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Liu L, Wang X, Chen J, Xue L, Wang W, Wen L, Li D, Chen T. Understanding unusually high levels of peroxyacetyl nitrate (PAN) in winter in Urban Jinan, China. J Environ Sci (China) 2018; 71:249-260. [PMID: 30195683 DOI: 10.1016/j.jes.2018.05.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 05/15/2018] [Accepted: 05/16/2018] [Indexed: 06/08/2023]
Abstract
Peroxyacetyl nitrate (PAN), as a major secondary pollutant, has gained increasing worldwide attentions, but relevant studies in China are still quite limited. During winter of 2015 to summer of 2016, the ambient levels of PAN were measured continuously by an automatic gas chromatograph equipped with an electron capture detector (GC-ECD) analyzer at an urban site in Jinan (China), with related parameters including concentrations of O3, NO, NO2, PM2.5, HONO, the photolysis rate constant of NO2 and meteorological factors observed concurrently. The mean and maximum values of PAN concentration were (1.89 ± 1.42) and 9.61 ppbv respectively in winter, and (2.54 ± 1.44) and 13.47 ppbv respectively in summer. Unusually high levels of PAN were observed during severe haze episodes in winter, and the formation mechanisms of them were emphatically discussed. Study showed that high levels of PAN in winter were mainly caused by local accumulation and strong photochemical reactions during haze episodes, while mass transport played only a minor role. Accelerated photochemical reactions (compared to winter days without haze) during haze episodes were deduced by the higher concentrations but shorter lifetimes of PAN, which was further supported by the sufficient solar radiation in the photolysis band along with the high concentrations of precursors (NO2, VOCs) and HONO during haze episodes. In addition, significant PAN accumulation during calm weather of haze episodes was verified by meteorological data.
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Affiliation(s)
- Lu Liu
- Environment Research Institute, School of Environmental Science and Engineering, Shandong University, Ji'nan 250100, China
| | - Xinfeng Wang
- Environment Research Institute, School of Environmental Science and Engineering, Shandong University, Ji'nan 250100, China
| | - Jianmin Chen
- Environment Research Institute, School of Environmental Science and Engineering, Shandong University, Ji'nan 250100, China; Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Institute of Atmospheric Sciences, Fudan University, Shanghai 200433, China; Institute for Climate and Global Change Research, School of Atmospheric Sciences, Nanjing University, Nanjing 210008, China.
| | - Likun Xue
- Environment Research Institute, School of Environmental Science and Engineering, Shandong University, Ji'nan 250100, China; Institute for Climate and Global Change Research, School of Atmospheric Sciences, Nanjing University, Nanjing 210008, China
| | - Wenxing Wang
- Environment Research Institute, School of Environmental Science and Engineering, Shandong University, Ji'nan 250100, China
| | - Liang Wen
- Environment Research Institute, School of Environmental Science and Engineering, Shandong University, Ji'nan 250100, China
| | - Dandan Li
- Environment Research Institute, School of Environmental Science and Engineering, Shandong University, Ji'nan 250100, China
| | - Tianshu Chen
- Environment Research Institute, School of Environmental Science and Engineering, Shandong University, Ji'nan 250100, China
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2
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Cai XM, Xu XX, Bian L, Luo ZX, Chen ZM. Measurement of volatile plant compounds in field ambient air by thermal desorption–gas chromatography–mass spectrometry. Anal Bioanal Chem 2015; 407:9105-14. [DOI: 10.1007/s00216-015-9076-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Revised: 09/14/2015] [Accepted: 09/23/2015] [Indexed: 11/30/2022]
