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 spe cificity. 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)oxa late. After the CE run, the CL reaction is initiated on the membrane b y applying hydrogen peroxide, a scientific charge-coupled device (CCD) camera images the resultant CL emission, and an electropherogram is r econstructed. This postcolumn detection scheme decouples the separatio n 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-imidazo le-running buffers are compared. The postcolumn CL method is compared to on-line UV absorbance detection for a mixture of dansylated amino a cids, with limits of detection (LODs) of 1.5 mu M (13 fmol) and separa tion efficiencies of 170,000 plates. The ability to preserve the sampl e on the membrane allows several selective detection schemes to be emp loyed; the combination of postcolumn chemiluminescence and radionuclid e detection from a single electrophoretic separation is demonstrated. (C) 1998 John Wiley & Sons, Inc.