Abstract: A method for the simultaneous determination of twenty-three phenolic acids in cauliflower (Brassica oleracea L. var. botrytis L.) and broccoli (B. oleracea L. var. italica) was developed by ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The target analytes were separated on an Acquity UPLC HSS T3 column (2.1 mm × 150 mm, 1.8 μm) under a gradient elution mode using a mobile phase consisting of 0.1% formic acid and 0.1% formic acid acetonitrile. The flow rate was 0.3 mL/min and the column temperature was 45 ℃. The target compounds were analyzed in the negative ion multiple reaction monitoring (MRM) mode. Good linear relationships were obtained for all the analytes in the concentration range of 1.0–500.0 μg/L were obtained with high correlation coefficients over 0.992. The precision, repeatability and stability, expressed as relative standard deviation (RSD), were lower than 5.10%. The recoveries from spiked samples ranged from 81.32% to 100.39%, with RSD below 6.21%. The proposed method was applied to the determination of phenolic compounds in broccoli and cauliflower samples collected from five different cities. The method showed time saving, high sensitivity, and good repeatability, and was suitable for the simultaneous determination of phenolic compounds in cauliflower, broccoli and other vegetables.

Key words: UPLC-MS/MS, phenolic acids, cauliflower (Brassica oleracea L. var. botrytis L.), broccoli (B. oleracea L. var. italica)