Extraction and on-line concentration of flavonoids in Brassica oleracea by capillary electrophoresis using large volume sample stacking
Document Type
Journal Article
Keywords
Broccoli, Capillary zone electrophoresis, Flavonoids, Large volume sample stackingAcid hydrolysis, Analytes, Bioactive compounds, Brassica oleracea, Broccoli, Capillary zone electrophoresis, Cardio-vascular disease, Detection limits, Fresh weight, HPLC analysis, Internal diameters, Kaempferol, Large volume sample stacking, Linear relationships, Migration time, Peak area, Relative standard deviations, Separation voltage, Sodium borate, Total length, Variable concentration, Capillary electrophoresis, Diseases, Fatty acids, High performance liquid chromatography, Phenols, Plants (botany), Separation, Sodium, Flavonoids, borate sodium, brassica oleracea extract, caffeic acid, ferulic acid, flavonoid, kaempferol, para coumaric acid, plant extract, quercetin, sinapic acid, unclassified drug, analytic method, article, Brassica oleracea, capillary zone electrophoresis, high performance liquid chromatography, hydrolysis, large volume sample stacking, online analysis, process optimization, validity, Brassica oleracea, Brassica oleracea var. italica
Faculty
Faculty of Computing, Health and Science
School
School of Natural Sciences
RAS ID
15191
Abstract
Flavonoids are bioactive compounds found in plants. Studies indicate consumption of food containing these compounds may reduce the incidences of cancer and cardiovascular diseases. In broccoli, the flavonoids are present at variable concentrations and so far have mainly been determined using high performance liquid chromatography (HPLC). This paper describes a rapid capillary electrophoresis method, involving large volume sample stacking (LVSS), suitable for the analysis of flavonoids in broccoli. Following acid hydrolysis, the two key flavonoids (kaempferol and quercetin) in a broccoli extract were concentrated on-line by LVSS prior to separation by capillary zone electrophoresis (CZE). Using an optimised method, the extract was injected for 50 s into a 50 μm (internal diameter) × 85 cm (total length) capillary followed by stacking/matrix removal at -5 kV for 83 s. The two analytes were then separated in less than 8 min by CZE using a 10 mM sodium borate buffer (pH 8.40) and a separation voltage of +30 kV at 30 °C. A linear relationship in the range 1-20 ppm was observed for the method (r 2 = 0.9991-0.9995) with detection limits of 0.9 and 0.6 mg/kg of broccoli for kaempferol and quercetin, respectively. This method demonstrated good repeatability for the standard and extract with relative standard deviations of less than 5% for both peak area and migration time measured over five different days (n = 5). The method was successfully applied to quantitatively determine kaempferol and quercetin contents in a commercial broccoli sample as 11.8 and 14.6 mg/kg fresh weight, respectively. This result was validated by HPLC analysis and is within the ranges reported in the literature.
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Comments
Lee, I. S., Boyce, M. C., & Breadmore, M. (2012). Extraction and on-line concentration of flavonoids in Brassica oleracea by capillary electrophoresis using large volume sample stacking. Food Chemistry, 133(1), 205-211.