SIMULTANEOUS DETERMINATION OF FLUPYRAZOFOS AND ITS METABOLITE 1-PHENYL-3-TRIFLUOROMETHYL-5-HYDROXYPYRAZOLE AND FLUPYRAZOFOS OXON IN RAT PLASMA BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH ULTRAVIOLET ABSORBENCY DETECTION

An isocratic high-performance liquid chromatography (HPLC) system with UV detection was developed for simultaneous determination of flupyraz ofos and its metabolites, 1-phenyl-3-trifluoromethyl-5-hydroxypyrazole and flupyrazofos oxon, in rat plasma. Optimal analytical conditions i nvolved an analytical cartridge column consisting of a phenyl bonded p hase, a mobile phase of 50 mM phosphate buffer (pH3.0)-acetonitrile (4 0:60, v/v) and a UV detection wavelength of 232 nm. Under these condit ions the peaks of flupyrazofos and its metabolites were all well separ ated and the total time for complete separation was less than 12 min. The limit of quantitation was 40 ng/ml for flupyrazofos and 20 ng/ml f or PTMHP. Recoveries from rat plasma were higher than 90%. Following i ntravenous administration of flupyrazofos, the method has been success fully applied in a toxicokinetic study in rats involving plasma sample s. Therefore, the current method is a valuable analytical tool for inv estigating the metabolism and toxicokinetics of flupyrazofos. (C) 1998 Elsevier Science B.V. All rights reserved.