DETERMINATION OF NATIONAL SURVEY OF PESTICIDES ANALYTES IN GROUNDWATER BY LIQUID-CHROMATOGRAPHY WITH POSTCOLUMN REACTION DETECTION

Multi-residue methods for pesticides in water were developed using liquid chromatography (LC) with postcolumn reaction detection. Over 100 analytes from the US Environmental Protection Agency's National Survey of Pesticides in Drinking Water Wells were screened for response using postcolumn photolysis followed by fluorescence (PFD), electrochemical (PED) or conductivity (PCD) detection. LC-PED and LC-PFD are suitable for multi-residue pesticide determinations in groundwater. These two detection methods are complementary as PED responds to several sulfur-containing pesticides whereas PFD responds to many nitrogenous pesticides. Approximately half of these analytes could be determined in low nanograms amounts using these two detection systems and multi-residue separations with gradient reversed-phase LC are demonstrated. The LC-PCD system tested was not suitable for sensitive, multi-residue determinations and further examination of this technique is recommended using the commercial PCD instrument.