SYNTHETIC PYRETHROID INSECTICIDES IN FISH - ANALYSIS BY GAS-CHROMATOGRAPHY MASS-SPECTROMETRY OPERATED IN THE NEGATIVE-ION CHEMICAL-IONIZATION MODE AND ELISA

Brown trout (Salmo trutta) were captured from a headwater stream conta minated with moth-proofing agents. Synthetic pyrethroid residues withi n the tissues were obtained by ultrasonic extraction and examined by g as chromatography-mass spectrometry operated in the negative ion chemi cal ionization mode (GC/NCI-MS). Both permethrin and cyfluthrin had be en bioaccumulated by the fish and the mean concentrations (+/- standar d deviation) recorded were 2046 (+/-203) mu g kg(-1) and 25.4 (+/-46.9 ) mu g kg(-1) respectively. The concentrations of these pyrethroids ar e the highest recorded for freshwater fish captured from a natural eco system. At the time of sampling, permethrin could be detected within t he stream water (0.034 mu g l(-1)) while cyfluthrin could not. A mean relative bioconcentration factor of approximately 60 000 was derived f or the brown trout which was also greater than any previously determin ed for freshwater fish The fish tissue extracts were also analyzed thr ough use of an ELISA for permethrin. The ELISA reported consistently l ower concentrations than those obtained by GC/NCI-MS. This was attribu ted to analyte losses during preparation of the sample extracts in a f orm suitable for incorporation into the ELISA. The concentrations obta ined by ELISA were significantly correlated with those obtained by GC/ NCI-MS (R(2) = 0.985, n = 5). Overall, the ELISA appeared to be suitab le for the detection of permethrin in fish when present at concentrati ons in excess of the maximum residue level suggested for many foods by the Commission of the European Economic Community.