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 ga s chromatography-mass spectrometry with electron impact ionization was developed. The preconcentration of 500 ml of water with C-18 and styr ene-divinylbenzene (SDB) allowed the determination of pesticides at lo w-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 w ith C-18 discs. With SDB discs the recoveries were >85% for most compo unds. 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 sensi tivity with negative chemical ionization was obtained for most compoun ds.