Determination of proteinogenic amino acids in human plasma by capillary electrophoresis with contactless conductivity detection

Capillary electrophoresis (CE) with contactless conductivity detection (CCD) represents a viable alternative to liquid chromatography in the analysis of amino acids (AA) in human plasma. After optimizing the composition of the back round electrolyte (BGE), and introducing simple plasma pretreatment to remove spurious protein components, the CE/CCD methods allows determination of 18 from 20 proteinogenic AAs, three nonproteinogenic AAs and creatinine in 60 minutes. AAs are separated in their cationic forms in BGE containing 1.7 M acetic acid and 0.1%, hydroxyethylcellulose, pH 2.2. LODs for individual AAs vary in an acceptable range with minimum of 4.3 mu M for Arg and maximum of 42.9 mu M for Cys. Mean concentrations and concentrations ranges for AAs in human plasma samples front 9 healthy individuals are found to agree well with those determined by an LC method in other two laboratories.