Liquid chromatography and differential scanning calorimetry studies on thestates of water in hydrophilic polymer gel packings in relation to retention selectivity

The amounts of water which exhibit selectivity to solutes in water-swollen hydrophilic polymer gel packings were determined by a liquid chromatographi c method designed on the basis of the mobile phase electrolyte effects on t he retention of ionic solutes. The estimated amounts of the water in three types of water-swollen hydrophilic polymer gels, a cross-linked dextran, po ly(vinyl alcohol) and polyacrylamide, agree well with the sum of the amount of freezable bound water and that of non-freezing water determined by mean s of differential scanning calorimetry. Retention selectivities of these pa ckings were evaluated based on the plots of logarithmic distribution coeffi cients, In K-D, of various organic compounds obtained on one packing versus those on another with the same mobile phase, water. It was found that the In K-D vs. In K-D plots between two packings of the same polymer matrix wit h different degrees of cross-linking were linear and the slopes of the plot s depended on the fractions of the freezable bound water and the non-freezi ng water in the stationary phase; the water-swollen hydrophilic polymer pac kings which contained a smaller fraction of the freezable bound water exhib ited larger retention selectivities. (C) 1999 Elsevier Science B.V. All rig hts reserved.