Determination of gamma-hydroxybutyric acid in clinical samples using capillary electrophoresis with contactless conductivity detection

A method for the determination of gamma-hydroxybutyric acid (GHB) in urine and serum samples with capillary electrophoresis using capacitively coupled contactless conductivity detection (CE-C(4)D) was developed. The optimized separation buffer consisting of 20 mM of arginine, 10 mM of maleic acid and 30 microM of cetyltrimethylammonium bromide (CTAB) contained 5 mM vancomycin to facilitate the separation of gamma-hydroxybutyric acid from beta-hydroxybutyric acid (BHB), which is also present in clinical samples. The detection limits in the clinical samples were found to be about 2 microg/ml, which is well below the required sensitivity for the recognition of overdosage and adequate for the determination of endogenous concentrations in urine. The determination of GHB in both types of samples was carried out directly after a fourfold dilution without requiring any derivatization or extraction procedures.