ABSTRACT
Abstract A chiral separation and residue determination method for cis-epoxiconazole enantiomers in apple, grape and tea samples was developed and validated by ultra performance convergence chromatography combined with quadrupole time-of-flight mass spectrometry ( UPC2-QTOF/MS) . The Chrial CCA column was used to separate cis-epoxiconazole enantiomers and the chromatography conditions ( mobile phase modifier and proportion, column temperature, automated backpressure regulator, and auxiliary solvent ) were optimized. Samples were extracted by acetonitrile, and respectively purified by Cleanert TPT or Pesti-Carb solid phase extraction ( SPE ) columns, then analyzed by UPC2-QTOF/MS. The optimum conditions were as follows:mobile phase was CO2/isopropanol (95: 5, V/V), flow-rate was 2. 0 mL/min, automated backpressure regulator (ABPR) was 13. 79 MPa, column temperature was 30℃, with a post-column mauxiliary solvent of methanol/water (1:1, V/V) containing 2 mmol/L ammonium formate. The analyte was quantified by matrix external standard method. The results showed that linear range of this method was 0. 01-1. 00 mg/L, and the correlation coefficients were above 0 . 99 . The recoveries of cis-epoxiconazole enantiomers at three spiked levels (0. 005, 0. 025 and 0. 25 mg/kg) in fruit matrix were 67. 9%-92. 8% with relative standard deviations (RSDs, n=6) less than 10%, and the limit of quantification (LOQ) of enantiomers was 0. 005 mg/kg. The recoveries of cis-epoxiconazole enantiomers at three spiked levels (0. 01, 0. 05 and 0. 5 mg/kg) in black tea were 74 . 1% -84 . 0% with RSDs ( n=6 ) less than 8%, and the LOQ for these two enantiomers was 0. 01 mg/kg. This method is rapid, convenient and reliable, and could meet the requirement of residue analysis.