scholarly journals Comparison of different real time VOC measurement techniques in a ponderosa pine forest

2012 ◽  
Vol 12 (10) ◽  
pp. 27955-27988 ◽  
Author(s):  
L. Kaser ◽  
T. Karl ◽  
R. Schnitzhofer ◽  
M. Graus ◽  
I. S. Herdlinger-Blatt ◽  
...  
Keyword(s):  
Proton Transfer ◽  
Mass Spectrometer ◽  
Ponderosa Pine ◽  
Transfer Reaction ◽  
Thermal Dissociation ◽  
Proton Transfer Reaction ◽  
Ionization Mass ◽  
Mixing Ratios ◽  
Relative Contribution ◽  
Tof Ms

Abstract. Volatile organic compound (VOC) mixing ratios measured by five independent instruments are compared at a forested site dominated by ponderosa pine (Pinus Ponderosa) during the BEACHON-ROCS field study in summer 2010. The instruments included a Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-TOF-MS), a Proton Transfer Reaction Quadrupole Mass Spectrometer (PTR-MS), a Fast Online Gas-Chromatograph coupled to a Mass Spectrometer (GC/MS; TOGA), a Thermal Dissociation Chemical Ionization Mass Spectrometer (PAN-CIMS) and a Fiber Laser-Induced Fluorescence Instrument (FILIF). The species discussed in this comparison include the most important biogenic VOCs and a selected suite of oxygenated VOCs that are thought to dominate the VOC reactivity at this particular site as well as typical anthropogenic VOCs that showed low mixing ratios at this site. Good agreement was observed for methanol, the sum of the oxygenated hemiterpene 2-methyl-3-buten-2-ol (MBO) and the hemiterpene isoprene, acetaldehyde, the sum of acetone and propanal, benzene and the sum of methyl ethyl ketone (MEK) and butanal. Measurements of the above VOCs conducted by different instruments agree within 20%. The ability to differentiate the presence of toluene and cymene by PTR-TOF-MS is tested based on a comparison with GC-MS measurements, suggesting a study-average relative contribution of 74% for toluene and 26% for cymene. Similarly, 2-hydroxy-2-methylpropanal (HMPR) is found to interfere with the sum of methyl vinyl ketone and methacrolein (MVK+MAC) using PTR-(TOF)-MS at this site. A study-average relative contribution of 85% for MVK+MAC and 15% for HMPR was determined. The sum of monoterpenes measured by PTR-MS and PTR-TOF-MS was generally 20–25% higher than the sum of speciated monoterpenes measured by TOGA, which included α-pinene, β-pinene, camphene, carene, myrcene, limonene, cineole as well as other terpenes. However, this difference is consistent throughout the study, and likely points to an offset in calibration, rather than a difference in the ability to measure the sum of terpenes. The contribution of isoprene relative to MBO inferred from PTR-MS and PTR-TOF-MS was smaller than 12% while GC-MS data suggested an average of 21% of isoprene relative to MBO. This comparison demonstrates that the current capability of VOC measurements to account for OH reactivity associated with the measured VOCs is within 20%.

scholarly journals Comparison of different real time VOC measurement techniques in a ponderosa pine forest

2013 ◽  
Vol 13 (5) ◽  
pp. 2893-2906 ◽  
Author(s):  
L. Kaser ◽  
T. Karl ◽  
R. Schnitzhofer ◽  
M. Graus ◽  
I. S. Herdlinger-Blatt ◽  
...  
Keyword(s):  
Proton Transfer ◽  
Mass Spectrometer ◽  
Ponderosa Pine ◽  
Transfer Reaction ◽  
Thermal Dissociation ◽  
Proton Transfer Reaction ◽  
Ionization Mass ◽  
Mixing Ratios ◽  
Relative Contribution ◽  
Tof Ms

