DERIVATIZATION OF AMINO-ACIDS IN A MOVING ZONE OF O-PHTHALALDEHYDE INTHE MIDDLE OF A CAPILLARY FOR AMINO-ACID-ANALYSIS BY CAPILLARY ELECTROPHORESIS

Problems in in-situ derivatization in a narrow zone in the middle of a capillary was investigated using a model system composed of amino aci ds and o-phthalaldehyde (OPA). Hydrostatic introduction of a solution of amino acid(s),the running buffer and the OPA solution for specified periods of time in this order from the anodic end of a capillary, fol lowed by application of an appropriate voltage between both ends, resu lted in formation of the OPA derivatives of amino acids, which were im mediately separated by zone electrophoresis while moving through the r est of the capillary and detected at the detector window. Peak intensi ty was varied among amino acids, clue to the variation of zone-overlap ping period, accordingly reaction time. This technique of in-capillary derivatization was liable to be affected by various factors, includin g sample/reagent introduction times and applied voltage, giving rather lower reproducibility of determination than the derivatization at the inlet. However, it was useful for kinetic studies of such rapid react ions as those adopted in this work as a model system. (C) 1998 Elsevie r Science B.V.