Determination and characterization of organic explosives using porous graphitic carbon and liquid chromatography–atmospheric pressure chemical ionization mass spectrometry

Holmgren, Erik; Carlsson, Håkan; Goede, Patrick; Crescenzi, Carlo

doi:10.1016/j.chroma.2005.08.088

Cited by 93 publications

(58 citation statements)

References 49 publications

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“…Holmgren et al [19] also reported an EC-APCI spectrum of 1,3,5-DNB with the following ions and relative ion intensity: 213 (86%), 183 (100%), 167 (2%), and 125 (4%).…”

Section: Ec and Dissociative Ecmentioning

confidence: 98%

“…Previously, Holmgren et al [19] reported an EC-APCI spectrum of 1,3-DNB with the following ions and relative ion intensity: 168 (46%), 138 (100%), and 108 (4%). Holmgren et al [19] also reported an EC-APCI spectrum of 1,3,5-DNB with the following ions and relative ion intensity: 213 (86%), 183 (100%), 167 (2%), and 125 (4%).…”

Section: Ec and Dissociative Ecmentioning

confidence: 99%

“…Fu et al [18] reported an EC-APCI spectrum of TNT with the following ions and relative ion intensity: m/z 245 (12.7%), 227 (100%), and 197 (59.1%). Holmgren et al [19] reported an EC-APCI spectrum of TNT with the following ions and relative ion intensity: m/z 227 (50%), 226 (50%), 210 (100%), 197 (69%), 180 (5%), 167 (15%), 152 (13%), 137 (9%), 124 (3%), and 109 (3%). Negative ion-APPI offers an obvious advantage over EC-NICI and EC-APCI with fewer ionization products.…”

Section: Ec and Proton Transfermentioning

confidence: 99%

“…However, no direct comparison of negative ion-APPI with EC-NICI, EC-APCI or negative ion-ESI was performed in this study. In previously published studies, Sigman et al [12] reported a LOD of 190 pg using GC/EC-NICI-MS and Holmgren et al [19] reported a LOD of 4.0 ng using LC/EC-APCI-MS.…”

Section: Ec and Proton Transfermentioning

confidence: 99%

“…However, their chloride attachment was so efficient that the limit of detection (LOD), defined by detection of their [M ϩ Cl] Ϫ ions at a signal to noise ratio (S/N) of 3, was estimated to be 424 and 64 fg or 1.9 and 0.2 fmol, respectively. Previously, Holmgren et al [19] reported the analysis of RDX and HMX by LC/negative ion-APCI-MS through chloride attachment with LOD of 3.3 and 1.7 ng, respectively. HMX was also analyzed via anion attachment by Pan et al [25] using LC/negative ion-ESI-MS.…”

Section: Anion Attachmentmentioning

confidence: 99%

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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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“…Holmgren et al [19] also reported an EC-APCI spectrum of 1,3,5-DNB with the following ions and relative ion intensity: 213 (86%), 183 (100%), 167 (2%), and 125 (4%).…”

Section: Ec and Dissociative Ecmentioning

confidence: 98%

Section: Ec and Dissociative Ecmentioning

confidence: 99%