DETERMINATION OF PEG CONCENTRATION IN ITS AQUEOUS-SOLUTION USING DIFFERENTIAL SCANNING CALORIMETRY

The Freezing and melting behavior of aqueous poly (ethylene glycol) (PEG) solutions up to a concentration of 10% was examined using DSC. So long as the molecular weight of PEG is over 1000, the cooling and heating DSC curves have two peaks, which are attributed to freezable bound water and free water. The amounts of freezable bound water and non-freezing water linearly increase with an increase of PEG concentration. Therefore, a method using DSC was proposed for determining the concentration of aqueous PEG solutions. Although PEG concentration can be determined by the heat of freezable bound water, the ratio of heat of freezable bound water to heat of free water is a better way to determine the concentration. (C) 1993 John Wiley & Sons, Inc.