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3
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Mellouki A, Wallington TJ, Chen J. Atmospheric chemistry of oxygenated volatile organic compounds: impacts on air quality and climate. Chem Rev 2015; 115:3984-4014. [PMID: 25828273 DOI: 10.1021/cr500549n] [Citation(s) in RCA: 211] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- A Mellouki
- Environment Research Institute, School of Environmental Science and Engineering, Shandong University, Ji'nan 250100, China.,ICARE/OSUC, CNRS, 45071 Orléans, France.,Systems Analytics and Environmental Sciences Department, Ford Motor Company, Mail Drop RIC-2122, Dearborn, Michigan 48121-2053, United States.,Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Fudan Tyndall Centre, Shanghai 200433, China.,Environment Research Institute, School of Environmental Science and Engineering, Shandong University, Ji'nan 250100, China
| | - T J Wallington
- Environment Research Institute, School of Environmental Science and Engineering, Shandong University, Ji'nan 250100, China.,ICARE/OSUC, CNRS, 45071 Orléans, France.,Systems Analytics and Environmental Sciences Department, Ford Motor Company, Mail Drop RIC-2122, Dearborn, Michigan 48121-2053, United States.,Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Fudan Tyndall Centre, Shanghai 200433, China.,Environment Research Institute, School of Environmental Science and Engineering, Shandong University, Ji'nan 250100, China
| | - J Chen
- Environment Research Institute, School of Environmental Science and Engineering, Shandong University, Ji'nan 250100, China.,ICARE/OSUC, CNRS, 45071 Orléans, France.,Systems Analytics and Environmental Sciences Department, Ford Motor Company, Mail Drop RIC-2122, Dearborn, Michigan 48121-2053, United States.,Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Fudan Tyndall Centre, Shanghai 200433, China.,Environment Research Institute, School of Environmental Science and Engineering, Shandong University, Ji'nan 250100, China
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Fischer EV, Jacob DJ, Yantosca RM, Sulprizio MP, Millet DB, Mao J, Paulot F, Singh HB, Roiger A, Ries L, Talbot R, Dzepina K, Pandey Deolal S. Atmospheric peroxyacetyl nitrate (PAN): a global budget and source attribution. ATMOSPHERIC CHEMISTRY AND PHYSICS 2014; 14:2679-2698. [PMID: 33758588 PMCID: PMC7983850 DOI: 10.5194/acp-14-2679-2014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Peroxyacetyl nitrate (PAN) formed in the atmospheric oxidation of non-methane volatile organic compounds (NMVOCs) is the principal tropospheric reservoir for nitrogen oxide radicals (NOx = NO + NO2). PAN enables the transport and release of NOx to the remote troposphere with major implications for the global distributions of ozone and OH, the main tropospheric oxidants. Simulation of PAN is a challenge for global models because of the dependence of PAN on vertical transport as well as complex and uncertain NMVOC sources and chemistry. Here we use an improved representation of NMVOCs in a global 3-D chemical transport model (GEOS-Chem) and show that it can simulate PAN observations from aircraft campaigns worldwide. The immediate carbonyl precursors for PAN formation include acetaldehyde (44% of the global source), methylglyoxal (30 %), acetone (7 %), and a suite of other isoprene and terpene oxidation products (19 %). A diversity of NMVOC emissions is responsible for PAN formation globally including isoprene (37 %) and alkanes (14 %). Anthropogenic sources are dominant in the extratropical Northern Hemisphere outside the growing season. Open fires appear to play little role except at high northern latitudes in spring, although results are very sensitive to plume chemistry and plume rise. Lightning NOx is the dominant contributor to the observed PAN maximum in the free troposphere over the South Atlantic.
