Simultaneous determination of free and conjugated bile acids in serum by cyclodextrin-modified micellar electrokinetic chromatography

A simultaneous determination of 15 free and most conjugated forms of bile acids (BA) in serum using capillary electrophoresis is described. The optimized and validated method proposed in this work is straightforward and rapid, employing affordable equipment. A background electrolyte of 5 mM β-cyclodextrin, 5 mM 2-hydroxypropyl-β-cyclodextrin, 50 mM SDS and sodium borate–dihydrogen phosphate pH 7.0 with 10% of acetonitrile was used. The complete separation of 15 BA, not easily achievable with other methods, is performed in less than 12 min using a UV detector with good precision and accuracy. BA were extracted from pretreated serum samples using a C18-solid-phase extraction and the recovery values ranged from 65 to 107.8%. Limits of quantitation were between 0.58 and 3.2 μM. This method proved to be suitable to determine individual BA profiles which are more useful than total serum bile acids as indicators of metabolic disorders and hepatobiliary diseases.