Separation and Determination of Salidroside, Caffeic Acid and Gallic Acid in Rhodiola L. by Large-Volume Sample Stacking-Sweeping-Micellar Electrokinetic Chromatography

Abstract

In this study, a new method for simultaneous determination of salidroside, caffeic acid and gallic acid in Rhodiola L. by large volume sample stacking-Sweeping micellar electrokinetic chromatography (LVSS-sweeping-MEKC) has been proposed. The determination conditions containing pH in background solution, concentrations of Na₂B₄O₇, sodium dodecyl sulfate (SDS) and acetonitrile, injection time, negative voltage and separation voltage were optimized. The operating buffer was composed of 20 mmol/L Na₂B₄O₇, 80 mmol/L sodium dodecyl sulfate and 10 % (by volume) acetonitrile at pH 9.7 with a constant temperature of 25 ºC. The UV detection wavelength was 213 nm, the reverse voltage was -8 kV, separation voltage was 20 kV and injection time was 120 s. The linear ranges of the method were 13.1-49.6 μg/L for salidroside, 1.0-15.7 μg/L for caffeic acid and 1.1-18.2 μg/L for gallic acid. The recoveries were 95-106, 98-112 and 91-108 %, respectively. The RSDs of peak area were less than 4 % and detection limits (S/N = 3) were 194, 28 and 29 μg/L for salidroside, caffeic acid and gallic acid respectively.