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Affiliation(s)
- E. V. Fischer
- Department of Atmospheric Science, Colorado State University, Fort Collins, CO, USA
| | - D. J. Jacob
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - R. M. Yantosca
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - M. P. Sulprizio
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - D. B. Millet
- Department of Soil, Water and Climate, University of Minnesota, St. Paul, MN, USA
| | - J. Mao
- Princeton University, GFDL, Princeton, NJ, USA
| | - F. Paulot
- Department of Atmospheric Science, Colorado State University, Fort Collins, CO, USA
| | - H. B. Singh
- NASA Ames Research Center, Moffett Field, CA, USA
| | - A. Roiger
- Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Oberpfaffenhofen, Germany
| | - L. Ries
- Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX, USA
| | - R.W. Talbot
- Federal Environment Agency, GAW Global Station Zugspitze/Hohenpeissenberg, Zugspitze, Germany
| | - K. Dzepina
- Department of Chemistry, Michigan Technological University, Houghton, MI, USA
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Zhang H, Xu X, Lin W, Wang Y. Wintertime peroxyacetyl nitrate (PAN) in the megacity Beijing: role of photochemical and meteorological processes. J Environ Sci (China) 2014; 26:83-96. [PMID: 24649694 DOI: 10.1016/s1001-0742(13)60384-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Previous measurements of peroxyacetyl nitrate (PAN) in Asian megacities were scarce and mainly conducted for relative short periods in summer. Here, we present and analyze the measurements of PAN, O3, NO(x), etc., made at an urban site (CMA) in Beijing from 25 January to 22 March 2010. The hourly concentration of PAN averaged 0.70 x 10(-9) mol/mol (0.23 x 10(-9) -3.51 x 10(-9) mol/mol) and was well correlated with that of NO2 but not O3, indicating that the variations of the winter concentrations of PAN and 03 in urban Beijing are decoupled with each other. Wind conditions and transport of air masses exert very significant impacts on O3, PAN, and other species. Air masses arriving at the site originated either from the boundary layer over the highly polluted N-S-W sector or from the free troposphere over the W-N sector. The descending free-tropospheric air was rich in O3, with an average PAN/O3 ratio smaller than 0.031, while the boundary layer air over the polluted sector contained higher levels of PAN and primary pollutants, with an average PAN/O3 ratio of 0.11. These facts related with transport conditions can well explain the observed PAN-O3 decoupling. Photochemical production is important to PAN in the winter over Beijing. The concentration of the peroxyacetyl (PA) radical was estimated to be in the range of 0.0014 x 10(-12) -0.0042 x 10(-12) mol/mol. The contributions of the formation reaction and thermal decomposition to PAN's variation were calculated and found to be significant even in the colder period in air over Beijing, with the production exceeding the decomposition.
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Lee JB, Yoon JS, Jung K, Eom SW, Chae YZ, Cho SJ, Kim SD, Sohn JR, Kim KH. Peroxyacetyl nitrate (PAN) in the urban atmosphere. CHEMOSPHERE 2013; 93:1796-1803. [PMID: 23838043 DOI: 10.1016/j.chemosphere.2013.06.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Revised: 05/25/2013] [Accepted: 06/04/2013] [Indexed: 06/02/2023]
Abstract
Peroxyacetyl nitrate (PAN) in air has been well known as the indicator of photochemical smog due to its frequent occurrences in Seoul metropolitan area. This study was implemented to assess the distribution characteristics of atmospheric PAN in association with relevant parameters measured concurrently. During a full year period in 2011, PAN was continuously measured at hourly intervals at two monitoring sites, Gwang Jin (GJ) and Gang Seo (GS) in the megacity of Seoul, South Korea. The annual mean concentrations of PAN during the study period were 0.64±0.49 and 0.57±0.46 ppb, respectively. The seasonal trends of PAN generally exhibited dual peaks in both early spring and fall, regardless of sites. Their diurnal trends were fairly comparable to each other. There was a slight time lag (e.g., 1 h) in the peak occurrence pattern between O3 and PAN, as the latter trended to peak after the maximum UV irradiance period (16:00 (GJ) and 17:00 (GS)). The concentrations of PAN generally exhibited strong correlations with particulates. The results of this study suggest that PAN concentrations were affected sensitively by atmospheric stability, the wet deposition of NO2, wind direction, and other factors.
