Abstract: Objective To establish a new method for the analysis of paraquat in blood and urine by sodium borohydride/nickel chloride chemical reduction gas chromatography/ thermionic specific detector . Methods An initial procedure of precipitation was performed by adding hydrochloric solution with sodium chloride and a mixture of chloroform and ethanol. Then the analyte contained in supernatant was reduced by a reduction system of sodium borohydride and nickel chloride and extracted by acetic ether. Ethyl paraquat (EPQ) was used as internal standard. GC/TSD was used to identify and quantify the analyte. Results The limits of detection(S/N=3) in blood and urine were 0.002 and 0.004 μg/mL, respectively. The linear ranges were 0.050-30.0 μg/mL. Correlation coefficients in blood and urine were 0.999 and 0.998, respectively. The recoveries exceeded 80% both in blood and urine. Conclusion This method is applicable for quantification of paraquat in biological fluids.

Key words: forensic toxicology, paraquat, blood, urine, sodium borohydride/nickel chloride chemical reduction, GC/TSD