Determination of Atrazine and Hydroxyatrazine in Agricultural Runoff Waters by Liquid Chromatography and Fast Atom Bombardment-High Resolution Mass Spectrometry

Agricultural surface water samples were collected after the first 2 major runoff events in 1994 for determination of atrazine (ATR, 2-chloro-4-ethylamino-6-isopropylamino-s-triazine) and hydroxyatrazine (HA, 2-ethylamino-4-hydroxy-6-isopropylamino-striazine). After addition of. ¹³C₃-labeled ATR and ¹³C₃-labeled HA as internal standards, the chemicals were quantitatively extracted and eluted from water samples by liquid-solid extraction with a carbon black cartridge. Liquid chromatography and fast atom bombardment-high resolution mass spectrometry were used to analyze the sample extracts. Concentrations of ATR ranged from 8.2 to 15.1 parts per billion (ppb) in the samples collected after both runoff events from a highly agricultural watershed in south-central Nebraska. HA concentrations ranged from 0.25 to 2.7 ppb in the water samples. Results obtained from both analytical procedures agreed within a 15% deviation. As predicted from runoff events, the highest levels occurred in samples from the first collection on June 24,1994, for both ATR and HA, whereas samples collected on July 5,1994, contained much lower levels of HA.