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Affiliation(s)
- Jun-Bok Lee
- Seoul Metropolitan Government Institute of Public Health and Environment, Seoul, Republic of Korea
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7
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A Cryogen-free Refrigerating Prconcentration/Thermal Desorption Instrument for On-line Determination of Volatile Organic Compounds in Ambient Air. CHINESE JOURNAL OF ANALYTICAL CHEMISTRY 2012. [DOI: 10.3724/sp.j.1096.2011.01482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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8
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A Cryogen-free Refrigerating Preconcentration/Thermal Desorption System for On-line Determination of Volatile Organic Compounds in Ambient Air. CHINESE JOURNAL OF ANALYTICAL CHEMISTRY 2011. [DOI: 10.1016/s1872-2040(10)60474-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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9
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Peng H, Wang J, Shen Z, Wu D, Guan Y. A cryogen-free refrigerating preconcentration device for the measurement of C2 to C4 hydrocarbons in ambient air. Analyst 2011; 136:586-90. [DOI: 10.1039/c0an00563k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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10
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Monedero E, Salgado M, Villanueva F, Martín P, Barnes I, Cabañas B. Infrared absorption cross-sections for peroxyacyl nitrates (nPANs). Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.10.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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11
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Bechara J, Borbon A, Jambert C, Perros PE. New off-line aircraft instrumentation for non-methane hydrocarbon measurements. Anal Bioanal Chem 2008; 392:865-76. [PMID: 18751685 DOI: 10.1007/s00216-008-2330-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2008] [Revised: 07/18/2008] [Accepted: 07/31/2008] [Indexed: 12/01/2022]
Abstract
New off-line instrumentation was developed to implement measurements of non-methane hydrocarbons (NMHC) on (French) research aircraft. NMHC are collected on multisorbent tubes by AMOVOC (Airborne Measurements Of Volatile Organic Compounds), a new automatic sampler. AMOVOC is a versatile and portable sampler targeting a wide range of NMHC at high frequency (sampling time of 10 min). Multisorbent tubes are analyzed on the ground by short-path thermal desorption coupled with gas chromatography and mass spectrometry. The development and optimization of both NMHC sampling and analysis are reported here. On the one hand, the paper points out technical choices that were made according to aircraft constraints and avoiding sample loss or contamination. On the other hand, it describes analytical optimization, tube storage stability, and moisture removal. The method shows high selectivity, sensitivity (limit of detection less than 10 ppt) and precision (less than 24%). Finally, NMHC data collected on French aircraft during the African Monsoon Multidisciplinary Analysis campaign are reported for the first time. The results highlight instrumentation validity and protocol efficiency for NMHC measurements in the lower and upper troposphere.
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Affiliation(s)
- Joelle Bechara
- Laboratoire Interuniversitaire des Systèmes Atmosphériques, Universités Paris 12 et Paris 7, CNRS, 94000, Créteil, France.
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12
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Physical processes and real-time chemical measurement of the insect olfactory environment. J Chem Ecol 2008; 34:837-53. [PMID: 18548311 DOI: 10.1007/s10886-008-9490-7] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Revised: 04/10/2008] [Accepted: 04/28/2008] [Indexed: 10/22/2022]
Abstract
Odor-mediated insect navigation in airborne chemical plumes is vital to many ecological interactions, including mate finding, flower nectaring, and host locating (where disease transmission or herbivory may begin). After emission, volatile chemicals become rapidly mixed and diluted through physical processes that create a dynamic olfactory environment. This review examines those physical processes and some of the analytical technologies available to characterize those behavior-inducing chemical signals at temporal scales equivalent to the olfactory processing in insects. In particular, we focus on two areas of research that together may further our understanding of olfactory signal dynamics and its processing and perception by insects. First, measurement of physical atmospheric processes in the field can provide insight into the spatiotemporal dynamics of the odor signal available to insects. Field measurements in turn permit aspects of the physical environment to be simulated in the laboratory, thereby allowing careful investigation into the links between odor signal dynamics and insect behavior. Second, emerging analytical technologies with high recording frequencies and field-friendly inlet systems may offer new opportunities to characterize natural odors at spatiotemporal scales relevant to insect perception and behavior. Characterization of the chemical signal environment allows the determination of when and where olfactory-mediated behaviors may control ecological interactions. Finally, we argue that coupling of these two research areas will foster increased understanding of the physicochemical environment and enable researchers to determine how olfactory environments shape insect behaviors and sensory systems.
