Determination of lipoic acid in dietary supplement preparations by capillary electrophoresis.

The present study deals with the development of a method for the quantitative determination of lipoic acid in a dietary supplement preparation. A rapid capillary electrophoretic method is developed using UV detection at 208 nm. Although lipoic acid is only weakly UV-absorbing, at this wavelength it could be detected with sufficient sensitivity with an LOD and LOQ of 0.8 and 2.5 microg/ml, respectively. Analysis time was less than 9 min. The compound was extracted from tablets with a recovery of 98.3% and a precision of 2.8% RSD.