REVERSED-PHASE LIQUID-CHROMATOGRAPHY MASS-SPECTROMETRY OF THE UNCOMMON TRIACYLGLYCEROL STRUCTURES GENERATED BY RANDOMIZATION OF BUTTEROIL

The test triacylglycerols were prepared by randomization of natural butterfat followed by silver ion TLC segregation of the saturates, monoenes and dienes. The molecular species were identified by on-line positive chemical ionization mass spectrometry. Within a series of isologous triacylglycerols, those containing the shortest fatty acid chain were eluted last from a reversed-phase column (XX10 > XX8 > XX6 > XX4, where X = long-chain acid), although common experience would have predicted that the shorter and more polar species would be eluted first. A comparable order of elution was obtained for isologous triacylglycerols containing two short- and one long-chain (X88 > X86 > X66 > X84 > X64 > X44) or three short-chain fatty acids per molecule, when compared to triacylglycerols containing medium or long-chain fatty acids in combination with short-chain acids. Since this resolution is similar to that achieved on adsorption chromatography, it is suggested that the C-18 reversed-phase column possesses residual adsorptive activity. No discernible separation was seen among the corresponding positional or reverse isomers of short-chain triacylglycerols with the present reversed-phase system.