d.'s to 67 to 104% r.s.d. A similar experience was noted for data for individual polynuclear aromatic hydrocarbons when combining data from HPLC, GC, and GCMS analyses. There is a need for much improvement for within and between laboratory precision. 1988.
