DETERMINATION OF TRIAZINE HERBICIDES IN SURFACE AND DRINKING WATERS BY OFF-LINE COMBINATION OF LIQUID-CHROMATOGRAPHY AND GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

Mass spectra of 12 triazines were obtained by electron impact (EI), positive-ion chemical ionization (PCI) and negative-ion chemical ionization (NCI) using methane and isobutane as reagent gases. EI mass spectrometry is more sensitive than PCI and NCI, although the chemical ionization modes increase selectivity markedly. A pre-column packed with polymer stationary phase was employed to preconcentrate surface and drinking water samples. After desorption of the analytes with ethyl acetate, an aliquot was injected directly into the GC-MS system. Atrazine and simazine were found in these samples at 10-80 ppt levels. The limits of detection for both herbicides were below 10 ppt in drinking water.