EXTRACTION AND GAS-CHROMATOGRAPHIC SCREENING OF 14 CHLORINATED PESTICIDES IN CRAYFISH (PROCAMBARUS-CLARKII) HEPATOPANCREAS

A multiresidue isolation technique using matrix solid-phase dispersion (MSPD) and gas chromatography/electron capture detection is applied t o crayfish (Procambarus clarkii) hepatopancreas for the extraction and determination of 14 chlorinated pesticides (alpha-BHC, beta-BHC, lind ane, heptachlor, aldrin, heptachlor epoxide, p.p'-DDE, dieldrin, endri n, 4,4'-DDD, endrin aldehyde, p,p'-DDT, endosulfan sulfate, and methox ychlor). Pureed crayfish hepatopancreata (0.5 g aliquot) are fortified with the 14 pesticides and with delta-BHC as an internal standard bef ore blending with 2 g C18 (octadecyl-silyl)-derivatized silica. The C1 8-hepatopancreas matrix blend and 2 g activated Florisil comprise an e xtraction column from which the pesticides are eluted by adding 8 mL a cetonitrile. Two microliters of the eluate is directly analyzed by gas chromatography with electron capture detection. Unfortified blank con trols are treated similarly. The eluate contained all the pesticide an alytes and was free of interfering coextractants at most fortification levels. Correlation coefficients for the 14 extracted pesticide stand ard curves (linear regression analysis) ranged from 0.9685 to 0.9985. Average relative percent recoveries (recoveries for all pesticides ran ged from 55 +/- 10.4% to 118 +/- 45.2%, n = 15 for each pesticide) ove r the range of concentrations examined, interassay variability (7.1 +/ - 5.7% to 16.0 +/5.6%, n = 15 for each pesticide), and intra-assay var iability (0.0-26.2%, n = 5 for each pesticide) indicated that the MSPD methodology allowed for the successful extraction and determination o f the 14 chlorinated pesticides at 125-2000 ng/g levels in crayfish he patopancreas.