Comparison of high-performance liquid chromatography and capillary electrophoresis methods for quantitative determination of glycyrrhizinic acid in pharmaceutical preparations.

A high-performance liquid chromatographic (HPLC) and a capillary electrophoretic (CE) method have been developed for the determination of glycyrrhizinic acid in pharmaceuticals. The two methods have been validated and have been compared with respect to their suitability for the said purpose as well as in relation to requirements from the legal authorities. The HPLC method provide a repeatability of the quantitative analysis of glycyrrhizinic acid below 1% relative standard deviation (RSD) which makes the method suitable when the legal authorities requires the content to be within +/-5% of the declaration. The repeatability of the CE method is in the order of 3-5% RSD when using internal standardization. However, using internal standardization as well as peak normalisation (peak area/migration time) indicate that the RSD may be reduced to about 1%. The CE method is suitable as a stability indication method as the degradation product glycyrrhetinic acid can be determined simultaneously.