Peroxyoxalate chemiluminescence detection for capillary electrophoresis using membrane collection

Capillary electrophoresis (CE) is often limited by the need to measure nanoliter-volume, low-concentration analytes with selectivity and specificity. A post-column chemiluminescence (CL) method is described in which the capillary effluent is collected on a membrane which has been coated with a peroxyoxalate CL reagent, bis(2,4,6-trichlorophenyl)oxalate. After the CE run, the CL reaction is initiated on the membrane by applying hydrogen peroxide, a scientific charge-coupled device (CCD) camera images the resultant CL emission, and an electropherogram is reconstructed. This postcolumn detection scheme decouples the separation parameters from detection and allows longer lived CL reagents to be used with fast separations. As the reaction is catalyzed by imidazole, CL intensities and lifetimes resulting from imidazole-and non-imidazole-running buffers are compared. The postcolumn CL method is compared to on-line UV absorbance detection for a mixture of dansylated amino acids, with limits of detection (LODs) of 1.5 mu M (13 fmol) and separation efficiencies of 170,000 plates. The ability to preserve the sample on the membrane allows several selective detection schemes to be employed; the combination of postcolumn chemiluminescence and radionuclide detection from a single electrophoretic separation is demonstrated. (C) 1998 John Wiley & Sons, Inc.