Solid-phase microextraction of nitrogen and phosphorus-containing pesticides from water and gas chromatographic analysis

Solid-phase microextraction (SPME), a single-step solvent-free extraction, followed by gas-liquid chromatography(GC) employing a nitrogen-phosphorus detector (NPD) and mass spectrometry (MS) was evaluated for the measurement of the 46 nitrogen- and phosphorus-containing pesticides of U.S. EPA Method 507. Effects of pH, ionic strength, methanol content, and temperature on extraction were determined. Analytes were extracted into a bonded polydimethylsiloxane phase coated on a fused-silica fiber and then thermally desorbed in a GC injector and analyzed. Absorption-time and absorption-concentration profiles were obtained for each SPME-extractable pesticide. When analyzed by SPME GC/ NPD or by SPME GC/MS, 34 and 39 pesticides, respectively, were measured at levels lower than the EPA method detection limits and precision requirements. This method was applied to the analysis of contaminated well water, watershed, and streamwater and compared to U.S. EPA Method 507 findings. These results demonstrate that SPME is a valuable tool for the rapid screening of 39 EPA Method 507 nitrogen- and phosphorus-containing pesticides in water.