The renaissance of high-energy CID for structural elucidation of complex lipids: MALDI-TOF/RTOF-MS of alkali cationized triacylglycerols

摘要: Triacylglycerols were analyzed as cationized species (Li+, Na+, K+) by high-energy CID at 20 keV collisions utilizing MALDI-TOF/RTOF mass spectrometry. Precursor ions, based on [M+Li]+-adduct ions exhibited incomplete fragmentation in the high and low m/z region whereas [M+K]+-adducts did not show useful fragmentation. Only sodiated precursor yielded product ion spectra with structurally diagnostic across whole range. The of is dominated abundant charge-remote fatty acid substituents. In favorable cases also positions double bonds or hydroxy groups alkyl chains could be determined. A-type represent end products these fragmentations. B- C-type yield composition individual triacylglycerol loss either one neutral sodium carboxylate residue, respectively. Product allowing substituent positional determination present range enabling identification sn-1/sn-3 substituents (E-, F-, G-type ions) sn-2 (J-type ion). These findings demonstrated synthetic triacylglycerols plant oils such cocoa butter, olive oil, castor bean oil. Typical features obtained MS an even distribution over entire a accuracy ±0.1 to 0.2 u. One limitation application this technique mainly insufficient gating after MS1 (gating window 4 u) separated 2