Abstract. Volatile organic compound (VOC) mixing ratios measured by five independent instruments are compared at a forested site dominated by ponderosa pine (Pinus Ponderosa) during the BEACHON-ROCS field study in summer 2010. The instruments included a Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-TOF-MS), a Proton Transfer Reaction Quadrupole Mass Spectrometer (PTR-MS), a Fast Online Gas-Chromatograph coupled to a Mass Spectrometer (GC/MS; TOGA), a Thermal Dissociation Chemical Ionization Mass Spectrometer (PAN-CIMS) and a Fiber Laser-Induced Fluorescence Instrument (FILIF). The species discussed in this comparison include the most important biogenic VOCs and a selected suite of oxygenated VOCs that are thought to dominate the VOC reactivity at this particular site as well as typical anthropogenic VOCs that showed low mixing ratios at this site. Good agreement was observed for methanol, the sum of the oxygenated hemiterpene 2-methyl-3-buten-2-ol (MBO) and the hemiterpene isoprene, acetaldehyde, the sum of acetone and propanal, benzene and the sum of methyl ethyl ketone (MEK) and butanal. Measurements of the above VOCs conducted by different instruments agree within 20%. The ability to differentiate the presence of toluene and cymene by PTR-TOF-MS is tested based on a comparison with GC-MS measurements, suggesting a study-average relative contribution of 74% for toluene and 26% for cymene. Similarly, 2-hydroxy-2-methylpropanal (HMPR) is found to interfere with the sum of methyl vinyl ketone and methacrolein (MVK + MAC) using PTR-(TOF)-MS at this site. A study-average relative contribution of 85% for MVK + MAC and 15% for HMPR was determined. The sum of monoterpenes measured by PTR-MS and PTR-TOF-MS was generally 20–25% higher than the sum of speciated monoterpenes measured by TOGA, which included α-pinene, β-pinene, camphene, carene, myrcene, limonene, cineole as well as other terpenes. However, this difference is consistent throughout the study, and likely points to an offset in calibration, rather than a difference in the ability to measure the sum of terpenes. The contribution of isoprene relative to MBO inferred from PTR-MS and PTR-TOF-MS was smaller than 12% while GC-MS data suggested an average of 21% of isoprene relative to MBO. This comparison demonstrates that the current capability of VOC measurements to account for OH reactivity associated with the measured VOCs is within 20%.

scholarly journals Gas-to-particle partitioning of major biogenic oxidation products: a study on freshly formed and aged biogenic SOA

2018 ◽  
Vol 18 (17) ◽  
pp. 12969-12989 ◽  
Author(s):  
Georgios I. Gkatzelis ◽  
Thorsten Hohaus ◽  
Ralf Tillmann ◽  
Iulia Gensch ◽  
Markus Müller ◽  
...  
Keyword(s):  
Proton Transfer ◽  
Organic Compounds ◽  
Mass Spectrometer ◽  
Transfer Reaction ◽  
Theoretical Calculations ◽  
Proton Transfer Reaction ◽  
Oxidation Products ◽  
Particle Phase ◽  
Tof Ms ◽  
Good Agreement

Abstract. Secondary organic aerosols (SOAs) play a key role in climate change and air quality. Determining the fundamental parameters that distribute organic compounds between the phases is essential, as atmospheric lifetime and impacts change drastically between the gas and particle phase. In this work, gas-to-particle partitioning of major biogenic oxidation products was investigated using three different aerosol chemical characterization techniques. The aerosol collection module, the collection thermal desorption unit, and the chemical analysis of aerosols online are different aerosol sampling inlets connected to a proton-transfer reaction time-of-flight mass spectrometer (ACM-PTR-ToF-MS, TD-PTR-ToF-MS, and CHARON-PTR-ToF-MS, respectively, referred to hereafter as ACM, TD, and CHARON). These techniques were deployed at the atmosphere simulation chamber SAPHIR to perform experiments on the SOA formation and aging from different monoterpenes (β-pinene, limonene) and real plant emissions (Pinus sylvestris L.). The saturation mass concentration C* and thus the volatility of the individual ions was determined based on the simultaneous measurement of their signal in the gas and particle phase. A method to identify and exclude ions affected by thermal dissociation during desorption and ionic dissociation in the ionization chamber of the proton-transfer reaction mass spectrometer (PTR-MS) was developed and tested for each technique. Narrow volatility distributions with organic compounds in the semi-volatile (SVOCs – semi-volatile organic compounds) to intermediate-volatility (IVOCs – intermediate-volatility organic compounds) regime were found for all systems studied. Despite significant differences in the aerosol collection and desorption methods of the proton-transfer-reaction (PTR)-based techniques, a comparison of the C* values obtained with different techniques was found to be in good agreement (within 1 order of magnitude) with deviations explained by the different operating conditions of the PTR-MS. The C* of the identified organic compounds were mapped onto the two-dimensional volatility basis set (2D-VBS), and results showed a decrease in C* with increasing oxidation state. For all experiments conducted in this study, identified partitioning organic compounds accounted for 20–30 % of the total organic mass measured from an aerosol mass spectrometer (AMS). Further comparison between observations and theoretical calculations was performed for species found in our experiments that were also identified in previous publications. Theoretical calculations based on the molecular structure of the compounds showed, within the uncertainties ranges, good agreement with the experimental C* for most SVOCs, while IVOCs deviated by up to a factor of 300. These latter differences are discussed in relation to two main processes affecting these systems: (i) possible interferences by thermal and ionic fragmentation of higher molecular-weight compounds, produced by accretion and oligomerization reactions, that fragment in the m∕z range detected by the PTR-MS and (ii) kinetic influences in the distribution between the gas and particle phase with gas-phase condensation, diffusion in the particle phase, and irreversible uptake.

