Analysis of paraquat, diquat and two diquat metabolites in biological materials by high-performance liquid chromatography.

The determination of paraquat, diquat and two metabolites of diquat in biological materials was developed using high-performance liquid chromatography combined with UV and fluorescence detectors. Paraquat, diquat and internal standards (ethyl viologen and o-acetamidophenol) were detected by the UV detector. Diquat-monopyridone and diquat-dipyridone were monitored by the fluorescence detector. Paraquat, diquat, diquat-monopyridone and ethyl viologen were effectively extracted from blood, liver and brain, using a Sep-Pak C(18) cartridge. Diquat-dipyridone and o-acetamidophenol were extracted with methanol. Paraquat and diquat at a concentration range of 0.1-10 microg/ml (or g), and diquat-monopyridone and diquat-dipyridone at a concentration range of 0.01-1 microg/ml (or g) in biological material were determined with high accuracy and precision. The detection limits of paraquat, diquat, diquat-monopyridone and diquat-dipyridone were 1, 1, 0.02 and 0.02 ng, respectively, as an injection amount. This method was applied for toxicological examination of a case of suspected paraquat and diquat intoxication. The analysis of the metabolites of diquat was helpful for the estimation of the elapsed time from ingestion to death.