scholarly journals An <i>in situ</i> gas chromatograph with automatic detector switching between Vocus PTR-TOF-MS and EI-TOF-MS: Isomer resolved measurements of indoor air

2020 ◽  
Author(s):  
Megan S. Claflin ◽  
Demetrios Pagonis ◽  
Zachary Finewax ◽  
Anne V. Handschy ◽  
Douglas A. Day ◽  
...  
Keyword(s):  
Indoor Environment ◽  
Proton Transfer Reaction ◽  
Heterogeneous Reactions ◽  
Fast Time ◽  
Fragmentation Pattern ◽  
Gas Chromatograph ◽  
Mass Spectrometers ◽  
Mass Spectral ◽  
Tof Ms

Abstract. We have developed a field-deployable gas chromatograph (GC) with thermal desorption preconcentration (TDPC), which is demonstrated here with automatic detector switching between two high-resolution time-of-flight mass spectrometers (TOF-MS) for in situ measurements of volatile organic compounds (VOCs). This system provides many analytical advances including acquisition of fast time-response data in tandem with molecular speciation and two types of mass spectral information for each resolved GC peak: molecular ion identification from Vocus proton transfer reaction (PTR) TOF-MS and fragmentation pattern from electron ionization (EI) TOF-MS detection. This system was deployed during the 2018 ATHLETIC campaign at the University of Colorado Dal Ward Athletic Center in Boulder, Colorado where it was used to characterize VOC emissions in the indoor environment. The addition of the TDPC-GC increased the Vocus sensitivity by a factor of 50 due to preconcentration over a 6 min GC sample time versus direct air sampling with the Vocus which was operated with a time resolution of 1 Hz. The GC-TOF methods demonstrated average limits of detection of 1.6 ppt across a range of monoterpenes and aromatics. Here, we describe the method to use the two-detector system to conclusively identify a range of VOCs including hydrocarbons, oxygenates and halocarbons, along with detailed results including the quantification of anthropogenic monoterpenes, where limonene accounted for 47–80 % of the indoor monoterpene composition. We also report the detection of dimethylsilanediol (DMSD), an organosiloxane degradation product, which was observed with dynamic temporal behavior distinct from volatile organosiloxanes (e.g. decamethylcyclopentasiloxane, D5 siloxane). Our results suggest DMSD is produced from humidity-dependent, heterogeneous reactions occurring on surfaces in the indoor environment, rather than formed through gas-phase oxidation of volatile siloxanes.

scholarly journals An in situ gas chromatograph with automatic detector switching between PTR- and EI-TOF-MS: isomer-resolved measurements of indoor air

2021 ◽  
Vol 14 (1) ◽  
pp. 133-152
Author(s):  
Megan S. Claflin ◽  
Demetrios Pagonis ◽  
Zachary Finewax ◽  
Anne V. Handschy ◽  
Douglas A. Day ◽  
...  
Keyword(s):  
Indoor Environment ◽  
Proton Transfer Reaction ◽  
Heterogeneous Reactions ◽  
Fast Time ◽  
Fragmentation Pattern ◽  
Gas Chromatograph ◽  
Mass Spectrometers ◽  
Mass Spectral ◽  
Tof Ms

Abstract. We have developed a field-deployable gas chromatograph (GC) with thermal desorption preconcentration (TDPC), which is demonstrated here with automatic detector switching between two high-resolution time-of-flight mass spectrometers (TOF-MSs) for in situ measurements of volatile organic compounds (VOCs). This system provides many analytical advances, including acquisition of fast time–response data in tandem with molecular speciation and two types of mass spectral information for each resolved GC peak: molecular ion identification from Vocus proton transfer reaction (PTR) TOF-MS and fragmentation pattern from electron ionization (EI) TOF-MS detection. This system was deployed during the 2018 ATHLETIC campaign at the University of Colorado Dal Ward Athletic Center in Boulder, Colorado, where it was used to characterize VOC emissions in the indoor environment. The addition of the TDPC-GC increased the Vocus sensitivity by a factor of 50 due to preconcentration over a 6 min GC sample time versus direct air sampling with the Vocus, which was operated with a time resolution of 1 Hz. The GC-TOF methods demonstrated average limits of detection of 1.6 ppt across a range of monoterpenes and aromatics. Here, we describe the method to use the two-detector system to conclusively identify a range of VOCs including hydrocarbons, oxygenates, and halocarbons, along with detailed results including the quantification of anthropogenic monoterpenes, where limonene accounted for 47 %–80 % of the indoor monoterpene composition. We also report the detection of dimethylsilanediol (DMSD), an organosiloxane degradation product, which was observed with dynamic temporal behavior distinct from volatile organosiloxanes (e.g., decamethylcyclopentasiloxane, D5 siloxane). Our results suggest DMSD is produced from humidity-dependent heterogeneous reactions occurring on surfaces in the indoor environment, rather than formed through gas-phase oxidation of volatile siloxanes.

