DETERMINATION OF VARIOUS PESTICIDES USING MEMBRANE EXTRACTION DISKS AND GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

A method for the determination of a group of pesticides in water by gas chromatography-mass spectrometry with electron impact ionization was developed. The preconcentration of 500 ml of water with C-18 and styrene-divinylbenzene (SDB) allowed the determination of pesticides at low-mu g/l levels. The use of SDB membrane extraction discs gave a large increase in the recovery of aldrin compared with the value obtained with C-18 discs. With SDB discs the recoveries were >85% for most compounds. The limits of detection were between 0.06 and 0.2 mu g/l in the full-scan mode. The mass spectra under positive and negative chemical ionization conditions with methane were also obtained and higher sensitivity with negative chemical ionization was obtained for most compounds.