A rapid quantitative determination of phenolic acids in Brassica oleracea by capillary zone electrophoresis
Faculty of Computing, Health and Science
School of Natural Sciences
A simple and rapidcapillaryzoneelectrophoresis method to quantitatively determine the phenolicacid contents inbrassica vegetables is described. Phenolic compounds were extracted from broccoli, broccolini, Brussels sprouts, cabbage and cauliflower and the main hydroxycinnamic acids (sinapic, ferulic, p-coumaric and caffeic acids) were isolated by solid phase extraction with C18 cartridges. Using an optimised method, the four analytes were separated in less than 7 min ina 50 μm × 60 cm capillary with a 15 mM borate buffer (pH = 9.13) and a separation voltage of 30 kV at 30 °C. A linear relationship was observed for the method (r = 0.9997–0.9999) with detection limits ranging from 1.1 to 2.3 mg/kg of vegetables for the analytes. This method demonstrated good reproducibility with coefficients of variation of less than 5% for peak area and less than 1% for migration time (n = 7). The method was successfully applied to quantitatively determine the phenolicacid contents ina range ofbrassica vegetables and the results were in good agreement when compared to those from high performance liquid chromatography analysis.