TY - JOUR
T1 - Glow discharge plasma ionization mass spectrometry for direct detection of oxygenated organic compounds in the gas-phase
AU - Nunome, Yoko
AU - Kodama, Kenji
AU - Wagatsuma, Kazuaki
N1 - Funding Information:
This work was supported by the Inter-University Cooperative Research Program of the Institute for Materials Research, Tohoku University (Proposal No. 18K0002).
Publisher Copyright:
© The Japan Society for Analytical Chemistry.
PY - 2020
Y1 - 2020
N2 - This study describes a direct analysis of oxygenated organic compounds, such as ketones, esters and ethers, rapidly and easily using a soft plasma ionization (SPI) source combined with a Q-mass spectrometer. A related molecular ion, [2M+H]+, in which a sample molecule (M) can undergo protonation via water clusters, such as [(H2O)n+H]+ and [N2(H2O)n+H]+, in an ambient air glow discharge plasma, can be dominantly detected as a base peak with little or no fragmentation at a pressure of several kPa. Oxygenated organic compounds with high proton affinity were found to generate their dimers through the hydrogen bonding interaction at higher pressures. A deuterated solvent was used to examine whether or not the adduct ion of analyte was derived from the solvent. The formation of [2M+H]+ strongly depended on the time. A two-dimensional spectrometer was used to obtain the distribution of several excited species and then to confirm the ionization reactions of the analyte in the SPI source. The sample molecule would be readily ionized through Penning-type collisions with excited N2, which causes fragmentation for oxygenated compounds due to the lower pressures (approx. 1.0 kPa) while it is ionized by an attachment with protons from water clusters at higher pressures (several kPa). The SPI source can be a new and powerful tool for soft ionization in direct analysis of volatile organic compounds (VOCs).
AB - This study describes a direct analysis of oxygenated organic compounds, such as ketones, esters and ethers, rapidly and easily using a soft plasma ionization (SPI) source combined with a Q-mass spectrometer. A related molecular ion, [2M+H]+, in which a sample molecule (M) can undergo protonation via water clusters, such as [(H2O)n+H]+ and [N2(H2O)n+H]+, in an ambient air glow discharge plasma, can be dominantly detected as a base peak with little or no fragmentation at a pressure of several kPa. Oxygenated organic compounds with high proton affinity were found to generate their dimers through the hydrogen bonding interaction at higher pressures. A deuterated solvent was used to examine whether or not the adduct ion of analyte was derived from the solvent. The formation of [2M+H]+ strongly depended on the time. A two-dimensional spectrometer was used to obtain the distribution of several excited species and then to confirm the ionization reactions of the analyte in the SPI source. The sample molecule would be readily ionized through Penning-type collisions with excited N2, which causes fragmentation for oxygenated compounds due to the lower pressures (approx. 1.0 kPa) while it is ionized by an attachment with protons from water clusters at higher pressures (several kPa). The SPI source can be a new and powerful tool for soft ionization in direct analysis of volatile organic compounds (VOCs).
KW - Ambient air
KW - Glow discharge plasma
KW - Mass spectrometry
KW - Oxygenated organic compounds
KW - Two-dimensional emission images
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U2 - 10.2116/analsci.19P252
DO - 10.2116/analsci.19P252
M3 - Article
C2 - 31611472
AN - SCOPUS:85079203919
VL - 36
SP - 269
EP - 276
JO - Analytical Sciences
JF - Analytical Sciences
SN - 0910-6340
IS - 2
ER -