Development of intelligent monopolar electrode mass spectrometry based method for lipidomics study of tuna viscera

iKnife MS is a kind of rapid evaporative ionization mass spectrometry (REIMS) without sample pre-preparation. In this study, an method was established for the real-time lipidomics profiling of the viscera of tuna to further investigate its nutritional value. The tissue was cut directly by iKnife, the aerosol containing phospholipid ions was generated and transferred into the mass spectrometer via a special REIMS interface. The parameters of iKnife were optimized to increase the signal-to-noise ratios of phospholipids and the stability of phospholipid signals. The results showed that a total of 41 molecular species of phospholipids was found and identified in the m/z range of 699.50 and 911.56. The most intensity peak at m/z 790.5 was identified as [PE 40:6-H]^- (10.03%) followed by m/z 745.5 ([PA 40:7-H]^-, 9.02%). The final results indicated that the proposed method was good in selectivity, accuracy, and sensitivity. The results of this study can be a reference for the application of mass spectrometry technologies, and provide a basis for the detection and comprehensive utilization of functional lipids in tuna by-products. (authors)