DETERMINATION OF PERMETHRIN AND CYFLUTHRIN IN WATER AND SEDIMENT BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY OPERATED IN THE NEGATIVE CHEMICAL-IONIZATION MODE

Gas chromatography-mass spectrometry operated in the negative chemical ionization mode (GC-NCI-MS) with selected-ion monitoring (SIM) showed both high sensitivity and excellent specificity for permethrin and cyfluthrin. The detection limit for both permethrin and cyfluthrin was 50 fg, whilst a linear response was observed from 50 fg to 80 pg. A sample extraction method using an ultrasonic bath was developed enabling simultaneous processing of multiple samples. Good percentage recoveries of both permethrin and cyfluthrin from spiked sediments were obtained (97.3 +/- 4.8% and 93.9 +/- 5.3%, respectively) and sample clean-up was avoided. These methods were also sucessfully applied to samples obtained from a contaminated ecosystem, the highest concentrations recorded in water and sediment samples were 0.048 mu g 1(-1) and 305 mu g kg(-1), respectively.