Rapid detection of paraquat and diquat in whole blood and urine by gas chromatography-mass spectrometry

Objective To establish a method for determination of paraquat and diquat in whole blood and urine by gas chromatography-mass spectrometry(GC-MS).

Methods Ethyl paraquat was used as internal standard, 10% perchloric acid-ethanol solution (V/V) was added to precipitate protein, and sodium borohydride-nickel chloride(NaBH₄-NiCl₂) were used in the reduction system. The reaction time was 40 minutes at 60℃, then the analytes were extracted with 1.0 mL ethyl acetate, and finally detected in GC-MS selective ion monitoring mode(SIM).

Results The linearities were good within investigated mass concentration ranges of 0.05 to 2.0 μg/mL in the whole blood and 0.02 to 2.0 μg/mL in urine of the paraquat and diquat. The correlation coefficients were 0.999 5 to 0.999 9, the detection limits of the method were 0.004 to 0.008 μg/mL, and the recoveries at three spiked levels were within 94.1%-115.0%, with 1.1%-6.6% of the relative standard deviation (RSD). Paraquat and diquat in blood and urine could be stored for at least 7 days at 4℃.

Conclusion The established method is simple, accurate, and sensitive for rapid detection of paraquat and diquat in whole blood and urine samples.