UV Lamp as a Facile Ozone Source for Structural Analysis of Unsaturated Lipids Via Electrospray Ionization-Mass Spectrometry
- 380 Downloads
Ozonolysis of alkene functional groups is a type of highly specific and effective chemical reaction, which has found increasing applications in structural analysis of unsaturated lipids via coupling with mass spectrometry (MS). In this work, we utilized a low-pressure mercury lamp (6 W) to initiate ozonolysis inside electrospray ionization (ESI) sources. By placing the lamp near a nanoESI emitter that partially transmits 185 nm ultraviolet (UV) emission from the lamp, dissolved dioxygen in the spray solution was converted into ozone, which subsequently cleaved the double bonds within fatty acyls of lipids. Solvent conditions, such as presence of water and acid solution pH, were found to be critical in optimizing ozonolysis yields. Fast (on seconds time scale) and efficient (50%–100% yield) ozonolysis was achieved for model unsaturated phospholipids and fatty acids with UV lamp-induced ozonolysis incorporated on a static and an infusion nanoESI source. The method was able to differentiate double bond location isomers and identify the geometry of the double bond based on yield. The analytical utility of UV lamp-induced ozonolysis was further demonstrated by implementation on a liquid chromatography (LC)-MS platform. Ozonolysis was effected in a flow microreactor that was made from ozone permeable tubing, so that ambient ozone produced by the lamp irradiation could diffuse into the reactor and induce online ozonolysis post-LC separation and before ESI-MS.
KeywordsOzonolysis Unsaturated lipid Electrospray ionization Lipidomics LC-ms
Financial support from NSF CHE-1308114 and NIH R01-GM118184 is greatly appreciated. C.A.S. acknowledges the Purdue Department of Chemistry for the Emerson Kampen Fellowship Award.
- 3.Niki, E.: Biomarkers of lipid peroxidation in clinical material. Biochim. Biophys.Acta Gen. Subj. 1840, 809–817 (2014)Google Scholar
- 24.Bowman, A.P., Abzalimov, R.R., Shvartsburg, A.A.: Broad separation of isomeric lipids by high-resolution differential ion mobility spectrometry with tandem mass spectrometry. J. Am. Soc. Mass Spectrom. 28, 1552–1561 (2017)Google Scholar
- 26.Castroperez, J., Roddy, T.P., Nibbering, N.M., Shah, V., Mclaren, D.G., Previs, S., Attygalle, A.B., Herath, K., Chen, Z., Wang, S.P.: Localization of fatty acyl and double bond positions in phosphatidylcholines using a dual stage CID fragmentation coupled with ion mobility mass spectrometry. J. Am. Soc. Mass Spectrom. 22, 1552–1567 (2011)CrossRefGoogle Scholar
- 30.Harrison, K.A., Davies, S.S., Marathe, G.K., McIntyre, T., Prescott, S., Reddy, K.M., Falck, J.R., Murphy, R.C.: Analysis of oxidized glycerophosphocholine lipids using electrospray ionization mass spectrometry and microderivatization techniques. J. Mass Spectrom. 35, 224–236 (2000)CrossRefGoogle Scholar
- 47.Grimm, R.L., Hodyss, R., Beauchamp, J.L.: Probing interfacial chemistry of single droplets with field-induced droplet ionization mass spectrometry: physical adsorption of polycyclic aromatic hydrocarbons and ozonolysis of oleic acid and related compounds. Anal. Chem. 78, 3800–3806 (2006)CrossRefGoogle Scholar
- 53.Pham, H.T., Maccarone, A.T., Campbell, J.L., Mitchell, T.W., Blanksby, S.J., Maccarone, A.T.: Ozone-induced dissociation of conjugated lipids reveals significant reaction rate enhancements and characterisctic odd-electron product ions. J. Am. Soc. Mass Spectrom. 24, 289–296 (2013)Google Scholar