Gas chromatographic differentiation of 4-desmethyl-, 4-monomethyl- and 4,4-dimethyl-sterols. Part II : differentiation of sterols based on deltaRAc-values on four stationary phases.

The deltaRAc-values, i.e., ratios of retention data for sterol acetates to those for the corresponding free sterols, were determined for fourteen 4-desmethylsterols, seven 4-monomethylsterols and twenty-two 4,4-dimethylsterols on SE-30, OV-17, QF-1 and HiEFF-8B stationary phases. The QF-1 phase is found sperior to the others in affording the values which are the most effective for differentiation between the three sterol groups. Within the same sterol group, the values for individual sterol members on any of the stationary phases differ to some extent due to minor variations in their skeletal structure. These differences are useful for distinguishing individual members of the same sterol group differing in their skeletal structure, particularly in the position of double bond. The relative deltaRAc-values, i.e., ratios of deltaRAc-values of individual sterols to the deltaRAc-value of a standard sterol, are found almost independent upon the operating conditions of gas liquid chromatography and may be regarded as a characteristic value of sterols on one and the same stationary phase.