[Analysis of bialaphos and its active metabolite L-glufosinate in biological specimens by HPLC]

The symptoms of acute poisoning caused by ingestion of bialaphos (BIAL), an ingredient of herbicide, are supposed to be due to the L-glufosinate (L-GLUF), which is formed by the degradation of bialaphos. To elucidate the pharmacokinetics of BIAL and L-GLUF, we attempted a simultaneous analysis of BIAL and L-GLUF in biological samples by exploiting a reversed phase HPLC method. The derivatization reaction of BIAL and L-GLUF using (+) -1- (9-fluorenyl) ethyl chloroformate was completed in 30 min at 40 degrees C and both derivatives were stable for 48 hr at 25 degrees C. A fluorescence detector were used for HPLC; the exicitation wavelength was set at 265 nm and the emission wavelength at 315 nm. Respective calibration curves prepared by adding BIAL and L-GLUF to serum were linear within ranges of 0.01-10.0 and 0.005-10.0 microg/mL in derivatived liquid samples for introducing into HPLC. The lower limits of detection for BIAL and L-GLUF were 0.005 and 0.001 microg/mL, respectively. An 83-year old male who ingested approximately 350 mL of Herby Liquid, a herbicide containing 18% BIAL and 82% surfactant, in an attempt to commit suicide developed delayed respiratory depression and seizures. L-GLUF was detected in the serum of the patient 2.7 hr after ingestion, but BIAL was not. The change in serum L-GLUF concentration measured over time was consistent with a 2-compartment model, with a distribution half-life of 1.70 hr and an elimination half-life of 6.03 hr.