Determination of ethyl glucuronide in human serum by hyphenation of capillary isotachophoresis and zone electrophoresis

The determination of ethyl glucuronide (EtG), a marker of recent alcohol consumption, in human serum by hyphenation of capillary ITP (CITP) and CZE is reported. For CITP step, 1 x 10(-2) M hydrochloric acid adjusted with E-aminocaproic acid (EACA) to pH 4.4 was used as the leading electrolyte, and 1 x 10(-2) M nicotinic acid with EACA, pH 4.4, was used as the terminating electrolyte (TE). All electrolytes contained 0.2% hydroxypropylcellulose to suppress electroosmosis. In CITP, EtG was separated from fast serum macrocomponents chloride, phosphate, lactate, and acetate. Zones of microcomponents including EtG that migrated between acetate and nicotinate were forwarded to the second capillary filled with a BGE identical with the TE. Conductivity detection was used in the CITP step. Sensitive detection in the CZE step was performed using indirect spectrophotometric detection at 254 nm. The assay is based on a 1:5 dilution of serum with deionized water and has a concentration LOD for EtG in diluted sample of 9.8 x 10(-9) M. The method was used for the determination of EtG in sera of volunteers consuming alcohol.