scholarly journals PTRwid: a new widget-tool for processing PTR-TOF-MS data

2015 ◽  
Vol 8 (2) ◽  
pp. 1629-1669 ◽  
Author(s):  
R. Holzinger
Keyword(s):  
Comprehensive Evaluation ◽  
Time Of Flight ◽  
Proton Transfer Reaction ◽  
Mass Scale ◽  
Process Data ◽  
Mass Spectrometers ◽  
Scale Calibration ◽  
Field Campaigns ◽  
User Friendly ◽  
Tof Ms

Abstract. PTRwid is a fast and user friendly tool that has been developed to process data from proton-transfer-reaction time-of-flight mass-spectrometers (PTR-TOF-MS) that use HTOF time-of-flight mass-spectrometers from Tofwerk AG (Switzerland). PTRwid is designed for a comprehensive evaluation of whole laboratory or field based studies. All processing runs autonomously and whole laboratory or field campaigns can, in principle, be processed with a few mouse clicks. Unique features of PTRwid include (i) an autonomous and accurate mass scale calibration, (ii) the computation of an "Unified Mass list" that – in addition to an uniform data structure – provides a robust method to determine the precision of attributed peak masses, and (iii) fast data analysis due to well considered choices in data processing.

scholarly journals UPLC-QTOF-MS Method for Identification of Mango Leaf Tea Metabolites

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 1736-1736
Author(s):  
Sepideh Alasvand ◽  
Hyun-Jin Kim ◽  
Vivian Haley-Zitlin
Keyword(s):  
Flow Rate ◽  
High Performance ◽  
Mass Measurement ◽  
Fragmentation Pattern ◽  
Column Temperature ◽  
Mass Spectral ◽  
Scan Time ◽  
Positive Mode ◽  
Acquity Uplc ◽  
Tof Ms

Abstract Objectives The study aim was to identify bioactive compounds in mango leaf tea using a new method - UPLC/Q-TOF-MS. Mango leaf tea is a natural product being investigated to manage type 2 diabetes due to its phytochemical properties. Methods Mango tea was extracted using 80% methanol overnight. The extract was analyzed with ultra-high-performance liquid chromatography-quadrupole time-of-flight (UPLC-Q-TOF) MS system (Waters Corp., Milford, MA) and injected into an Acquity UPLC BEH C18 column (2.1 mm × 100 mm, 1.7 µm, Waters Corp.). The column was equilibrated with distilled water containing 0.1% formic acid (FA) and eluted by a linear gradient of acetonitrile (ACN) containing 0.1% FA at a flow rate of 0.35 mL/min for 10 min and 40 °C of column temperature. Results The eluents were analyzed by A Vion IMS Q-TOF MS (Waters Corp.) with positive and negative electrospray ionization (ESI). The scan range of TOF MS data was 50–1500 m/z, the scan time was 0.2 sec, and the capillary and sampling cone voltages were 3 kV and 40 V, respectively. The desolvation flow rate and temperature were 800 L/h and 400 °C, respectively, and the source temperature was 100 °C. Leucine-enkephalin ([M + H] = 556.2771 Da; [M-H] = 554.2615 Da), used as a lack mass, was infused at a flow rate of 0.35 μL/min and a frequency of 10 s to ensure mass measurement accuracy of the metabolites analyzed by the instrument. Mass spectral data were collected from m/z 50 to 1500 with a scan time of 0.2 s. Collision energy was ramped from 10 to 40 eV for the collection of MS/MS data. The metabolites Mangiferin, quercetin/isoquercetin and iriflophenone 3-beta-glucoside were identified using ChemSpider in negative mode while only mangiferin and quercetin were defined in positive mode with different intensites: Mangiferin (421.07), quercetin/isoquercetin (303.05) and irrflophenone 3- beta- glucoside (407.097) that confirmed their molar mass. Conclusions The UPLC/Q-TOF-MS technique is a practical and novel method for identifying the fragmentation pattern of metabolites in mango leaf tea by measuring accurate mass with excellent resolution and sensitivity. Funding Sources N/A.

scholarly journals Organic aerosol composition measurements with advanced offline and in-situ techniques during the CalNex campaign

2014 ◽  
Vol 7 (12) ◽  
pp. 12449-12480
Author(s):  
J. Timkovsky ◽  
A. W. H. Chan ◽  
T. Dorst ◽  
A. H. Goldstein ◽  
B. Oyama ◽  
...  
Keyword(s):  
Organic Aerosol ◽  
Proton Transfer Reaction ◽  
Quantitative Agreement ◽  
Aerosol Composition ◽  
In Situ Techniques ◽  
Sampling Artifacts ◽  
Alkanoic Acids ◽  
Molecular Masses ◽  
Tof Ms

