Quantitative structure-capillary column gas chromatographic retention time relationships for natural sterols (trimethylsilyl ethers) from olive oil

A study of the relationship between the capillary column gas chromatographic retention times on two different columns (SE-54 and SE-52) for a group of trimethylsilyl ethers derived from 16 natural sterols found in olive oil and an initial set of 60 molecular descriptors was made. Three kinds of molecular descriptors were used: conventional, topological, and quantum-chemical parameters. By using multivariable regression, two empirical functions for each column were obtained, which were selected on the basis of their respective statistical parameters. The first model relates the retention index with the quantum-chemical descriptors and the second with both topological and conventional descriptors. In all cases, the correlation coefficients of the empirical functions were higher than 0.9880, and the mean relative errors range between 2.88 and 3.24%. In any case, both models could be used, although the second model could be more useful and preferable because it has higher R-2 Values and a lower standard error percentage, giving slightly more exact results.