SCREENING OF NONFATTY FISH FOR ORGANOCHLORINE PESTICIDE-RESIDUES BY SOLID-PHASE EXTRACTION CLEANUP - INTERLABORATORY STUDY

Six U.S. Food and Drug Administration laboratories participated in an interlaboratory trial of a solid-phase extraction cleanup method for d etermination of pesticides in nonfatty seafood products. The participa nts analyzed control and fortified (about 0.050 ppm lindane, heptachlo r epoxide, p,p'-DDE, and endrin) croaker and flounder samples and a se a trout sample containing incurred p,p'-DDE residues. Mean recoveries of the fortified residues from the fish ranged from 89.1 to 107.8%. Th e within-laboratory coefficients of variation (CVs) ranged from 4.2 to 8.5%, and the among-laboratory CVs ranged from 10.9 to 26.5%. The 6 l aboratories reported a mean value of 0.040 ppm p,p'-DDE in a fish samp le which contained incurred residues. The same value (0.040 ppm) was o btained by using official methodology. The within-laboratory CVs range d from 3.5 to 18.3%, and the among-laboratory CV was 17.3%.