Development of a compact capillary electrophoresis-chemiluminescence system with ultra-fast peroxyoxalate reaction to monitor the hydrolysis of rhodamine 6G

Abstract

A simple and effective capillary electrophoresis-chemiluminescence (CE-CL) detection system was developed based on an ultra-fast bis(2,4,6-trichlorophenyl)oxalate (TCPO) chemiluminescence (CL) reaction (0.6 s duration) that avoided overlapping peaks and peak tailing. Through a series of static injection experiments, this unusually rapid CL reaction was ascribed to the catalytic effect of imidazole in the tetrahydrofuran solvent, which has been rarely utilized in such investigations. A possible mechanism is given to explain the results. Under the optimized conditions, rhodamine 6 G (R6G) and its hydrolysis product (R6G-COOH) could be efficiently separated through electrophoresis in 7 min, with sensitive CL detection in the proposed CE-CL system. In this way, the alkaline hydrolysis of R6G was monitored, followed by estimation of relative rate constants and activation energy. This finding and application should be helpful in further study for the TCPO CL reaction, and revealed an attractive opportunity for simplifying the CE-CL system, such as in a microchip device.