COMPARISON OF NOVEL SAMPLING METHODS FOR THE ANALYSIS OF CAPILLARY ELECTROPHORESIS FRACTIONS BY MATRIX-ASSISTED LASER DESORPTION IONIZATIONTIME-OF-FLIGHT MASS-SPECTROMETRY/

Two methods for the collection of capillary electrophoresis fractions for analysis by matrix-assisted laser desorption/ionization have been investigated; the first using a novel ion-porous Joint design for drop wise fraction collection and the second, a process of electrospray dep osition, Sensitivity shot-to-shot reproducibility, effect of matrix pr eparation and influence of buffer additives encountered in micellar el ectrokinetic capillary chromatography (MECC) have been examined using a standard peptide, methionine enkephalin. The direct collection of dr oplets from the capillary outlet was found to give a superior signal i ntensity, whereas the electrospray method, in its first stage of devel opment, suffered through dilution effects and excessively wide sample distribution. The target compound was successfully collected by electr ospray deposition and results indicated that signal intensity and samp le homogeneity would be enhanced if the sprayed output could be collec ted into the sample wells in its entirety, The advantage of using elec trospray deposition for the preparation of matrix layers followed by d irect droplet collection onto the electrosprayed matrix was clearly de monstrated by improvements in both sensitivity and shot-to-shot varian ce In signal intensity across the sample well compared with collection onto spotted matrix, In addition, compatibility of the droplet collec tion method with MECC was illustrated by the recovery of the compound of interest from a buffer containing 30 mM sodium dodecyl sulphate. (C ) 1997 by John Wiley & Sons, Ltd.