Large Volume Sample Stacking (LVSS) in Capillary Electrophoresis (CE) with Response Surface Methodology (RSM) for the Determination of Phenolics in Food Samples

Abstract

Abstract A capillary electrophoresis method with large volume sample stacking (CE-LVSS) has been developed and validated for the simultaneous determination of seven phenolic compounds: naringin, rutin, carnosic acid, apigenin, quercetin, morin, and chichoric acid. Optimization was carried out by response surface methodology and a set of 20 experiments helped to optimize the parameters such as the concentration of buffer, buffer pH, and applied voltage. Analytes were separated using a 50\u2009µm diameter capillary with 56\u2009cm effective length and an extended light path using 20\u2009mM borate buffer at pH 9.2. The LVSS method was optimized and a three- to fivefold improvement in detectability was achieved with injection at 100 mbar for 20\u2009s followed by polarity switching at –20\u2009kV for 6\u2009s. The linearity values of all seven analytes were observed in the concentration ranges from 0.5 to 50\u2009µg/mL for CE and 0.1 to 25\u2009µg/mL for LVSS. The limits of detection were from 0.012 to 0.241 and 0.003 to 0.086\u2009µg/mL for CE and LVSS. The obtained limits of quantitation were within 0.041 to 0.802 for CE and 0.012 to 0.286\u2009µg/mL for LVSS. The recoveries were between 91.1 and 109.8% and 96.3 and 108.4% for CE and LVSS, respectively. The developed method has been successfully applied for the quantitative determination of analyzed components from food samples that are important sources of these compounds.