Abstract. Our understanding of formation processes, physical properties and climate/health effects of organic aerosols is still limited in part due to limited knowledge of organic aerosol composition. We present speciated measurements of organic aerosol composition by two methods: in-situ thermal-desorption proton-transfer-reaction mass spectrometry (TD-PTR-MS) and offline two-dimensional gas chromatography with a time-of-flight mass spectrometer (GC×GC/TOF-MS). 153 compounds were identified using the GC×GC/TOF-MS, 123 of which were matched with 64 ions observed by the TD-PTR-MS. A reasonable overall correlation of 0.67 (r2) was found between the total matched TD-PTR-MS signal (sum of 64 ions) and the total matched GC×GC/TOF-MS signal (sum of 123 compounds). A reasonable quantitative agreement between the two methods was observed for most individual compounds with concentrations which were detected at levels above 2 ng m−3 using the GC×GC/TOF-MS. The analysis of monocarboxylic acids standards with TD-PTR-MS showed that alkanoic acids with molecular masses below 290 amu are detected well (recovery fractions above 60%). However, the concentrations of these acids were consistently higher on quartz filters (quantified offline by GC×GC/TOF-MS) than those suggested by in-situ TD-PTR-MS measurements, which is consistent with the semivolatile nature of the acids and corresponding positive filter sampling artifacts.

scholarly journals Comparison of advanced offline and in situ techniques of organic aerosol composition measurement during the CalNex campaign

2015 ◽  
Vol 8 (12) ◽  
pp. 5177-5187 ◽  
Author(s):  
J. Timkovsky ◽  
A. W. H. Chan ◽  
T. Dorst ◽  
A. H. Goldstein ◽  
B. Oyama ◽  
...  
Keyword(s):  
Los Angeles ◽  
Organic Aerosol ◽  
Proton Transfer Reaction ◽  
Quantitative Agreement ◽  
Aerosol Composition ◽  
In Situ Techniques ◽  
Molecular Masses ◽  
Composition Measurement ◽  
Tof Ms

Abstract. Our understanding of formation processes, physical properties, and climate/health effects of organic aerosols is still limited in part due to limited knowledge of organic aerosol composition. We present speciated measurements of organic aerosol composition by two methods: in situ thermal-desorption proton-transfer-reaction mass spectrometry (TD-PTR-MS) and offline two-dimensional gas chromatography with a time-of-flight mass spectrometer (GC × GC/TOF-MS). Using the GC × GC/TOF-MS 153 compounds were identified, 123 of which were matched with 64 ions observed by the TD-PTR-MS. A reasonable overall correlation of 0.67 (r2) was found between the total matched TD-PTR-MS signal (sum of 64 ions) and the total matched GC × GC/TOF-MS signal (sum of 123 compounds) for the Los Angeles area. A reasonable quantitative agreement between the two methods was observed for most individual compounds with concentrations which were detected at levels above 2 ng m−3 using the GC × GC/TOF-MS. The analysis of monocarboxylic acids standards with TD-PTR-MS showed that alkanoic acids with molecular masses below 290 amu are detected well (recovery fractions above 60 %). However, the concentrations of these acids were consistently higher on quartz filters (quantified offline by GC × GC/TOF-MS) than those suggested by in situ TD-PTR-MS measurements, which is consistent with the semivolatile nature of the acids and corresponding positive filter sampling artifacts.

scholarly journals PTRwid: A new widget tool for processing PTR-TOF-MS data

2015 ◽  
Vol 8 (9) ◽  
pp. 3903-3922 ◽  
Author(s):  
R. Holzinger
Keyword(s):  
Comprehensive Evaluation ◽  
Time Of Flight ◽  
Proton Transfer Reaction ◽  
Mass Scale ◽  
Process Data ◽  
Mass Spectrometers ◽  
Scale Calibration ◽  
Field Campaigns ◽  
User Friendly ◽  
Tof Ms

Abstract. PTRwid is a fast and user friendly tool that has been developed to process data from proton-transfer-reaction time-of-flight mass spectrometers (PTR-TOF-MS) that use HTOF (high-resolution time-of-flight) mass spectrometers from Tofwerk AG (Switzerland). PTRwid is designed for a comprehensive evaluation of whole laboratory or field-based studies. All processing runs autonomously, and entire laboratory or field campaigns can, in principle, be processed with a few mouse clicks. Unique features of PTRwid include (i) an autonomous and accurate mass scale calibration, (ii) the computation of a "unified mass list" that – in addition to a uniform data structure – provides a robust method to determine the precision of attributed peak masses, and (iii) fast data analysis due to well considered choices in data processing.

Development and Deployment of In-Situ Mass Spectrometers

2002 ◽  
Author(s):  
R. T. Short ◽  
Gottfried P. Kibelka ◽  
David P. Fries ◽  
Robert H. Byrne
Keyword(s):  
Mass Spectrometers

Development and Deployment of In-Situ Mass Spectrometers

2003 ◽  
Author(s):  
R. T. Short ◽  
David P. Fries ◽  
Robert H. Byrne
Keyword(s):  
Mass Spectrometers

scholarly journals Controlled density glycodendron microarrays for studying carbohydrate–lectin interactions

2021 ◽  
Author(s):  
Antonio Di Maio ◽  
Anna Cioce ◽  
Silvia Achilli ◽  
Michel Thépaut ◽  
Corinne Vivès ◽  
...  
Keyword(s):  
Maldi Tof Ms ◽  
Maldi Tof ◽  
On Chip ◽  
Tof Ms

Density depended binding and selectivity is studied on glycodendron microarray with defined valency, which were prepared by on-chip synthesis and analysed by in situ MALDI-TOF MS.

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