High Accuracy Mass Measurement Approach in the Identification of Phospholipids in Lipid Extracts: 7 T Fourier-transform Mass Spectrometry and MS/MS Validation

Abstract

Graduate School of Analytical Science and Technology, Chungnam National University, Daejeon 305-764, KoreaReceived September 29, 2010, Accepted February 1, 2011In the present study, the approach of high accuracy mass measurements for phospholipid identifications wasevaluated using a 7 T ESI-FTMS/linear ion trap MS/MS. Experiments were carried out for porcine brain,bovine liver, and soybean total lipid extracts in both positive and negative ion modes. In total, 59, 55, and 18phospholipid species were characterized in the positive ion mode for porcine brain, bovine liver, and soybeanlipid extracts, respectively. Assigned lipid classes were PC, PE, PEt, PS, and SM. In the negative ion mode,PG, PS, PA, PE, and PI classes were observed. In the negative ion mode, for porcine brain, bovine liver, andsoybean lipid extracts, 28, 34, and 29 species were characterized, respectively. Comparison of our results withthose obtained by other groups using derivatization-LC-APCI MS and nano-RP-LC-MS/MS showed that ourapproach can characterize PC species as effectively as those methods could. In conclusion, we demonstratedthat high accuracy mass measurements of total lipid extracts using a high resolution FTMS, particularly, 7TFTMS, plus ion-trap MS/MS are very useful in profiling lipid compositions in biological samples. Abbreviation: PA, phosphatidic acid; PC, phosphatidylcholine; PE, phosphatidylethanolamine; PEt, phosphatid-ylethanol; PG, phosphatidylglycerol; PI, phosphatidylinositol; PS, phosphtidylserine; SM, sphingomyelinKey Words : Lipids, Fourier transform ion cyclotron resonance mass spectrometer, Linear ion trap, Accuratemass measurements, Lipid databaseIntroductionFourier transform-ion cyclotron resonance mass spectro-metry (FT-ICR MS or FTMS) offers an ultrahigh massresolution and extraordinary mass accuracy, which has thusled to its wide applications in protein/peptide analysis.