scholarly journals Experiments with the LECO Pegasus Gas Chromatograph/ Time-of-Flight Mass Spectrometer Phase 1: Fast GC Separations and Comparison of the GC/TOF-MS with Conventional Quadrupole GC/MS and Fast Quadrupole GC/MS

2012 ◽  
Author(s):  
H Mulcahy ◽  
C Koester
2019 ◽  
Vol 19 (12) ◽  
pp. 8037-8062 ◽  
Author(s):  
Lu Qi ◽  
Mindong Chen ◽  
Giulia Stefenelli ◽  
Veronika Pospisilova ◽  
Yandong Tong ◽  
...  

Abstract. Real-time, in situ molecular composition measurements of the organic fraction of fine particulate matter (PM2.5) remain challenging, hindering a full understanding of the climate impacts and health effects of PM2.5. In particular, the thermal decomposition and ionization-induced fragmentation affecting current techniques has limited a detailed investigation of secondary organic aerosol (SOA), which typically dominates OA. Here we deploy a novel extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF-MS) during winter 2017 in downtown Zurich, Switzerland, which overcomes these limitations, together with an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS) and supporting instrumentation. Positive matrix factorization (PMF) implemented within the Multilinear Engine (ME-2) program was applied to the EESI-TOF-MS data to quantify the primary and secondary contributions to OA. An 11-factor solution was selected as the best representation of the data, including five primary and six secondary factors. Primary factors showed influence from cooking, cigarette smoke, biomass burning (two factors) and a special local unknown event occurred only during two nights. Secondary factors were affected by biomass burning (three factors, distinguished by temperature and/or wind direction), organonitrates, monoterpene oxidation, and undetermined regional processing, in particular the contributions of wood combustion. While the AMS attributed slightly over half the OA mass to SOA but did not identify its source, the EESI-TOF-MS showed that most (>70 %) of the SOA was derived from biomass burning. Together with significant contributions from less aged biomass burning factors identified by both AMS and EESI-TOF-MS, this firmly establishes biomass burning as the single most important contributor to OA mass at this site during winter. High correlation was obtained between EESI-TOF-MS and AMS PMF factors where specific analogues existed, as well as between total signal and POA–SOA apportionment. This suggests the EESI-TOF-MS apportionment in the current study can be approximately taken at face value, despite ion-by-ion differences in relative sensitivity. The apportionment of specific ions measured by the EESI-TOF-MS (e.g., levoglucosan, nitrocatechol, and selected organic acids) and utilization of a cluster analysis-based approach to identify key marker ions for the EESI-TOF-MS factors are investigated. The interpretability of the EESI-TOF-MS results and improved source separation relative to the AMS within this pilot campaign validate the EESI-TOF-MS as a promising approach to source apportionment and atmospheric composition research.


2019 ◽  
Vol 19 (23) ◽  
pp. 14825-14848 ◽  
Author(s):  
Giulia Stefenelli ◽  
Veronika Pospisilova ◽  
Felipe D. Lopez-Hilfiker ◽  
Kaspar R. Daellenbach ◽  
Christoph Hüglin ◽  
...  

Abstract. Improving the understanding of the health and climate impacts of aerosols remains challenging and is restricted by the limitations of current measurement techniques. Detailed investigation of secondary organic aerosol (SOA), which is typically the dominating fraction of the organic aerosol (OA), requires instrumentation capable of real-time, in situ measurements of molecular composition. In this study, we present the first ambient measurements by a novel extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF-MS). The EESI-TOF-MS was deployed along with a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) during summer 2016 at an urban location (Zurich, Switzerland). Positive matrix factorization (PMF), implemented within the Multilinear Engine (ME-2), was applied to the data from both instruments to quantify the primary and secondary contributions to OA. From the EESI-TOF-MS analysis, a six-factor solution was selected as the most representative and interpretable solution for the investigated dataset, including two primary and four secondary factors. The primary factors are dominated by cooking and cigarette smoke signatures while the secondary factors are discriminated according to their daytime (two factors) and night-time (two factors) chemistry. All four factors showed strong influence by biogenic emissions but exhibited significant day–night differences. Factors dominating during daytime showed predominantly ions characteristic of monoterpene and sesquiterpene oxidation while the night-time factors included less oxygenated terpene oxidation products, as well as organonitrates which were likely derived from NO3 radical oxidation of monoterpenes. Overall, the signal measured by the EESI-TOF-MS and AMS showed a good correlation. Further, the two instruments were in excellent agreement in terms of both the mass contribution apportioned to the sum of POA and SOA factors and the total SOA signal. However, while the oxygenated organic aerosol (OOA) factors separated by AMS analysis exhibited a flat diurnal pattern, the EESI-TOF-MS factors illustrated significant chemical variation throughout the day. The captured variability, inaccessible from AMS PMF analysis, was shown to be consistent with the variations in the physiochemical processes influencing chemical composition and SOA formation. The improved source separation and interpretability of EESI-TOF-MS results suggest it to be a promising approach to source apportionment and atmospheric composition research.


