A simple and specific method for estimation of lipoic acid in human plasma by high performance liquid chromatography

A rapid high performance liquid chromatographic method for determination of lipoic acid in human plasma was developed and validated. The method involved extraction of lipoic acid in ethanol consisting of 50 mM disodium hydrogen phosphate: acetonitrile: methanol in the ratio of 50:30:20. The separation was done using a C18 column (150 mm) and detection was carried out using UV detection at 201 nm. The assay was found to be linear in the range of 0.78-50 μg/ml with the correlation coefficient of 0.9998. Intra and inter-day variations were determined by processing each standard concentration in duplicate for five consecutive days. The average recovery of lipoic acid from plasma was 113%. The developed method demonstrates better sensitivity, precision, accuracy, stability and linearity when compared with the methods previously used. The method is simple and can be used for the determination of lipoic acid in basic research studies as well as in standard clinical laboratories