Enantiomeric purity test of R-(+)-alpha lipoic acid by HPLC using immobilized amylose-based chiral stationary phase

초록

Alpha lipoic acid, an antioxidant, is widely used for treatment of various diseases. It is a racemic mixture, with R-(+)-alpha lipoic acid exhibiting greater potency, bioavailability, and effectiveness than those of the S-form. Thus, selective R-(+)-alpha lipoic acid has been recently used in various applications, necessitating the development of a method to test the enantiomeric impurity in R-(+)-alpha lipoic acid. We developed a simple and fast high-performance liquid chromatography method using a new immobilized amylose-based chiral column (Chiralpak IA-3). Design of experiment was applied to accurately predict the effects and interactions among various factors affecting the analytical parameters and to optimize the chromatographic conditions. This optimized method could completely separate the two enantiomer peaks with a resolution > 1.8 within a short running time (9 min). Then, the optimized method was validated according to the guidelines of the International Conference on Harmonization and applied for quantification of S-(-)-alpha lipoic acid in some commercial R-(+)-alpha lipoic acid tromethamine raw material. Our results suggested that the developed method could be used for routine quality control of R-(+)-alpha lipoic acid products.

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