2007 ◽  
Vol 7 (3) ◽  
pp. 609-620 ◽  
Author(s):  
K. P. Wyche ◽  
R. S. Blake ◽  
A. M. Ellis ◽  
P. S. Monks ◽  
T. Brauers ◽  
...  

Abstract. The performance of a new chemical ionization reaction time-of-flight mass spectrometer (CIR-TOF-MS) utilising the environment chamber SAPHIR (Simulation of Atmospheric Photochemistry In a large Reaction Chamber- Forschungzentrum Jülich, Germany) is described. The work took place as part of the ACCENT (Atmospheric Composition and Change the European NeTwork for excellence) supported oxygenated volatile organic compound (OVOC) measurement intercomparison during January 2005. The experiment entailed the measurement of 14 different atmospherically significant OVOCs at various mixing ratios in the approximate range 10.0–0.6 ppbV. The CIR-TOF-MS operated throughout the exercise with the hydronium ion (H3O+) as the primary chemical ionization (CI) reagent in order to facilitate proton transfer to the analyte OVOCs. The results presented show that the CIR time-of-flight mass spectrometer is capable of detecting a wide range of atmospheric OVOCs at mixing ratios of around 10 ppbV in "real-time" (i.e. detection on the one-minute time scale), with sub-ppbV measurement also achieved following an increase in averaging time to tens of minutes. It is shown that in general OVOC measurement is made with high accuracy and precision, with integration time, mixing ratio and compound dependent values as good as 4–13% and 3–15% respectively. It is demonstrated that CIR-TOF-MS has rapid multi-channel response at the required sensitivity, accuracy and precision for atmospheric OVOC measurement.


2016 ◽  
Author(s):  
Kermit K. Murray ◽  
Robert K. Boyd ◽  
Marcos N. Eberlin ◽  
G. John Langley ◽  
Liang Li ◽  
...  

RSC Advances ◽  
2016 ◽  
Vol 6 (15) ◽  
pp. 11952-11958 ◽  
Author(s):  
Jing-Hui Lv ◽  
Xian-Yong Wei ◽  
Ying-Hua Wang ◽  
Tie-Min Wang ◽  
Jing Liu ◽  
...  

The structural features of Zhundong subbituminous coal were investigated by RICO and subsequent analysis with a gas chromatograph/mass spectrometer and an atmospheric pressure solid-analysis probe/time of flight-mass spectrometer.


2017 ◽  
Vol 42 (1) ◽  
pp. 179-186
Author(s):  
Ushio Takeda ◽  
Takashi Kasamatsu ◽  
Yoshihiko Takinami ◽  
Takaya Satoh

2014 ◽  
Vol 16 (12) ◽  
pp. 2752-2757 ◽  
Author(s):  
Takahiro Anan ◽  
Shuichi Shimma ◽  
Yo Toma ◽  
Yasuyuki Hashidoko ◽  
Ryusuke Hatano ◽  
...  

The ability of simultaneous quantification of the gaseous compounds (CO2, N2O) emitted from soils within 1 minute have been demonstrated by using a fast gas chromatograph - multi-turn time-of-flight mass spectrometer.


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