Batch-Type Chemiluminescence Detection Cell for Sensitization and Simplification of Capillary Electrophoresis

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Abstract
A simple and convenient chemiluminescence detection cell was designed for capillary electrophoresis. The detection cell easily combined with capillary electrophoresis equipment. Luminol chemiluminescence was adapted for use with the detection cell. Detailed analysis and testing of the system revealed that luminol could be determined over a range of 2.5 × 10-10−6.5 × 10-7 M (correlation coefficient, 0.999), with a detection limit (S/N = 3) of 2.5 × 10-10 M (7 amol). Furthermore, each component in a mixture of glycine, glycylglycine, and glycylglycylglycine, which were labeled with isoluminol isothiocyanate, was baseline separated and sensitively detected. Moreover, the stacking procedure was applied to postcolumn detection in capillary electrophoresis. When acetonitrile stacking was used under certain conditions in the present system, chemiluminescence intensities of luminol and labeled compounds were about 1 order of magnitude higher than those obtained without stacking. The detection limit for luminol was 1.5 × 10-11 M (S/N = 3), representing the highest sensitivity of luminol yet reported. Finally, the effect of p-iodophenol as an enhancer of luminol chemiluminescence was examined under weak alkaline conditions. The chemiluminescence intensity of luminol was ∼2 orders of magnitude higher than that in the unenhanced reaction. A preliminary immunoassay using horseradish peroxidase-labeled anti-mouse IgG was also developed.