SEPARATION OF OCTYLPHENOL POLYETHER ALCOHOLS SURFACTANTS BY CAPILLARYCOLUMN SFC AND HPLC

Separation of nonionic octylphenol polyether alcohols (OPA) by supercr itical fluid chromatography (SFC) and HPLC is described. Using a densi ty programming and a 50-mu m i.d. capillary column, a total of 18 grou p oligomers was separated. The effects of the operating parameters, su ch as temperatures of mobile phase, flame ionization detector (FID) an d injector, on SFC analysis were investigated. The results demonstrate d that the separation efficiency is better when mobile phase temperatu re is above 100 degrees C, which must be due to the higher volatility of the oligomers. The results also demonstrated that the change of FID temperature from 300 degrees C to 420 degrees C has no effect on the total peak response. The study shows that injector cooling is not nece ssary when the analyte is in methanol. The total peak response was low er when the injector temperature was changed from 21 degrees C to 10 d egrees C. A group of polar oligomers was found in OPA in HPLC analysis , not found in SFC. The result indicates that the polar oligomers pres ent in OPA were not soluble in supercritical fluid carbon dioxide and, therefore, not observed in SFC.