A rapid, simultaneous determination of paraquat and diquat in serum and urine using second-derivative spectroscopy

A rapid, simple method based on second-derivative spectroscopy of the simultaneous analysis of paraquat and diquat in serum and urine is described. Paraquat and diquat in serum were deproteinized with sulfosalicylic acid, and those in urine were reduced with NaOH-dithionite solution. A qualitative and quantitative analysis of reduced paraquat and diquat was made at the amplitude peaks of 396-403 nm and 454-464 nm in the second-derivative spectra, respectively. The entire procedure was completed within about 10 minutes for a serum sample and within about 5 minutes for a urine sample. Application of the proposed method on a poisoned patient is also reported.