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13
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Cook PA, Savage NH, Turquety S, Carver GD, O'Connor FM, Heckel A, Stewart D, Whalley LK, Parker AE, Schlager H, Singh HB, Avery MA, Sachse GW, Brune W, Richter A, Burrows JP, Purvis R, Lewis AC, Reeves CE, Monks PS, Levine JG, Pyle JA. Forest fire plumes over the North Atlantic: p-TOMCAT model simulations with aircraft and satellite measurements from the ITOP/ICARTT campaign. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2006jd007563] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Peter A. Cook
- Centre for Atmospheric Science, Department of Chemistry; University of Cambridge; Cambridge UK
| | - Nicholas H. Savage
- Centre for Atmospheric Science, Department of Chemistry; University of Cambridge; Cambridge UK
- Atmospheric Chemistry Modelling Support Unit, National Environment Research Council Centres for Atmospheric Sciences; University of Cambridge; Cambridge UK
| | - Solène Turquety
- Atmospheric Chemistry Modeling Group; Harvard University; Cambridge Massachusetts USA
| | - Glenn D. Carver
- Centre for Atmospheric Science, Department of Chemistry; University of Cambridge; Cambridge UK
- Atmospheric Chemistry Modelling Support Unit, National Environment Research Council Centres for Atmospheric Sciences; University of Cambridge; Cambridge UK
| | - Fiona M. O'Connor
- Centre for Atmospheric Science, Department of Chemistry; University of Cambridge; Cambridge UK
| | - Andreas Heckel
- Institute of Environmental Physics; University of Bremen; Bremen Germany
| | - David Stewart
- School of Environmental Sciences; University of East Anglia; Norwich UK
| | | | - Alex E. Parker
- Department of Chemistry; University of Leicester; Leicester UK
| | - Hans Schlager
- Institut fuer Physik der Atmosphaere; Deutsches Zentrum fuer Luft- und Raumfahrt; Oberpfaffenhofen Germany
| | | | | | | | - William Brune
- Department of Meteorology; Pennsylvania State University; University Park Pennsylvania USA
| | - Andreas Richter
- Institute of Environmental Physics; University of Bremen; Bremen Germany
| | - John P. Burrows
- Institute of Environmental Physics; University of Bremen; Bremen Germany
| | - Ruth Purvis
- Facility of Airborne Atmospheric Measurements; Cranfield UK
| | | | - Claire E. Reeves
- School of Environmental Sciences; University of East Anglia; Norwich UK
| | - Paul S. Monks
- Department of Chemistry; University of Leicester; Leicester UK
| | - James G. Levine
- Centre for Atmospheric Science, Department of Chemistry; University of Cambridge; Cambridge UK
| | - John A. Pyle
- Centre for Atmospheric Science, Department of Chemistry; University of Cambridge; Cambridge UK
- Atmospheric Chemistry Modelling Support Unit, National Environment Research Council Centres for Atmospheric Sciences; University of Cambridge; Cambridge UK
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Reidy S, George D, Agah M, Sacks R. Temperature-Programmed GC Using Silicon Microfabricated Columns with Integrated Heaters and Temperature Sensors. Anal Chem 2007; 79:2911-7. [PMID: 17311465 DOI: 10.1021/ac062148s] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Columns were fabricated in silicon substrates by deep reactive-ion etching. The channels were sealed with a glass wafer anodically bonded to the silicon surface. Heaters and temperature sensors were fabricated on the back side of each column chip. A microcontroller-based temperature controller was used with a PC for temperature programming. Temperature programming, with channel lengths of 3.0 and 0.25 m, is described. The 3.0-m-long channel was fabricated on a 3.2 cmx3.2 cm chip. Four columns were fabricated on a standard 4-in. silicon wafer. The 0.25-m-long channel was fabricated on a 1.1 cmx1.1 cm chip, and approximately 40 columns could be fabricated on a 4-in. wafer. All columns were coated with a nonpolar poly(dimethylsiloxanes) stationary phase. A static coating procedure was employed. The 3.0-m-long column generated about 12000 theoretical plates, and the 0.25-m-long channel generated about 1000 plates at optimal carrier gas velocity. Linear temperature ramps as high as 1000 degrees C/min when temperature programmed from 30 to 200 degrees C were obtained with the shorter column. With the 0.25-m-long column, normal alkanes from n-C5 through n-C15 were eluted in less than 12 s using a temperature ramp rate of 1000 degrees C/min. Temperature uniformity over the column chip surface was measured with infrared imaging. A variation of about 2 degrees C was obtained for the 3.0-m-long channel. Retention time reproducibility with temperature programming typically ranged from +/-0.15% to +/-1.5%. Design of the columns and the temperature controller are discussed. Performance data are presented for the different columns lengths.
