PICOMOLAR ANALYSIS OF PROTEINS USING ELECTROPHORETICALLY MEDIATED MICROANALYSIS AND CAPILLARY-ELECTROPHORESIS WITH LASER-INDUCED FLUORESCENCE DETECTION

We report a method for the analysis of picomolar concentration protein s using electrophoretically mediated microanalysis (EMMA) to label pro teins on-column with a fluorogenic reagent, Labeling is followed by ca pillary zone electrophoresis separation and postcolumn detection based on laser-induced fluorescence. The method provides a concentration de tection limit (3 sigma) of 3 x 10(-13) M for conalbumin. The method pr ovides separation efficiency of 300 000 theoretical plates. Protein ex -tract from a human colon adenocarcinoma cell line generated a dozen m ajor components and many minor components in a 12-min separation; the protein extract from 2.5 cells was used for this analysis. When compar ed to UV absorbance detection, the EMMA method provides 7 000 000-fold improvement in detection limit.