Pesticide analysis by high-performance liquid chromatography using the direct injection method

HPLC with direct injection was examined as a simple and rapid method for the determination of pesticides in water. Fifteen pesticides listed in the Japanese standard and guidelines for potable water were separated successfully with an ODS column and acetonitrile-phosphate buffer as the mobile phase. All pesticides were separated simultaneously under gradient elution conditions: [CH3CN]=30% at 0 min to 80% at 60 min, flow-rate = 1.5 ml/min. However, isocratic elution conditions were required for large injection volumes. Even with a 5-ml injection, successful chromatograms were obtained and all pesticides were detected at the ppb or sub-ppb level. A 5-ml environmental water sample was also injected after filtration with a glass-fibre filter (0.3 mu m) and propyamide, MEP and diazinon were observed at 0.07, 1.3, 1.1 mu g/l, respectively.