Fast determination and quantification of triacylglycerols in plant oil by direct matrix-assisted laser desorption ionization time-of-flight mass spectrometry(MALDI-TOF-MS)

Triacylglycerols(TGs)are the main constituents(95%-98%)of plant oil with high nutritional value.They are usually determined by high performance liquid chromatography coupled with mass spectrometry(HPLC-MS)which takes a relatively long time during chromatographic separation.Therefore,in this study,a method about fast determination and quantification of TGs in plant oil based on MALDI-TOF-MS(matrix-assisted laser desorption ionization time-of-flight mass spectrometry)was established.OCNT(oxidized carbon nanotube)and CNT(carbon nanotube)were firstly used as matrix of MALDI-TOF-MS for TGs identification.Satisfyingly,OCNT showed good ionization efficiency,especially when used with CHCA(α-Cyano-4-hydroxy cinnamic acid).Sandwich method was optimized to solve the problem that how matrix and sample were deposited to the plate well and to improve ionization efficiency.Nine calibration curves were established for TGs quantification analysis in plant oil.To verify the accuracy of this method,relative content(%)of fatty acids(FAs)calculated from TGs in peanut oil,rapeseed oil,and soybean oil,respectively,by MALDI-TOF-MS were compared with that calculated from FAMEs(fatty acid methyl esters)by gas chromatography.In general,the results were relatively consistent,proving that this method was convenient,fast and accurate for the determination of main TG molecular species in plant oil.