Rationale: Dopants used with Atmospheric Pressure Photoionization (APPI) were examined with the Direct Analysis in Real Time (DART ) ion source operated with argon gas. Charge-exchange and proton transfer reactions were observed by adding toluene, anisole, chlorobenzene and acetone to the DART gas stream, complementing the information obtained by helium DART.
Methods: Mass spectra were acquired with a time-of-flight mass spectrometer equipped with a DART ion source operated with argon gas. A syringe pump was used to introduce dopants directly into the DART gas stream through deactivated fused-silica capillary tubing. Samples including polycyclic aromatic hydrocarbons (PAHs), diesel fuel, trinitrotoluene and cannabinoids were deposited onto the sealed end of melting tube, allowed to dry, and the tube was then suspended in the dopant-enhanced DART gas stream.
Results: PAHs could be detected as molecular ions at concentrations in the low parts-per-billion range by using a solution of 0.5% anisole in toluene as a dopant. Argon DART analysis of a diesel fuel sample with the same dopant mixture showed a simpler mass spectrum than obtained by using helium DART. The argon DART mass spectrum was dominated by molecular ions for aromatic compounds, whereas the helium DART mass spectrum showed both molecular ions and protonated molecules. In contrast O attachment DART showed saturated hydrocarbons and oxygen-containing species. Mass spectra for trinitrotoluene with argon DART in negative-ion mode showed a prominent [M - H] peak, whereas conventional helium DART showed both M and [M - H] . Lastly, in analogy to a report in the literature using APPI, positive ions produced by argon DART ionization for delta-9-tetrahydrocannabinol (THC) and cannabidiol showed distinctive product-ion mass spectra.
Conclusions: Dopant-assisted argon DART operates by a mechanism that is analogous to those proposed for dopant-assisted atmospheric-pressure photoionization. Copyright © 2016 John Wiley & Sons, Ltd.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1002/rcm.7552 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Direct analysis in real-time mass spectrometry: Observations of helium, nitrogen and argon as ionisation gas for the detection of small molecules using a single quadrupole instrument.
Rapid Commun Mass Spectrom
June 2023
School of Chemistry and Chemical Engineering, University of Surrey, Guildford, UK.
Rationale: Direct analysis in real time is typically performed using helium as the ionisation gas for the detection of analytes by mass spectrometry (MS). Nitrogen and argon are found with abundance in the air and provide a cheaper and greener alternative to the use of helium as ionisation gas. This study explores the use of helium, nitrogen and argon as ionisation gas for the detection of organic compounds.
View Article and Find Full Text PDFAtmospheric Pressure Dark-Current Argon Discharge Ionization with Comparable Performance to Direct Analysis in Real Time Mass Spectrometry.
Mass Spectrom (Tokyo)
October 2019
Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama 236-0027, Japan.
Herein, a dark-current discharge state created by combining argon flow with a needle electrode in ambient air is described that has an ionization efficiency and mechanism comparable to those of conventional helium direct analysis in real time (DART), without requiring dopants and DART glow discharge. Using this method, polar compounds such as α-amino acids were ionized in the dark-current argon discharge (de)protonation, molecular anion formation, fragmentation, (de)protonation with the attachment of oxygen, deprotonation with hydrogen loss and negative ion attachment. In contrast, nonpolar compounds (, -alkanes) were detected as positive ions hydride abstraction and oxidation.
View Article and Find Full Text PDFNitrogen-Activated Oxidation in Nitrogen Direct Analysis in Real Time Mass Spectrometry (DART-MS) and Rapid Detection of Explosives Using Thermal Desorption DART-MS.
J Am Soc Mass Spectrom
October 2019
Key Laboratory of Cluster Science, Ministry of Education of China; Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials; School of Chemistry, Beijing Institute of Technology, Beijing, 100081, China.
Direct analysis in real time mass spectrometry (DART-MS) was used to analyze an array of explosives including nitro-based explosives, peroxide explosives, and energetic heterocyclic compounds with different DART discharge gases (helium, argon, and nitrogen). Profound analyte oxidation was observed for particular compounds (TNT (9) and 2, 4-DNT (10)), whose mass spectra were completely dominated by the oxidation products when nitrogen was substituted for helium in DART analysis. This interesting phenomenon suggested that a highly oxidative environment provided by N DART ion source.
View Article and Find Full Text PDFSpatial distributions of furan and 5-hydroxymethylfurfural in unroasted and roasted Coffea arabica beans.
Food Res Int
May 2019
University at Albany-State University of New York, Department of Chemistry, 1400 Washington Avenue, Albany, NY 12222, USA. Electronic address:
For the first time, the spatial distributions of the highly volatile compounds furan and 5-hydroxymethylfurfural (HMF) have been determined in cross sections of green and roasted Coffea arabica beans. The image maps were revealed by laser ablation DART imaging mass spectrometry (LADI-MS). The presence of these compounds was independently confirmed by GC-MS as well as argon DART-MS.
View Article and Find Full Text PDFDopant-assisted direct analysis in real time mass spectrometry with argon gas.
Rapid Commun Mass Spectrom
May 2016
JEOL USA, Inc., 11 Dearborn Rd, Peabody, MA, 01960, USA.
Rationale: Dopants used with Atmospheric Pressure Photoionization (APPI) were examined with the Direct Analysis in Real Time (DART ) ion source operated with argon gas. Charge-exchange and proton transfer reactions were observed by adding toluene, anisole, chlorobenzene and acetone to the DART gas stream, complementing the information obtained by helium DART.
Methods: Mass spectra were acquired with a time-of-flight mass spectrometer equipped with a DART ion source operated with argon gas.
Want AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!