ION-EXCLUSION CHROMATOGRAPHY OF ETHANOLAMINES ON AN ANION-EXCHANGE RESIN BY ELUTION WITH POLYOLS AND SUGARS

Ion-exclusion chromatography of mono-, di- and triethanolamines of dif ferent basicity (pK(b)) and hydrophobicity was investigated on a polys tyrene-divinylbenzene (PS-DVB)-based strongly basic anion-exchange res in in the OH- form. Conductivity detection and UV detection at 200 nm were used. When water was as an eluent, the ethanoamines were separate d from strong base (NaOH) but the resolution was low and some peaks we re fronted. This is due mainly to adsorption as a side-effect in the i on-exclusion chromatography. To improve the peak shape and the peak re solution, aqueous eluents containing polyols or sugars with 1-8 alcoho lic OH groups (methanol, ethylene glycol, glycerol, erythritol, xylito l, fructose, sorbitol and sucrose) were tested for the ion-exclusion c hromatographic separation of ethanolamines. When aqueous eluents conta ining polygols or sugars were used, peak fronting was decreased drasti cally by increasing a number of OH groups in the polyols and sugars. T his is due mainly to the increase in the hydrophilicity of the PS-DVB surface by the OH groups. When an aqueous fructose eluent was used, fr uctose was strongly adsorbed on the resin surface. By this permanent c oating method, the ion-exclusion chromatographic separation of ethanol amines was accomplished successfully by elution with water with reason able resolution and highly sensitive UV and conductimetric detection.