Lipidomic study of olive fruit and oil using TiO₂ nanoparticle based matrix solid-phase dispersion and MALDI-TOF/MS

A matrix solid-phase dispersion (MSPD) procedure, using titanium dioxide (TiO₂) nanoparticle (NP) as sorbent, combined with a matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS) method was developed for selective extraction, fast visualization and qualitative analysis of phospholipids from olive fruit and oil samples. The protocol was optimized by testing different sorbents and washing and eluting solvents. The results indicated that clean MS spectrum could be obtained when TiO₂ NP was utilized as MSPD sorbent, acidified water (pH5) was used for washing the matrix and enhancing the binding ability, and chloroform and methanol (1/2, v/v) were selected as eluting solvent. In addition, the efficiency of this method was compared with that of the classic Bligh & Dyer method which produced high abundance peaks of glycerides and suppressed the signals of phospholipids. Based on the optimum conditions, olive fruit and oil samples were successfully analyzed in both positive and negative ion modes. The whole method demonstrated to be promising for selective separation of phospholipids from non-phospholipids, and has great potential in fast lipidomic fingerprinting of olive fruits and oils for quality control. © 2013 Elsevier Ltd.