Simultaneous determination of stevioside, rebaudioside A and glycyrrhizic acid in foods by HPLC

A method for the simultaneous determination of stevioside (Stev), rebaudioside A (RebA) and glycyrrhizic acid (GA) in foods was developed. These sweeteners were extracted from foods, except for dried fishes and shellfishes, by dialysis against Tris-HCl buffer (pH 9.0). Dried fishes and shellfishes were extracted with Tris-HCl buffer-methanol (2: 8). The extracts were cleaned up with an Oasis MAX cartridge. The cartridge was washed with 0.05 mol/L sodium acetate (pH 4.0)-methanol (19: 1), and the three sweeteners were eluted with 0.1 mol/L phosphoric acid-acetonitrile (I : 1). Stev, RebA and GA in the eluate were chromatographed on a Develosil RPA-QUEOUS-AR-5 (4.6 mm i.d. X 250 mm) column with 0.02 mol/L phosphoric acid-acetonitrile-methanol (90: 55: 5) as a mobile phase and monitored at 210 nm for Stev and RebA, and at 254 nm for GA. The recoveries of Stev, RebA and GA from 8 kinds of foods spiked at the level of 0.1 g/kg were 81.7-101%, 81.5-100% and 78.6-95.0%, respectively. The determination limits were 0.01 g/kg in samples.