DYNAMIC CONTROL AND INDIRECT ABSORPTION DETECTION FOR HIGH-SPEED CAPILLARY ELECTROPHORETIC SEPARATION OF ORGANIC-ACIDS

Dynamic control and indirect absorption detection have been combined f or the separation of eight small aliphatic organic acids in less than 4 min. Electroosmotic flow (EOF) coefficients in 5 mM 8-hydroxyquinoli ne-5-sulfonic acid (8-HQSA) (pH 3.00) and 3 mM 1,2,4,5-benzenetetracar boxylic acid (BTA) solutions are 4.35 and 1.65.10(-4) cm(2)/V s, respe ctively, In the BTA system, relatively large amounts of sodium ions ad sorbed into the capillary wall are the most probable reason for the sm all EOF, in turn causing problems for the separation of all acids. In contrast to BTA, 8-HQSA could be used for the separation of all eight organic acids. Limits of detection of analytes are at the level of sev eral tens of mu M at pH 3.00 in the 8-HQSA system. This new technique provides several features such as high speed, reasonable resolution an d sensitivity, and ease of operation. (C) 1998 Elsevier Science B.V.