Volatile organic compound analysis by pulsed glow discharge time of flight mass spectrometry as a structural elucidation tool

Abstract

Pulsed glow discharge (PGD) coupled to time of flight mass spectrometry (TOFMS) has been investigated for volatile organic compound (VOC) identification and determination. Optimization of PGD operational conditions (chamber design, applied power, pressure and duty cycle) was performed using acetone and benzene as model compounds. During the different optimizations, molecular, fragment and elemental information were obtained when characteristic GD pulse regions were measured. An exploratory study for several VOCs (lineal hydrocarbons, oxygen-containing compounds and aromatic compounds) revealed the capability of the PGD to provide crucial information to elucidate structures (fragments), molecular ions or even proton affinity nature of the molecules; this last information is a consequence of the enriched proton environment generated along the afterglow region for the ionization chamber used. Analytical characteristics were evaluated with solid phase microextraction-gas chromatography coupled to PGD-TOFMS for special aromatic hydrocarbons (benzene, toluene, ethylbenzene, xylene: BTEX) in water, showing a good performance in terms of reproducibility and sensitivity. Copyright © 2017 John Wiley & Sons, Ltd.

New Possibilities for the Determination of Volatile Organic Compounds by Their Molecular Ions in Air Using µs-Pulsed GD TOFMS

“…The LOD values in the range of 0.5-5 ppb were achieved, which is perspective for the real application of the new approach for a wide range of analytical tasks, including the determination of VOCs in human exhalation. 15,16 When comparing our results with previous studies, 1,3,5 the following aspects may be identified. The combination of several factors related to the nature of the pulsed glow discharge resulted in the combination of two beneficial outcomes for the online detection mode, which are often hard to achieve together.…”

“…Bouza et al also used the Penning mechanism for VOC ionisation. 1 However, since Ar* rather than N2* was used for the ionisation, which has a higher excitation energy (the difference of 0.66 eV), it resulted in a significantly higher fragmentation level for the VOCs. 1 Besides, we used a relatively low discharge power of 3 W, additionally reducing the degree of fragmentation.…”

“…1 However, since Ar* rather than N2* was used for the ionisation, which has a higher excitation energy (the difference of 0.66 eV), it resulted in a significantly higher fragmentation level for the VOCs. 1 Besides, we used a relatively low discharge power of 3 W, additionally reducing the degree of fragmentation. In our previous study, 5 we used copper-associates CuM + for the detection of VOCs and observed a low degree of fragmentation under the discharge parameters favouring their formation; however, it resulted in more than one order of magnitude reduced sensitivity compared to the use of molecular ions as in the current study.…”

“…1,2 Several studies addressed the application of glow discharge mass spectrometry (GDMS) in molecular analysis. [1][2][3][4][5] Fandino et al investigated two variants of GDMS application: as a detector in gas chromatography and under a continuous flow of VOCs (benzene, toluene, ethylbenzene, and xylene) in an artificial air mixture. 3 The afterglow of the discharge was used for the ionisation, employing mainly the Penning process.…”

Kinetic Understanding of the Ultrahigh Ionization Efficiencies (up to 28%) of Excited-State CH2Cl2-Induced Associative Ionization: A Case Study with Nitro Compounds

“…Complex ionization methods such as atmospheric pressure chemical ionization (APCI), − dielectric-barrier discharge ionization (DBDI), − and glow discharge , are also common ionization technologies that have been developed for the direct sensitive detection of volatile organic or inorganic compounds. In the process of complex ionization, all or parts of EI, SPI, CI, and Penning ionization may co-occur in the ionization region.…”