DETERMINATION OF POLY(ETHYLENE GLYCOL)S BY BOTH NORMAL-PHASE AND REVERSED-PHASE MODES OF HIGH-PERFORMANCE LIQUID

A normal-phase HPLC system using an amino column has been developed to characterise oligomers of poly(ethylene glycol)s (PEGs) of average M- r 400 to 2000 with derivatisation by dinitrobenzoate. Normal-phase HPL C with gradient elution using ternary solvents of hexane, dichlorometh ane and methanol has produced a baseline resolution for oligomers of P EG 400, 600 and 1000, while PEG 1000 and 2000 were analysed by using b inary solvents of acetonitrile and water. Mixtures of PEGs have been d etermined by these HPLC systems. PEG 400 in a textile finish has also been determined with satisfactory recovery. It has been found that the hydroxyl group of solvents in normal-phase HPLC plays an important ro le in resolution and retention of PEG oligomers. Derivatisation effici ency for PEGs by dinitrobenzoyl chloride and quantitative determinatio n of derivatised PEGs by HPLC have been studied. A reversed-phase (RP) mode of HPLC was examined for determination of PEG 400 oligomers. The normal-phase system provided greater resolution for oligomers of PEGs . (C) 1998 Elsevier Science B.V.