scholarly journals A high-resolution time-of-flight chemical ionization mass spectrometer utilizing hydronium ions (H<sub>3</sub>O<sup>+</sup> ToF-CIMS) for measurements of volatile organic compounds in the atmosphere

2016 ◽  
Author(s):  
Bin Yuan ◽  
Abigail Koss ◽  
Carsten Warneke ◽  
Jessica B. Gilman ◽  
Brian M. Lerner ◽  
...  
Keyword(s):  
High Resolution ◽  
Proton Transfer ◽  
Mass Spectrometer ◽  
Chemical Ionization ◽  
Transfer Reaction ◽  
Proton Transfer Reaction ◽  
Reaction Mass ◽  
Ionization Mass ◽  
Hydronium Ions ◽  
Volatile Organic

Abstract. Proton transfer reactions between hydronium ions (H3O+) and volatile organic compounds (VOCs) provide a fast and high sensitive measurement technique for VOCs, leading to extensive use of proton-transfer-reaction mass spectrometry (PTR-MS) in atmospheric research. Based on the same ionization approach, we describe the development of a high-resolution (HR) time of flight chemical ionization mass spectrometer (ToF-CIMS) utilizing H3O+ as the reagent ions. The new H3O+ ToF-CIMS has sensitivities of 100–1000 cps/ppb (ion counts per second per part-per-billion mixing ratio of VOC) and detection limits of 20–600 ppt at 3σ for a 1-second integration time for simultaneous measurements of many VOC species of atmospheric relevance. Compared with similar instruments with quadrupole mass spectrometer, e.g. proton-transfer-reaction mass spectrometers, the ToF analyzer with mass resolution (m/Δm) of up to 6000 not only increases measurement frequency of the instrument, but also expands the number of measurable species. The humidity dependence of the instrument was characterized for various VOC species and the behaviors for different species can be explained by compound-specific properties that affect the ion chemistry. The new H3O+ ToF-CIMS was successfully deployed on the NOAA WP-3D research aircraft for the SONGNEX campaign in spring of 2015. The measured mixing ratios of several aromatics from the H3O+ ToF-CIMS agreed within ±10 % with independent gas chromatography (GC) measurements from whole air samples. Initial results from the SONGNEX measurements demonstrate that the H3O+ ToF-CIMS dataset will be valuable for the identification and characterization of emissions from various sources, investigation of secondary formation of many photochemical organic products and therefore the chemical evolution of gas-phase organic carbon in the atmosphere.

scholarly journals Measurements of OVOC fluxes by eddy covariance using a proton-transfer-reaction mass spectrometer – method development at a coastal site

