Analysis of Geologically Relevant Metal Porphyrins Using Trapped Ion Mobility Spectrometry–Mass Spectrometry and Theoretical Calculations
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- 作者：Paolo Benigni ; Carlos Bravo ; J. Martin E. Quirke ; John D. DeBord ; Alexander M. Mebel ; Francisco Fernandez-Lima
- 刊名：Energy & Fuels
- 出版年：2016
- 出版时间：December 15, 2016
- 年：2016
- 卷：30
- 期：12
- 页码：10341-10347
- 全文大小：493K
- ISSN：1520-5029
文摘
The structural characterization of metal porphyrins has been traditionally challenging as a result of their large structural and compositional diversity. In the present paper, we show the advantages of gas-phase, postionization separations for the fast identification and structural characterization of metal octaethylporphyrins (Me–OEP) from complex mixtures using trapped ion mobility spectrometry (TIMS) coupled to ultrahigh-resolution mass spectrometry (FT-ICR MS). TIMS–FT-ICR MS allows for the separation of Me–OEP (Me = Mn, Ni, Zn, V═O, and Ti═O) within a crude oil sample based on accurate mass and mobility signatures (with a mobility resolving power of RIMS ∼ 150–250). Accurate collision cross sections are reported for Me–OEP in nitrogen as bath gas (CCSN2). Inspection of the Me–OEP mobility spectra showed a single mobility component distribution for Me–OEP (Me = Mn, Ni, and Zn) and a multi-component distribution for the two metal carbonyls, vanadyl (V═O) and titanyl (Ti═O) Me–OEP. Candidate structures were proposed at the DFT/B3LYP/6-31g(d) level for all Me–OEP mobility bands observed. Inspection of the optimized Me–OEP candidate structures shows that manganese, zinc, and free OEP adopt a planar conformation, the nickel-complexed OEP structure adopts a “ruffled” conformation; and the metal oxide OEP adopts a dome conformation, with carbonyl pointing upward, perpendicular to the plane of the structure.