Stereoselective separation and determination of quizalofop-ethyl in tobacco by ultra-performance convergence chromatography with tandem mass spectrometry

The purpose of this study was to develop and validate a novel and sensitive method for simultaneous enantiomeric analysis of quizalofop-ethyl in tobacco using ultra-performance convergence chromatography with tandem mass spectrometry (UPC 2 -MS/MS). Sample preparation prior to UPC 2 -MS/MS analysis followed a QuEChERS (quick, easy, cheap, effective, rugged and safe) method. The UPC 2 -MS/MS method used an Acquity UPC 2 Trefoil CEL2 column with a mobile phase of CO 2 and methanol. The injection volume was 2 μL and run-time was 6 min with the mobile phase running at 2.0 mL/min flow rate. Column temperature, auto back pressure regulator pressure (ABPR), and modifier solvent were optimized for separation efficiency. Under the optimal conditions, the recoveries for all the enantiomers were 81.3%-94.8% with relative standard deviations (RSD) less than 5.0% at 0.1, 1.0 and 2.0 mg/kg levels, respectively. Good coefficients of determination ( R 2 ≥ 0.993 7) were achieved for all the studied enantiomers in the tobacco over the concentration range of 10-250 ng/mL. The limits of detection (LODs) varied from 0.02 mg/kg to 0.04 mg/kg, and the limits of quantification (LOQs) were ≤ 0.13 mg/kg. The results confirm that the proposed method is green, convenient and reliable for the enantioselective determination of the enantiomers of quizalofop-ethyl in tobacco.