2013 ◽  
Vol 13 (13) ◽  
pp. 6165-6184 ◽  
Author(s):  
M. Yang ◽  
R. Beale ◽  
T. Smyth ◽  
B. Blomquist
Keyword(s):  
Proton Transfer ◽  
Eddy Covariance ◽  
Mass Spectrometer ◽  
Transfer Reaction ◽  
Proton Transfer Reaction ◽  
Time Of Day ◽  
Reaction Mass ◽  
Mixing Ratio ◽  
Mixing Ratios ◽  
Vertical Fluxes

Abstract. We present here vertical fluxes of oxygenated volatile organic compounds (OVOCs) measured with eddy covariance (EC) during the period of March to July 2012 near the southwest coast of the United Kingdom. The performance of the proton-transfer-reaction mass spectrometer (PTR-MS) for flux measurement is characterized, with additional considerations given to the homogeneity and stationarity assumptions required by EC. Observed mixing ratios and fluxes of OVOCs (specifically methanol, acetaldehyde, and acetone) vary significantly with time of day and wind direction. Higher mixing ratios and fluxes of acetaldehyde and acetone are found in the daytime and from the direction of a forested park, most likely due to light-driven emissions from terrestrial plants. Methanol mixing ratio and flux do not demonstrate consistent diel variability, suggesting sources in addition to plants. We estimate air–sea exchange and photochemical rates of these compounds, which are compared to measured vertical fluxes. For acetaldehyde, the mean (1σ) mixing ratio of 0.13 (0.02) ppb at night may be maintained by oceanic emission, while photochemical destruction outpaces production during the day. Air–sea exchange and photochemistry are probably net sinks of methanol and acetone in this region. Their nighttime mixing ratios of 0.46 (0.20) and 0.39 (0.08) ppb appear to be affected more by terrestrial emissions and long-distance transport, respectively.

scholarly journals Glyoxal measurement with a proton transfer reaction time of flight mass spectrometer (PTR-TOF-MS): characterization and calibration

2016 ◽  
Vol 52 (1) ◽  
pp. 30-35 ◽  
Author(s):  
Christof Stönner ◽  
Bettina Derstroff ◽  
Thomas Klüpfel ◽  
John N. Crowley ◽  
Jonathan Williams
Keyword(s):  
Reaction Time ◽  
Proton Transfer ◽  
Mass Spectrometer ◽  
Transfer Reaction ◽  
Time Of Flight ◽  
Proton Transfer Reaction ◽  
Flight Mass Spectrometer ◽  
Tof Ms

scholarly journals Segmented flow coil equilibrator coupled to a proton-transfer-reaction mass spectrometer for measurements of a broad range of volatile organic compounds in seawater

Ocean Science ◽  
2019 ◽  
Vol 15 (4) ◽  
pp. 925-940 ◽  
Author(s):  
Charel Wohl ◽  
David Capelle ◽  
Anna Jones ◽  
William T. Sturges ◽  
Philip D. Nightingale ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Gas Exchange ◽  
Proton Transfer ◽  
Organic Compounds ◽  
Mass Spectrometer ◽  
Transfer Reaction ◽  
Proton Transfer Reaction ◽  
Reaction Mass ◽  
Segmented Flow ◽  
Volatile Organic

Abstract. We present a technique that utilises a segmented flow coil equilibrator coupled to a proton-transfer-reaction mass spectrometer to measure a broad range of dissolved volatile organic compounds. Thanks to its relatively large surface area for gas exchange, small internal volume, and smooth headspace–water separation, the equilibrator is highly efficient for gas exchange and has a fast response time (under 1 min). The system allows for both continuous and discrete measurements of volatile organic compounds in seawater due to its low sample water flow (100 cm3 min−1) and the ease of changing sample intake. The equilibrator setup is both relatively inexpensive and compact. Hence, it can be easily reproduced and installed on a variety of oceanic platforms, particularly where space is limited. The internal area of the equilibrator is smooth and unreactive. Thus, the segmented flow coil equilibrator is expected to be less sensitive to biofouling and easier to clean than membrane-based equilibration systems. The equilibrator described here fully equilibrates for gases that are similarly soluble or more soluble than toluene and can easily be modified to fully equilibrate for even less soluble gases. The method has been successfully deployed in the Canadian Arctic. Some example data from underway surface water and Niskin bottle measurements in the sea ice zone are presented to illustrate the efficacy of this measurement system.

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