Gas chromatographic separation of R/S-α-hydroxy fatty acid esters Review Article

Gas chromatographic (GC) separations of R/S-α-hydroxy fatty acids (AHFAs) are carried out on several columns, including α-cyclodextrin derivative (CYDEX-B) chiral column. R/S-AHFAs are well separated on achiral columns (BP-1, non-polar phase and Rtx-2330, very polar phase) as diasteriomeric esters of the optically active alcohols, whereas the shorter chain length of the alcohol tends to give lower separation factor (α) on the same column. The longest chain length of alcohol used in this study is 2-octanol and its ester shows the highest α on the Rtx-2330 capillary column. Thus, the four thermodynamically related column constants (a, b, c and d) of for R- and S-AHFAs standard are determined.ln k′=a+bn+cT+dnTwhere k′ is the retention factor, n the equivalent carbon number and T the absolute temperature. This equation is used to estimate the equivalent n, and also subsequently used to identify and determine the configuration of AHFAs in wool wax without using a standard AHFA as a reference.