Determination of Tiadinil and Its Metabolite in Flue-Cured Tobacco

A novel and sensitive method was developed for the determination of residues of tiadinil and its metabolite, 4-methyl-l,2,3-thiadiazole-5carboxylic acid, in flue-cured tobacco. The pesticides were extracted with acetone and purified by gel permeation chromatography and solid-phase extraction. Analysis was performed by ultra-performance liquid chromatography–tandem mass spectrometry in negative ionization mode. Two precursor–product ion transitions were monitored for both compounds in the multiple reaction monitoring mode. Quantification was conducted by using matrix-matched standard calibration. Recovery values of the proposed method for tiadinil ranged from 72.5 to 98.2%, with relative standard deviations ranging from 3.8 to 9.5%; recovery values for 4-methyl-l,2,3-thiadiazole-5-carboxylic acid ranged from 75.4 to 103.3% with RSDs ranging from 3.7 to 9.3%. The limit of quantification for both compounds was 0.01 mg/kg. This method is valuable for residual analysis, quality control and monitoring of tiadinil and its metabolite, 4-methyl-l,2,3thiadiazole-5-carboxylic acid, in tobacco.