PREDICTION OF GAS-CHROMATOGRAPHIC RETENTION INDEXES OF ALKENES FROM THE TOTAL SOLUBILITY PARAMETERS

Gas chromatographic retention indices (I) for a large number of C-5-C-10 alkenes on different stationary phases at various temperatures were correlated with total solubility parameters (delta(T)), molar volumes (V) and the number (N) of carbon atoms in the solute molecules. The correlation is a new three-parameter equation I=aN+b Delta(V delta(T))+c Delta V+d, which is based on the expanded solubility parameter model. Two new parameters, Delta(V delta(T)) and Delta V, are introduced, accounting for the deviations of the V delta(T) and the V values of the solutes from those of n-alkanes which have the same carbon number as the solutes. The empirically introduced constants a, b, c and d depend on the phase characteristics and column temperature. High correlation coefficients and low standard deviations were found in all instances. Especially for isomeric alkenes, the correlation between the I and delta(T) and V values of the solutes, which is I=bV delta(T)+cV+e, is excellent. The above two equations could be used to predict retention indices of alkenes successfully.