Extraction and Gas Chromatographic Screening of 14 Chlorinated Pesticides in Crayfish (Procambarus clarkii) Hepatopancreas

Abstract

A multiresidue isolation technique using matrix solid-phase dispersion (MSPD) and gas chromatography/electron capture detection is applied to crayfish (Procambarus clarkii) hepatopancreas for the extraction and determination of 14 chlorinated pesticides (alpha-BHC, beta-BHC, lindane, heptachlor, aldrin, heptachlor epoxide, p,p'-DDE, dieldrin, endrin, 4,4'-DDD, endrin aldehyde, p,p'-DDT, endosulfan sulfate, and methoxychlor). Pureed crayfish hepatopancreata (0.5 g aliquot) are fortified with the 14 pesticides and with delta-BHC as an internal standard before blending with 2 g C18 (octadecylsilyl)-derivatized silica. The C18-hepatopancreas matrix blend and 2 g activated Florisil comprise an extraction column from which the pesticides are eluted by adding 8 mL acetonitrile. Two microliters of the eluate is directly analyzed by gas chromatography with electron capture detection. Unfortified blank controls are treated similarly. The eluate contained all the pesticide analytes and was free of interfering coextractants at most fortification levels. Correlation coefficients for the 14 extracted pesticide standard curves (linear regression analysis) ranged from 0.9685 to 0.9985. Average relative percent recoveries (recoveries for all pesticides ranged from 55 +/- 10.4% to 118 +/- 45.2%, n = 15 for each pesticide) over the range of concentrations examined, interassay variability (7.1 +/- 5.7% to 16.0 +/- 5.6%, n = 15 for each pesticide), and intra-assay variability (0.0-26.2%, n = 5 for each pesticide) indicated that the MSPD methodology allowed for the successful extraction and determination of the 14 chlorinated pesticides at 125-2000 ng/g levels in crayfish hepatopancreas.