Liquid chromatography with particle-beam electron-impact mass spectrometry of diacylglycerol nicotinates.

Several synthetic diacylglycerols and natural mixtures derived from soybean, egg yolk, and bovine liver phosphatidylcholines were examined in the form of nicotinate derivatives by liquid chromatography with particle-beam electron-impact mass spectrometry. High-performance liquid chromatography was carried out in the reversed-phase mode with a base-deactivated octyl-/octadecylsilyl stationary phase. The nature (size and degree of unsaturation) of the acyl residues was readily determined from the mass spectra. Uniquely, the positions of the double bonds could be deduced, although this became increasingly difficult as the degree of unsaturation of diacylglycerols containing mixed acyl residues increased. Reverse 1,2-diacylglycerol isomers could be distinguished by their mass spectra.