SILVER ION HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY OF ESTERS OF ISOMERIC OCTADECENOIC FATTY-ACIDS WITH SHORT-CHAIN MONOUNSATURATED ALCOHOLS

The retention characteristics of a series of positionally isomeric octadecenoic acids, derivatized with allyl, butenyl, pentenyl and hexenyl alcohols, were studied by high-performance liquid chromatography on an ion-exchange column loaded with silver ions. For a given isomer the retention factor, k', increased with the distance of the double bond in the alcohol moiety from the ester group. The general retention patterns of butenyl, pentenyl and hexenyl esters were similar to those of methyl and phenacyl esters of the same series of isomeric fatty acids. Allyl esters differed in that the effect of double bond position in the fatty acid backbone on retention was weak. The results support the earlier suggestion for simultaneous interaction between one silver ion and one double and one electron-donating atom or group, presumed to be oxygen co-ordinating with silver ions through its free electron pairs.