EFFECT OF SODIUM DODECYL-SULFATE IN PROTEIN SAMPLES ON SEPARATION WITH FREE CAPILLARY ZONE ELECTROPHORESIS

The addition of sodium dodecyl sulphate (SDS) to samples of proteins (conalbumin and ovalbumin), but not to the carrier electrolyte (borate, 0.1 mol/l, pH 10) leads to a total loss in resolution of the analytes in free capillary zone electrophoresis, even at SDS concentrations of 0.1% (w/w). Simultaneously, a sharpening effect on the single peak obtained from the two proteins is observed, simulating favourable dispersion properties of the separation system (apparent plate number of 1 500 000). No such effects are found if SDS is added to the carrier electrolyte. It is demonstrated that the effects observed are not caused by binding of SDS onto the proteins but seem to be generated by conductivity gradients present in the system.