A new capillary electrophoresis-direct chemiluminescence system for the determination of epinephrine and mechanism study

Abstract

Epinephrine can significantly enhance the intensity of chemiluminescence (CL) produced by the reaction between luminol and potassium hexacyanoferrate(III) (K₃[Fe(CN)₆] under alkaline conditions, and the increased CL intensity is proportional to the concentration of epinephrine. Based on this phenomenon, a new, simple and rapid capillary electrophoresis (CE)-direct CL detection method was established for sensitive determination of epinephrine. Optimal separation and detection were obtained with an electrophoretic buffer of 20 mM sodium (pH = 9.00) borate containing 5 × 10⁻⁵ M luminol and a post-column solution of 1 × 10⁻⁴ M K₃[Fe(CN)₆] in 0.5 M NaOH. A limit of detection of 8.3 × 10⁻⁹ M was achieved. The relative standard derivations (RSD) of CL intensity and migration time were 3.5% and 0.8%, respectively. The applicability of the method for analysis of pharmaceutical and biological samples was examined. And the possible mechanism of the enhanced CL intensity was proposed via examining CL and UV-vis spectra.