Simultaneous determination of paraquat and diquat in human plasma using HPLC with chemiluminescence detection

Abstract

Paraquat and diquat are most widely used herbicides, but they have significant acute toxicity to humans. The aim of the present study is to develop a high-performance liquid chromatography (HPLC)-chemiluminescence (CL) detection system that allows simultaneous determinations of paraquat and diquat. The proposed HPLC-CL method is useful to evaluate health risk and origin of paraquat and diquat. Paraquat and diquat are separated by silica-gel HPLC, and CL detection is based on the luminol-detecting CL of superoxide anion radicals, which are generated by the redox cycle reaction between paraquat or diquat and dithiothreitol. Under the optimum conditions, paraquat and diquat were detected at 16.0 and 13.0 min, respectively, and the limit of detection (S/N=3) was 40 nM for paraquat and 53 nM for diquat. Using the proposed HPLC-CL method, the peaks corresponding to paraquat and diquat in human plasma could be selectively detected on chromatograms without any interference from plasma components by simple deproteinization with 50% trichloroacetic acid.