Determination of rutin, chlorogenic acid and quercetin in solidaginis by large volume sample stacking with polarity switching and acid barrage stacking

The sensitivity of capillary electrophoretic separation of rutin, chlorogenic acid and quercetin was enhanced by combination use of large volume sample stacking with polarity switching (LVSSPS) and acid barrage stacking (ABS). Separating conditions, including the background electrolyte pH and concentration, sample injection and acid barrage were optimized. The optimum conditions were: a background electrolyte of 30 mM Na2B2O7 of pH 9.25, hydrodynamic injection of the sample (60s, 5 psi), then applied voltage of -25 kV, and then hydrodynamic injecting of 0.15 mol/L HAc (18 s, 0.5 psi), and at last separation with 25 kV. Under these conditions, the three analytes could be separated with a sample-to-sample time of 14 min and detection limits from 9.0 to 12.5 ng/mL. When compared to a conventional hydrodynamic injection, the sensitivity was enhanced between 333 to 506 times and the method is 3.6-5.3 times more sensitive than LVSSPS. The applicability of the developed method was demonstrated by the detection of the analytes in aqueous extract of solidaginis.