An exact quantitative structure/gas-chromatographic retention relationship for alkylbenzenes

The QSRR for alkylbenzenes chromatographed on a squalane column is studied for a general model describing the chromatographic retention. The vapour-pressure index, I_p, proposed by Bonastre and Grenier, is chosen as the basic contribution; more than 25 topological, structural, geometrical and electronic indices of the solute were tested for tuning the calculated value of the retention index, I_calc. The routinely attainable interlaboratory reproducibility for the experimental indices, I_exp., of alkylbenzenes is taken as ±3 units, and a four-parameter equation is derived which adequately describes the retention of thirty C₆–C₁₁ alkylbenzenes on squalane. The correlation coefficient is 0.99990, the variance of the calculated indices around the experimental values (taken as the unified retention index, UI_T) is 1.73 and the maximum difference between the I_calc. and UI_T is 2.8 units.