SOLUTE ADSORPTION ON POLYMER-COATED FUSED-SILICA CAPILLARY ELECTROPHORESIS COLUMNS USING SELECTED PROTEIN AND PEPTIDE STANDARDS

Three series of basic proteins and peptides were selected for use in s tudying the adsorption behavior of fused-silica capillary electrophore sis columns. A comparative study of untreated and treated fused-silica columns was done. The polymers used as coating materials ranged from very hydrophobic to very hydrophilic. The average efficiency of weakly hydrophilic Ucon-coated capillaries for basic proteins was over 1 mil lion theoretical plates at a buffer pH of 4.8. For this coating, it wa s found that the maximum column efficiency was obtained at a film thic kness of approximately 100 nm. It was easily seen that both ionic and hydrophobic interaction forces can play important roles in protein ads orption onto the capillary walls. Furthermore, strongly hydrophilic po lymer coatings may possibly lead to hydrogen-bonding interactions, whi ch decrease column efficiency. Studies have been conducted using two s eries of polypeptides with varying chain lengths. One series was used to study the effect of polypeptide chain length on retention behavior. Efficient separations of bioactive peptide drugs on Ucon-coated colum ns were achieved. The results indicate that high efficiency and resolu tion of basic peptides tested can be realized on columns modified with weakly hydrophilic polymers at a pH value of about 5.