TY - JOUR

T1 - Microsecond pulsed glow discharge in copper hollow cathode reveals a new approach to ionization and determination of volatile organic compounds

AU - Gubal, Anna

AU - Chuchina, Victoria

AU - Ivanenko, Natalya

AU - Qian, Rong

AU - Solovyev, Nikolay

AU - Ganeev, Alexander

N1 - Publisher Copyright: © 2020 Elsevier B.V.

PY - 2020/11

Y1 - 2020/11

N2 - Recently glow discharge (GD) mass spectrometry, which is conventionally used to analyze solid samples, was successfully applied for ionization and the subsequent determination of volatile organic compounds (VOCs). In the present study, the possibility of direct determination of VOCs in ambient air using time-of-flight mass spectrometry with microsecond pulsed discharge in a copper hollow cathode was considered for the first time. The discharge cell of the mass spectrometer was modified for the direct analysis of gaseous samples by the introduction of a quartz capillary into the argon input channel. Various classes of compounds (aromatic and aliphatic hydrocarbons and derivatives of carboxylic acids) were studied. Particular attention was paid to the ionization mechanisms of VOCs. New mechanisms of chemical and electron ionization, resulting in the formation of associate ions with cathode material (copper) – CuM+, were demonstrated and implemented. Alternative mechanisms of organic compounds ionization in GD may be related to Penning process and proton transfer reactions. These processes are mainly responsible for the formation of molecular and protonated molecular ions. The relative contribution of all these mechanisms can be adjusted by operating parameters. In general, an extremely low degree of fragmentation of molecular ions or associates was observed. Due to its isotopic structure (only two isotopes 63Cu and 65Cu with comparable abundances), the use of copper as cathode material additionally increases the reliability of VOC identification in the form of their CuM+ associates. Such association shifts the detected ions to the region of large masses with fewer interferences and noise related to scattered ions.

AB - Recently glow discharge (GD) mass spectrometry, which is conventionally used to analyze solid samples, was successfully applied for ionization and the subsequent determination of volatile organic compounds (VOCs). In the present study, the possibility of direct determination of VOCs in ambient air using time-of-flight mass spectrometry with microsecond pulsed discharge in a copper hollow cathode was considered for the first time. The discharge cell of the mass spectrometer was modified for the direct analysis of gaseous samples by the introduction of a quartz capillary into the argon input channel. Various classes of compounds (aromatic and aliphatic hydrocarbons and derivatives of carboxylic acids) were studied. Particular attention was paid to the ionization mechanisms of VOCs. New mechanisms of chemical and electron ionization, resulting in the formation of associate ions with cathode material (copper) – CuM+, were demonstrated and implemented. Alternative mechanisms of organic compounds ionization in GD may be related to Penning process and proton transfer reactions. These processes are mainly responsible for the formation of molecular and protonated molecular ions. The relative contribution of all these mechanisms can be adjusted by operating parameters. In general, an extremely low degree of fragmentation of molecular ions or associates was observed. Due to its isotopic structure (only two isotopes 63Cu and 65Cu with comparable abundances), the use of copper as cathode material additionally increases the reliability of VOC identification in the form of their CuM+ associates. Such association shifts the detected ions to the region of large masses with fewer interferences and noise related to scattered ions.

KW - Volatile organic compound

KW - Time-of-flight mass spectrometry

KW - Pulsed glow discharge

KW - Hollow cathode

KW - ionization

KW - Ionization

KW - HYDROCARBONS

KW - QUANTIFICATION

KW - ACQUISITION

KW - POTASSIUM TITANYL PHOSPHATE

KW - OXYGEN

KW - ELEMENTS

KW - FLIGHT MASS-SPECTROMETRY

KW - PLASMA

KW - FLUORINE

KW - CRYSTAL MATERIALS

UR - http://www.scopus.com/inward/record.url?scp=85091632087&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/8f425d90-3171-3ab8-8f23-e26c7f0e509d/

U2 - https://doi.org/10.1016/j.sab.2020.105986

DO - https://doi.org/10.1016/j.sab.2020.105986

M3 - Article

VL - 173

JO - SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY

JF - SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY

SN - 0584-8547

M1 - 105986

ER -