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Online normal‐phase high‐performance liquid chromatography/Fourier transform ion cyclotron resonance mass spectrometry: Effects of different ionization methods on the characterization of highly complex crude oil mixtures
Author(s) -
Lababidi Sami,
Schrader Wolfgang
Publication year - 2014
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.6907
Subject(s) - chemistry , fourier transform ion cyclotron resonance , mass spectrometry , atmospheric pressure chemical ionization , analytical chemistry (journal) , electrospray ionization , photoionization , ion cyclotron resonance , chromatography , direct electron ionization liquid chromatography–mass spectrometry interface , ionization , high performance liquid chromatography , ion source , chemical ionization , ion , organic chemistry , cyclotron
RATIONALE Characterization of crude oil represents a challenge for researchers due to its complexity. While Fourier transform ion cyclotron resonance mass spectrometry (FT‐ICR MS) is the method of choice for such complex matrices the high number of ions present limits the efficiency of the analysis due to charge competition and space charge effects. One way to solve this problem is the direct coupling of FT‐ICR MS with high‐performance liquid chromatography (HPLC). METHODS Normal‐phase liquid chromatography was applied on a deasphalted crude oil sample by using a polar aminocyano‐bonded stationary phase with n‐hexane and isopropyl alcohol as a mobile phase. The HPLC system was coupled online to a 12 T ultrahigh‐resolution FT‐ICR mass spectrometer. Ion chromatograms were obtained with electrospray ionization (ESI), atmospheric pressure photoionization (APPI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure laser ionization (APLI). RESULTS The chromatographic separation yielded a group separation into two peaks according to the polarity of the components. Each ionization technique was able to uniquely assign components differing in polarity and aromaticity. Additionally, an increase in aromaticity in the course of retention time for nonpolar species in the first peak was observed. Monitoring the ratio between protonated and radical mono‐nitrogen species was achieved. CONCLUSIONS For the analysis of a crude oil sample, online coupling of a normal‐phase HPLC system to an FT‐ICR mass spectrometer was achieved. The results of the different ionization techniques were compared with each other, which enables a detailed characterization of the complex sample. Copyright © 2014 John Wiley & Sons, Ltd.