Preservation and analytical procedures for the analysis of chloro-s-triazines and their chlorodegradate products in drinking waters using direct injection liquid chromatography tandem mass spectrometry

A direct injection, liquid chromatography tandem mass spectrometry (LC–MS/MS) method has been developed for the analysis of the chloro-s-triazine herbicides and their degradates in finished drinking water. The target compounds in the method were selected based on their inclusion in a common mechanism group (CMG) because of their ability to induce a similar toxic effect through a common mechanism of toxicity. The target list includes the chloro-s-triazines (atrazine, simazine, cyanazine, and propazine) and their dealkylated degradates (desethylatrazine, desisopropylatrazine, and diaminochlorotriazine). Potential matrix effects are minimized by the use of individual isotopically enriched internal standards. Analyte stability in finished chlorinated drinking water samples is ensured through careful selection of proper dechlorinating and antimicrobial reagents and through buffering sample pH. In the absence of proper dechlorination, the target analytes were found to degrade over a short period of time, even under refrigerated storage conditions. The final method has adequate sensitivity to accurately detect all target analytes at or below 0.1 μg/L and displays sufficient precision and robustness to warrant publication as EPA Method 536.