Simultaneous Determination of D-iso-Ascorbic Acid, L-Ascorbic Acid and Thiourea Dioxide in Food Additives by Hydrophilic Interaction Chromatography

The food additive sample was dissolved with 100 mmol·L^-1 ammonium formate solutioncontaining 1% (φ, the same below) formic acid. After dilution with acetonitrile, the sample solution was filtered with 0.22 μm millipore membrane. Hydrophilic interaction chromatography was applied to the simultaneous determination of D-iso-ascorbic acid, L-ascorbic acid and thiourea dioxide in the filtrate. InfinityLab Poroshell 120 HILIC-Z chromatographic column (3.0 mm×100 mm, 2.7μm) was used as stationary phase, and a mixture of 100 mmol·L^-1 ammonium formate solution (containing 1% formic acid)and acetonitrile (15+85) was used as mobile phase. Diode array detector was used for determination. Linear relationships between values of peak area and mass concentration of D-iso-ascorbic acid, L-ascorbic acid and thiourea dioxide were kept in the same range of 1.0-100 mg·L^-1, with the same detection limit (3S/N) of 1.0%. On the base of blank sample, test for recovery was made by standard addition method; values of recovery found were in the range of 94.7%-108%, with RSDs (n=6) of determined values less than 8.0%.