DETERMINATION OF ATRAZINE IN WATER AT LOW-PARTS-PER-TRILLION AND SUB-PARTS-PER-TRILLION LEVELS BY USING SOLID-PHASE EXTRACTION AND GAS-CHROMATOGRAPHY HIGH-RESOLUTION MASS-SPECTROMETRY

A capillary column gas chromatography/high-resolution mass spectrometry (GC/HRMS) method was developed to determine atrazine in water st low- and sub-parts-par-trillion (ppt) levels. The method fills a need when the detection limits of routine GC, GC/MS, and high-performance liquid chromatography (HPLC) are inadequate for studies to evaluate transport and fate of herbicides in deep ground water systems. Atrazine and the added internal standard [C-13(3)]atrazine were extracted from water samples by solid-phase extraction using a C18 bonded silica cartridge. A column chromatography procedure with Florisil was developed to reduce when necessary further interferences in the sample extract. The analysis was performed by GC/HRMS with the mass spectrometer operated in the selected ion monitoring (SIM) mode; mass profiles were acquired. The precision and accuracy of the method are 15% (relative standard deviation, n = 8) and >85%, respectively, for standard water samples containing atrazine at 1 ppt. The method, which gives detection limits of 200-500 parts-per-quadrillion (ppq), has been successfully used to analyze water samples containing atrazine at concentration levels of 1-500 ppt.