The retention diagrams of n-octane, n-nonane, n-decane, n-butyl acetate, isobutyl acetate, and isoamyl acetate on the polyarylate Ardel D-100, a copolyester of bisphenol A with terephthalic acid and isophthalic acid, were plotted at temperatures between 120 and 260 degrees C by an inverse gas chromatography technique. The glass-transition temperature of the copolymer was determined to be 190 degrees C from the discontinuity of these diagrams. The retention diagrams of benzene, ethyl benzene, n-propyl benzene, isopropyl benzene, and chlorobenzene were also plotted between 200 and 260 degrees C. The specific retention volume, weight fraction activity coefficient, Flory-Huggins polymer-solvent interaction parameter, hard-core polymer-solvent interaction parameter, and effective exchange energy parameter were determined for the studied solvents. The parameters suggest that the studied aromatic hydrocarbons and aliphatic esters are moderately good solvents and chlorobenzene is a very good solvent for this copolyester, but the n-alkanes are very poor solvents. The solubility parameter of this copolymer was determined to be 11.6 (cal/cm(3))(1/2) at room temperature by extrapolation of the values of the solubility parameters from the studied temperatures to 25 degrees C. (c) 2005 Wiley Periodicals, Inc.