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Jaakko Laakia Alexey Adamov Matti Jussila Christian S. Pedersen Alexey A. Sysoev Tapio Kotiaho 《Journal of the American Society for Mass Spectrometry》2010,21(9):1565-1572
This study demonstrates how positive ion atmospheric pressure photoionization-ion mobility spectrometry-mass spectrometry
(APPI-IMS-MS) can be used to produce different ionic forms of an analy te and how these can be separated. When hexane:toluene
(9:1) is used as a solvent, 2,6-di-tert-butylpyridine (2,6-DtBPyr) and 2,6-di-tert-4-methylpyridine (2,6-DtB-4-MPyr) efficiently produce radical cations [M]+ and protonated [M + H]+ molecules, whereas, when the sample solvent is hexane, protonated molecules are mainly formed. Interestingly, radical cations
drift slower in the drift tube than the protonated molecules. It was observed that an oxygen adduct ion, [M + O2]+, which was clearly seen in the mass spectra for hexane:toluene (9:1) solutions, shares the same mobility with radical cations,
[M]+. Therefore, the observed mobility order is most likely explained by oxygen adduct formation, i.e., the radical cation forrning
a heavier adduct. For pyridine and 2-tert-butylpyridine, only protonated molecules could be efficiently formed in the conditions used. For 1- and 2-naphthol it was
observed that in hexane the protonated molecule typically had a higher intensity than the radical cation, whereas in hexane:toluene
(9:1) the radical cation [M]+ typically had a higher intensity than the protonated molecule [M + H]+. Interestingly, the latter drifts slower than the radical cation [M]+, which is the opposite of the drift pattern seen for 2,6-DtBPyr and 2,6-DtB-4-MPyr. 相似文献
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Adamov A Sysoev AA Grigoras K Laakia J Kotiaho T 《European journal of mass spectrometry (Chichester, England)》2011,17(6):593-597
Using a simple ion source set-up, laser desorption/ionization on silicon (DIOS) was demonstrated with the use of a custom-made drift tube ion mobility spectrometer (IMS), mounted on a commercial triple quadrupole mass spectrometer, and with an IMS equipped with a Faraday plate detector. DIOS was tested by mobility measurement of tetrapropylammonium iodide, tetrabutylammonium iodide and tetrapentylammonium iodide, whilst 2,6-di-tert- butylpyridine was used as a standard. The reduced mobilities measured for the test halides are in concordance with previously obtained ion mobility spectrometry-mass spectrometry data. 相似文献
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Jaakko Laakia Christian Schack Pedersen Alexey Adamov Jyrki Viidanoja Alexey Sysoev Tapio Kotiaho 《Rapid communications in mass spectrometry : RCM》2009,23(19):3069-3076
Negative corona discharge atmospheric pressure chemical ionization (APCI) was used to investigate phenols with varying numbers of tert‐butyl groups using ion mobility spectrometry–mass spectrometry (IMS‐MS). The main characteristic ion observed for all the phenolic compounds was the deprotonated molecule [M–H]−. 2‐tert‐Butylphenol showed one main mobility peak in the mass‐selected mobility spectrum of the [M–H]− ion measured under nitrogen atmosphere. When air was used as a nebulizer gas an oxygen addition ion was seen in the mass spectrum and, interestingly, this new species [M–H+O]− had a shorter drift time than the lighter [M–H]− ion. Other phenolic compounds primarily produced two IMS peaks in the mass‐selected mobility spectra measured using the [M–H]− ion. It was also observed that two isomeric compounds, 2,4‐di‐tert‐butylphenol and 2,6‐di‐tert‐butylphenol, could be separated with IMS. In addition, mobilities of various characteristic ions of 2,4,6‐trinitrotoluene were measured, since this compound was previously used as a mobility standard. The possibility of using phenolic compounds as mobility standards is also discussed. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Pedersen CS Lauritsen FR Sysoev A Viitanen AK Mäkelä JM Adamov A Laakia J Mauriala T Kotiaho T 《Journal of the American Society for Mass Spectrometry》2008,19(9):1361-1366
Ionized acetates were used as model compounds to describe gas-phase behavior of oxygen containing compounds with respect to their formation of dimers in ion mobility spectrometry (IMS). The ions were created using corona discharge at atmospheric pressure and separated in a drift tube before analysis of the ions by mass spectrometry. At the ambient operational temperature and pressure used in our instrument, all acetates studied formed dimers. Using a homolog series of n-alkyl-acetates, we found that the collision cross section of a dimer was smaller than that of a monomer with the same reduced mass. Our experiments also showed that the reduced mobility of acetate dimers with different functional groups increased in the order n-alkyl = branched chain alkyl = cyclo alkyl < aromat. For mixed n-alkyl dimers we found that the reduced mobility of acetate dimers having the same number of carbons, for example a dimer of acetyl acetate and hexyl acetate has the same reduced mobility as a dimer composed of two butyl acetates. The fundamental behavior of acetate monomers and dimers described in this paper will assist in a better understanding of the influence of dimer formation in ion mobility spectrometry. 相似文献
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