Predicting Specific Retention Volumes From Relative Retention Data
Andreas Daniel Hartkopf · Journal of Chromatographic Science · 1972
Using a semiempirical correlation equation of the form in Vg (n-octane) = A + B In (tN X/tN n-octane) + C in (tN Y/tN n-octane) + D In (tN Z /tN n-octane), where Vg is the specific retention volume and tN is the net retention time of a solute, Rohrschneider could predict the specific retention volume of n-octane on 72 liquid phases with an average error of 14 percent (J. Chromatog. Sei. 8, 105 (1970)). The work reported here improves on Rohrschneider's approach in three ways: use of theoretically more reasonable retention ratios than Rohrschneider used; elimination of obvious errors in the data used to obtain the correlation equations; and consideration of gas-liquid interfacial adsorption as a contributing retention mechanism. The anomalous behavior of two of the liquid phases examined by Rohrschneider is easily explained by consideration of the extent of gas-liquid interfacial adsorption on these liquid phases. The best correlation result obtained is the following—with x = 2,5-dimethyltetrahydrofuran, y = 2-methyltetrahydrofuran, and z = n-decane, the following constants are obtained: A = −0.239, B = −0.873, C = −0.220, and D = 2.733. This equation predicts the specific retention volume of n-octane on 65 liquid phases with an average error of 9 percent and a maximum error of 21 percent.