Analysis of triacylglycerols with non-aqueous reversed phase liquid chromatography and positive ion electrospray tandem mass spectrometry

A non-aqueous reversed-phase liquid chromatographic method coupled to elect rospray ionisation (ESI) tandem mass spectrometry was developed for the ana lysis of triacylglycerols (TGs). The synthetic TGs studied were separated a ccording to their equivalent carbon number with a gradient of methanol (con taining 0.01% (v/v) formate adjusted to pH 5.3 with ammonia) and chloroform . ESI mass spectra of TGs yielded positive ion current signals for [M + NH4 ](+) and [M + NH4-RCOONH4](+). The mass spectra also showed signals believe d to arise from [M + K](+). Collision-induced dissociation (CID) of the [M + NH4](+) precursor ion yielded [M + NH4 - RCOONH4](+), [RCO + 74](+) and [ RCO](+) product ions as aids for the structural elucidation of the TGs. In addition, [RCO - 18](+) and small amounts of [RCO - 2](+) product ions were also found. The latter ions were observed only for TGs containing unsatura ted fatty acids. CID of ammoniated 1-stearoyl-2-oleoyl-3-linoleoyl-glycerol (18:0/18:1/18:2) indicated that neutral loss of the sn-2 fatty acid was en ergetically less favourable than loss of the fatty acid from the sn-1 or sn -3 position. Copyright (C) 2001 John Wiley & Sons, Ltd.