CHEMOMETRIC EVALUATION OF THE BAND BROADENING IN MICELLAR ELECTROKINETIC CHROMATOGRAPHY OF PEPTIDES

Very high efficiencies were obtained for enkephalin-related peptides w ith low distribution to anionic micelles of taurodeoxycholate (TDC), w hile the efficiencies decreased drastically for peptides with a strong association to the micelles. This phenomenon was evaluated by studyin g the influence of TDC concentration, injected plug length, applied vo ltage, temperature, ionic strength of the background electrolyte and c omposition of injected solution on the band broadening. A chemometric approach, using a fractional factorial design for the screening experi ment and response surface modelling was applied to evaluate the effect of the experimental factors on the peak width of the peptides. Partia l least square regression of the peak widths at different TDC concentr ations revealed two different phenomena in the system. One in which el ectrophoretic migration in the aqueous phase dominated, giving narrow peak widths, and a second dominated by micellar solubilization, result ing in peak widths four-times broader for the peptides, probably due t o slow sorption-desorption kinetics. (C) 1998 Elsevier Science B.V. Al l rights reserved.