title: Gas chromatographic-mass spectrometric method for the determination of the herbicides paraquat and diquat in plasma and urine samples.
abstract: In the present work, a method was developed and optimized aiming to determinate the herbicides paraquat (PQ) and diquat (DQ) in human plasma and urine samples. An initial procedure of chemical reduction of the analytes by adding NaBH4 directly in the buffered samples (pH 8.0) was performed. This procedure was necessary to convert the quaternary ammonium substances into more volatile compounds for gas chromatographic analysis. The reduction compounds were extracted with C18 cartridges (solid-phase extraction). Ethyl paraquat (EPQ) was used as internal standard (IS). Gas chromatography-mass spectrometry (GC-MS) was used to identify and quantify the analytes in selected ion monitoring (SIM) mode. The limits of detection were 0.05 mg/l for both PQ and DQ. By using the weighted least squares linear regression (1/x1/2 for plasma and 1/y for urine), the accuracy of the analytical method was improved at the lower end of the calibration curve (from 0.1 to 50 mg/l; r>0.98). This method can be readily utilized as an important tool to confirm the suspicion of PQ and/or DQ poisoning and evaluate the extent of the intoxication.
authors: Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, USP, Av. Professor Lineu Prestes, 580 B13B CEP: 05508-900, São Paulo, SP, Brazil.
authors: Rafael Menck
authors: RM
authors: de Almeida
authors: Mauricio
authors: M
authors: Yonamine
mesh_terms: D004178:Diquat / Q000097:blood* / Q000737:chemistry / Q000652:urine*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006540:Herbicides / Q000097:blood / Q000737:chemistry / Q000652:urine; D006801:Humans; D015394:Molecular Structure; D010269:Paraquat / Q000097:blood* / Q000737:chemistry / Q000652:urine*; D015203:Reproducibility of Results
chemical_list: D006540:Herbicides; D004178:Diquat; D010269:Paraquat