DETERMINATION OF DIDEALKYLATRAZINE IN WATER BY GRAPHITIZED CARBON-BLACK EXTRACTION FOLLOWED BY GAS-CHROMATOGRAPHY HIGH-RESOLUTION MASS-SPECTROMETRY

A highly specific and sensitive method has been developed for determin ing trace levels of didealkylatrazine (DDA), one of the dealkylated pr oducts of atrazine degradation occurring in ground and surface waters. The analyte was isolated efficiently from deionized water and ground water by liquid-solid extraction via a graphitized carbon black cartri dge, and the recoveries are greater than 80%. These recoveries are an order of magnitude greater than those achieved by liquid-liquid extrac tion (dichloromethane) and solid-phase extraction with a C-18 bonded s ilica cartridge. Analysis was performed by gas chromatography-high res olution mass spectrometry; mass profiles were acquired in the selected ion monitoring mode. A precision of < 20% (relative standard deviatio n) was obtained for six deionized water samples fortified with DDA at the 500 ppt level. The average accuracy is 85% of the true amount for the deionized water samples. The detection limit for a 200-ml sample i s 2 ppt. The method has been successfully applied to determine DDA in ground water.