Electron-Capture Mass Spectrometry: A Powerful Tool in Biomedical Trace Level Analysis

Leis, Hans Jörg; Fauler, Günter; Rechberger, Gerald; Windischhofer, Werner

doi:10.2174/0929867043365035

Cited by 18 publications

(14 citation statements)

References 107 publications

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“…However GC-MS has been more extensively used for the determination of protein adducts, which act as surrogate markers of exposure to carcinogens (42,73,74). Numerous DNA adducts have been studied using gas chromatographyelectron capture negative chemical ionization mass spectrometry (GC-EC-NCI-MS) and comprehensive reviews on electron capture MS have been published by Giese (2000) as well as Leis et al (2004) (75,76). DNA base adducts which have been studied using this technique include malondialdehyde-guanine, N-7 (2-hydroxyethyl)guanine (N-7(2-OHEt)G), N 2 ,N-3 ethenoguanine, N-1,N 2 ethenoguanine and N-1, N 6 ethenoadenine (77-80).…”

Section: Mass Spectrometry In the Analysis Of Dna Adductsmentioning

confidence: 99%

Liquid chromatography-electrospray ionization-mass spectrometry: the future of DNA adduct detection

2005

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Section: Mass Spectrometry In the Analysis Of Dna Adductsmentioning

confidence: 99%

Liquid chromatography-electrospray ionization-mass spectrometry: the future of DNA adduct detection

2005

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“…Traditionally, gas chromatography electron capture-negative ion chemical ionization-mass spectrometry (GC/EC-NICI-MS) has been one of the most sensitive and specific analytical methods, and has been widely used in the analysis of natural electrophores and other compounds after electrophoric derivatization [6]. Recently, LC/EC-APCI-MS methodology [7] was developed and used to analyze some low polarity compounds.…”

mentioning

confidence: 99%

Negative ion-atmospheric pressure photoionization: Electron capture, dissociative electron capture, proton transfer, and anion attachment

Song

Wellman

Yao

et al. 2007

J. Am. Soc. Mass Spectrom.

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To better guide the development of liquid chromatography/electron capture-atmospheric pressure photoionization-mass spectrometry (LC/EC-APPI-MS) in analysis of low polarity compounds, the ionization mechanism of 19 compounds was studied using dopant assisted negative ion-APPI. Four ionization mechanisms, i.e., EC, dissociative EC, proton transfer, and anion attachment, were identified as being responsible for the ionization of the studied compounds. The mechanisms were found to sometimes compete with each other, resulting in multiple ionization products from the same molecule. However, dissociative EC and proton transfer could also combine to generate the same [M Ϫ H] Ϫ ions. Experimental evidence suggests that O 2 Ϫ· , which was directly observed in the APPI source, plays a key role in the formation of [M Ϫ H] Ϫ ions by way of proton transfer. Introduction of anions more basic than O 2 Ϫ· , i.e., C 6 H 5 CH 2 Ϫ , into the APPI source, via addition of di-tert-butyl peroxide in the solvent and/or dopant, i.e., toluene, enhanced the deprotonation ability of negative ion-APPI. Although the use of halogenated solvents could hinder efficient EC, dissociative EC, and proton transfer of negative ion-APPI due to their EC ability, the subsequently generated halide anions promoted halide attachment to compounds that otherwise could not be efficiently ionized. With the four available ionization mechanisms, it becomes obvious that negative ion-APPI is capable of ionizing a wider range of compounds than negative ion chemical ionization (NICI), negative ion-atmospheric pressure chemical ionization (negative ion-APCI) or negative ion-electrospray ionization (negative ion-ESI). (J Am Soc Mass Spectrom 2007, 18, 1789 -1798) © 2007 American Society for Mass Spectrometry I t is well known that liquid chromatography mass spectrometry (LC/MS) favors the analysis of polar compounds, as acid-base solution reactions are the most commonly observed ionization mechanism when using electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI). Traditionally, gas chromatography mass spectrometry (GC/MS) using both electron ionization (EI) and chemical ionization (CI) is employed for the analysis of volatile and thermostable nonpolar compounds. However, it can become difficult to analyze nonvolatile and/or thermo-labile nonpolar compounds via hyphenated techniques of chromatography and MS.In the year 2000, atmospheric pressure photoionization (APPI) [1] was developed as a complement to LC/ESI-MS and LC/APCI-MS. Presently, two fundamentally different APPI sources are commercially available [1,2]. Syagen Technology (Tustin, CA) produces PhotoMate, and Applied Biosystems/MDS SCIEX (Concord, Ontario, Canada) markets PhotoSpray. In both designs, photons emitted by a krypton discharge lamp are used to initiate a series of gas-phase reactions, which finally lead to analyte ionization. However, they differ in that PhotoMate utilizes a design to enhance direct APPI, while PhotoSpray implements a design using a dopant, usually tolu...

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“…The unusually high yield of ionization products led us to propose an EC ionization mechanism, which has previously been extremely successful in trace level analysis, most familiarly in the forms of EC-NICI 53 and EC-APCI. 54 An EC ionization mechanism for negative-ion APPI has been further proven by the fact that pentafluorobenzyl (PFB)-derivatized phenols readily underwent dissociative EC reaction, a signature process of EC-NICI 55 and EC-APCI, 56 and generated exclusively negative phenolate ions.…”

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confidence: 99%

Electron capture atmospheric pressure photoionization mass spectrometry: analysis of fullerenes, perfluorinated compounds, and pentafluorobenzyl derivatives

Song

Wellman

Yao

et al. 2007

Rapid Comm Mass Spectrometry

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An electron capture (EC) ionization mechanism has been found to be highly efficient in negative-ion atmospheric pressure photoionization (APPI) for the analysis of compounds with positive electron affinity (EA). Using negative-ion APPI, we first report the sensitive detection of natural electrophores with limited polarity, such as fullerenes and perfluorinated compounds, by mass spectrometry (MS). Using direct infusion on a quadrupole time-of-flight (QTOF) mass spectrometer, the limits of detection (LODs) for C(60) and perfluoromethylcyclohexane were determined to be 0.15 pg (0.2 fmol) and 1 femtoliter (fL) ( approximately 1.5 pg or 4.3 fmol), respectively. As the EA of the analyte increases, the detection sensitivity is enhanced. Making use of the accurate mass measurement capability of the QTOF mass spectrometer, we were able to investigate the elemental composition of the ions in each spectrum and attribute the observed high sensitivity to an EC-initiated ionization process. The proposed EC ionization mechanism is further supported by the observation of a dissociative EC reaction of pentafluorobenzyl (PFB)-derivatized phenols. The analysis of phenols by EC-APPI of their PFB derivatives resulted in very high sensitivity, with the lowest reported LOD of approximately 0.17 pg (0.5 fmol) being for 2,4-dinitrophenol. For future LC/EC-APPI-MS applications, the effect of additives and solvents on sensitivity was also tested and reported.

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Electron-Capture Mass Spectrometry: A Powerful Tool in Biomedical Trace Level Analysis

Cited by 18 publications

References 107 publications

Liquid chromatography-electrospray ionization-mass spectrometry: the future of DNA adduct detection

Liquid chromatography-electrospray ionization-mass spectrometry: the future of DNA adduct detection

Negative ion-atmospheric pressure photoionization: Electron capture, dissociative electron capture, proton transfer, and anion attachment

Electron capture atmospheric pressure photoionization mass spectrometry: analysis of fullerenes, perfluorinated compounds, and pentafluorobenzyl derivatives

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