Analysis of phospholipid molecular species by liquid chromatography - atmospheric pressure chemical ionisation mass spectrometry of diacylglycerol nicotinates

A method using liquid chromatography - atmospheric pressure chemical ionisa tion mass spectrometry was evaluated for determining the molecular species composition of phospholipids (phosphatidylcholines from soybean. egg yolk a nd bovine liver) after conversion to diacylglycerol nicotinate derivatives. The structures could be deduced from pseudo-molecular ions ([MH-123](+)) a nd three pairs of monoacyl containing fragment ions. All molecular species in mixed peaks were readily identified and many minor components, earlier n ot encountered in the samples under investigation. were identified. Acyl ch ain regioisomers were readily distinguished by the ratio of the [MH RCHCO]( +) ions. Molecular species differing only in the position of the double bon ds in one polyunsaturated acyl chain were separated on the basis of retenti on times. A half quantitative estimation of the molecular species compositi on of complex samples was achieved by a combination of UV detection and, fo r mixed peaks, the areas of [MH-123](+) ions. (C) 2001 Elsevier Science Ire land Ltd. All rights reserved.