Abstract:

A novel method has been developed for the rapid extraction and determination of eight defoliants including thidiazuron, butiphos, methabenzthiazuron, abscisic acid, carfentrazone-ethyl, diuron, paraquat, and pyrithiobac-sodium in cotton by accelerated solvent extraction (ASE) coupled with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The defoliants in cotton were extracted by ASE and the extracts were dried by a rotavapor, then redissolved in the solvents of acetonitrile and water (1:9, v/v). The chromatographic analysis was performed on an Acquity UPLC^® HSS T3 column (50 mm×2.1 mm, 1.8 μ m) by a gradient elution employing of acetonitrile and 0.05% (v/v) formic acid as mobile phases. The analytes were detected by electrospray ionization (ESI) tandem mass spectrometry with multiple reaction monitoring (MRM) in positive ion mode. Good linearities (r >0.99) were observed between 0.01 and 0.3 mg/L for all the compounds. The recoveries and relative standard deviations (RSDs) were obtained by spiking untreated samples with the eight defoliants at 0.1, 0.5 and 1.0 mg/kg. The average recoveries of the eight defoliants were from (84.18±8.04)% to (95.99±6.76)%. The precision values expressed as RSDs were from 7.04% to 10.60% (n=6). The limits of detection were 0.8-29 μ g/kg and the limits of quantification were 2.5-96 μ g/kg for the analytes. The results showed that the method is simple, rapid, sensitive and accurate, and is suitable for the quantitative determination and confirmation of the eight defoliants in cotton.

Key words: accelerated solvent extraction (ASE), cotton, defoliants, ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS)