Chemometric evaluation of the band broadening in micellar electrokinetic chromatography of peptides

Very high efficiencies were obtained for enkephalin-related peptides with low distribution to anionic micelles of taurodeoxycholate (TDC), while the efficiencies decreased drastically for peptides with a strong association to the micelles. This phenomenon was evaluated by studying the influence of TDC concentration, injected plug length, applied voltage, temperature, ionic strength of the background electrolyte and composition of injected solution on the band broadening. A chemometric approach, using a fractional factorial design for the screening experiment and response surface modelling was applied to evaluate the effect of the experimental factors on the peak width of the peptides. Partial least square regression of the peak widths at different TDC concentrations revealed two different phenomena in the system. One in which electrophoretic migration in the aqueous phase dominated, giving narrow peak widths, and a second dominated by micellar solubilization, resulting in peak widths four-times broader for the peptides, probably due to slow sorption-desorption kinetics. (C) 1998 Elsevier Science B.V. All rights reserved.