Separation of peptides by strong cation-exchange capillary electrochromatography

Separation of small peptides on ion-exchange capillary electrochromatograph y (IE-CEC) with strong cation-exchange packing (SCX) as stationary phase wa s investigated. It was observed that the number of theoretical plates for s mall peptides varied from 240 000 to 460 000/m, and the relative standard d eviation for t(0) and the migration time of peptides were less than 0.57% a nd 0.27%, respectively for ten consecutive runs. Unusually high column effi ciency has been explained by the capillary electrophoretic stacking and chr omatofocusing phenomena during the injection and separation of positively c harged peptides. The sample buffer concentration had a marked effect on the column efficiency and peak area of the retained peptides. The influences o f the buffer concentration and pH value as well as the applied voltage on t he separation were investigated. It has been shown that the electrostatic i nteraction between the positively charged peptides and the SCX stationary p hase played a very important role in IE-CEC, which provided the different s eparation selectivity from those in the capillary electrophoresis and rever sed-phase liquid chromatography. A fast separation of ten peptides in less than 3.5 min on IE-CEC by adoption of the highly applied voltage was demons trated. (C) 2000 Elsevier Science B.V. All rights reserved.