Investigations Into Methods for the Extraction and Detection of Chlorinated Pesticides in Aquatic Animals.

Abstract

Methodologies for the extraction and analysis of chlorinated pesticides from aquatic species are reviewed and compared. New multiresidue isolation techniques using Matrix Solid Phase Dispersion (MSPD) are presented for the extraction and subsequent gas chromatographic, electron capture detector determination of 14 chlorinated pesticides ($\alpha$-BHC, $\beta$-BHC, lindane, heptachlor, aldrin, heptachlor epoxide, p,p$\sp\prime$-DDE, dieldrin, endrin, 4,4$\sp\prime$-DDD, endrin aldehyde, p,p$\sp\prime$-DDT, endosulfan sulfate, and methoxychlor) from crayfish (Procambarus clarkii) hepatopancreas, oysters (Crassostrea virginica) and fish muscle tissues. Pureed crayfish hepatopancreata or oysters or fish muscle fillets (0.5-g aliquots) were fortified with the 14 pesticides, plus $\delta$-BHC as an internal standard, before being blended with 2 g of C$\sb{18}$ (octadecylsilyl)-derivatized silica. The C$\sb{18}$/sample matrix blend and 2 g of activated Florisil comprised an extraction column from which the pesticides were eluted by addition of 8 mL of eluting solvent (acetonitrile or an acetonitrile/methanol blend). Two microliters of the eluate were then directly analyzed by gas chromatography with electron capture detection. Unfortified blank controls were treated similarly. The eluate contained all the pesticide analytes and was free of interfering co-extractants at most fortification levels for the different sample types. Correlation coefficients for the 14 extracted pesticide standard curves (linear regression analysis), average relative percent recoveries over the range of concentrations examined, inter-assay variability and intra-assay variability indicated that the MSPD methodology allowed for the successful extraction and determination of the 14 chlorinated pesticides at levels of 60-2000 ng/g in the sample types tested. Compared to previous methods for the analysis of chlorinated pesticides in aquatic species the techniques and methodology presented here reduce analytical response time, solvent use, solvent waste and disposal and technician exposure. The methods presented are generic and may also prove applicable to the MSPD analysis of a wide range of environmental pollutants. These methods could form the basis for a new approach to pollutant analysis and should be considered as possible replacements for existing methodology utilized by monitoring agencies.