Determination of Lipoic Acid in Biological Samples with Acetonitrile–Salt Stacking Method in CE

Abstract

An acetonitrile–salt stacking method was established for the assay of lipoic acid (LA) in biological samples. Samples were deproteinized with acetonitrile at a final concentration of 60 % (v/v) and then injected hydrodynamically at 3.45 × 103 Pa for 180.0 s. The optimum background electrolyte was found to be 90.0 mmol L−1 pH 9.1 borate buffer. LA could be detected within 35 min at +7.0 kV with satisfactory repeatability (relative standard deviations, RSDs, of migration times and peak areas were both below 10 % for intraday and interday; n = 6/9) and a relatively low limit of detection of ca. 0.5 μmol L−1.