INDIRECT ULTRAVIOLET DETECTION OF BIOLOGICALLY RELEVANT ORGANIC-ACIDSBY CAPILLARY ELECTROPHORESIS

Indirect UV detection of fourteen short-chain organic acids (e.g., oxa lic acid, citric acid, malonic acid, tartaric acid, methylmalonic acid , alpha-ketoglutaric acid, succinic acid, ethylmalonic acid, methylsuo cinic acid, glutaric acid, apidic acid, methylglutaric acid, lactic ac id and pyruvic acid) by capillary electrophoresis is described. The me thod used phthalate as the UV-absorbing additive in carbonate buffer a nd the non-absorbing analytes were detected indirectly at 230 nm. The influences of buffer pH, ionic strength, concentration of phthalate an d organic modifier on indirect signal response and migration behavior of the organic acids were investigated. Comparisons of reproducibility on migration time, limit of detection and separation efficiency among three types of capillary (e.g., polyacrylamide-coated, myristyltrimet hylammonium bromide-coated and uncoated capillaries) were conducted. T he method developed was applied to detect succinic acid, methylmalonic acid, citric acid, glutaric acid and lactic acid in human body fluids , and preliminary results were provided.