Electrogenerated chemiluminescence detection for capillary electrophoresis

Electrogenerated chemiluminescence (ECL) detection based on the reaction of luminol and H₂O₂ has been developed for capillary electrophoresis. The ECL response at carbon fiber and platinum wire microelectrodes has been investigated. Carbon fiber electrodes are observed to be less sensitive than platinum electrodes but provide a more stable response. The ECL response at a carbon fiber electrode is linear over three orders of magnitude for luminol with a linear correlation coefficient of 0.998. Mass detection limits of 92 amol and 260 amol have been obtained for luminol using platinum wire microelectrodes and carbon fiber microelectrodes, respectively. The influence of hydrogen peroxide concentration (in the detection buffer resrvoir) on the luminescence response has been examined and found to be dependent on electrode type. The dependence of the ECL response on the applied voltage at the microelectrode has been studied for both electrode types. Capillary electrophoresis with ECL detection has been used for analysis of amines derivatized with N‐(4‐aminobutyl)‐N‐ethylisoluminol coupled to N, N‐disuccinimidylcarbonate (ABEI‐DSC). Detection limits of 2.0 fmol and 0.96 fmol are obtained for n‐octylamine and n‐propylamine, respectively. In addition, ABEI‐DSC has been used to successfully label the tripeptide Val‐Tyr‐Val, and micellar electrokinetic capillary chromatography has been used with ECL detection for the separation of ABEI‐DSC labeled amines.