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Affiliation(s)
- Shaelah Reidy
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA.
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15
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Greally BR, Nickless G, Simmonds PG. Retention behaviour of volatile C1–C3 fluoroalkanes upon selected preconcentration adsorbents. J Chromatogr A 2006; 1133:49-57. [PMID: 16939686 DOI: 10.1016/j.chroma.2006.08.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2006] [Revised: 08/10/2006] [Accepted: 08/11/2006] [Indexed: 11/21/2022]
Abstract
The retention behaviour of several gaseous fluorinated greenhouse gases on carbon-based adsorbents is presented. Retention, calculated on the basis of compound breakthrough volume (BTV), is dependent on the molecular composition of the adsorbate, with compounds possessing chlorine or polarizable hydrogens being better retained than those possessing higher fluorine content. Of the adsorbents tested the carbon molecular sieves (CMSs) of highest surface area show greater retention than those with lower area. Retention of fluorocarbons is generally higher on activated charcoals but this adsorbent type can cause irreversible retention, possible degradation and is more difficult to use practically due to its heterogeneous composition. These breakthrough volume results can be used to determine the best combination and quantities of each adsorbent that can be used within a preconcentration device with a view to developing an analytical system for the determination of fluorocarbon gases in low concentration air samples.
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Affiliation(s)
- Brian R Greally
- School of Chemistry, University of Bristol, Cantocks Close, Bristol BS8 1TS, UK.
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16
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Tanner D, Helmig D, Hueber J, Goldan P. Gas chromatography system for the automated, unattended, and cryogen-free monitoring of C2 to C6 non-methane hydrocarbons in the remote troposphere. J Chromatogr A 2006; 1111:76-88. [PMID: 16497314 DOI: 10.1016/j.chroma.2006.01.100] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2005] [Revised: 01/23/2006] [Accepted: 01/24/2006] [Indexed: 11/22/2022]
Abstract
An unattended, automated, on-line, cryogen-free, remotely controlled gas chromatography (GC) system was developed and has been deployed for more than 1 year for the continuous determination of C(2) to C(6) hydrocarbons at an observatory located at 2225 m elevation, on the summit caldera of an inactive volcano on the island of Pico, Azores. The GC instrument is tailored to the measurement challenges at this remote and high altitude site. All consumable gases are prepared in situ. Total power use remains below 700 W at all times. Sample collection and analysis is performed without use of cryogen. Hydrocarbons are concentrated on a one-stage trapping/injection system consisting of a Peltier-cooled multi-bed solid adsorbent trap. Analytes are detected after thermal desorption and separation on an alumina-PLOT (porous-layer open tubular) column by flame ionization detection (FID). Sample focusing, desorption, separation and detection parameters were thoroughly investigated to ensure quantitative collection and subsequent injection onto the GC system. GC operation is controlled remotely and data are downloaded daily. Sample volumes (600 and 3000 ml) are alternated for analysis of C(2) to C(3) and C(3) to C(6) hydrocarbons, respectively. Detection limits are in the low parts per trillion by volume (pptv) range, sufficient for quantification of the compounds of interest at their central North Atlantic lower free troposphere background concentrations.
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Affiliation(s)
- David Tanner
- Institute of Arctic and Alpine Research, University of Colorado at Boulder, 80309-0450, USA
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17
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Hopkins JR, Boddy RK, Hamilton JF, Lee JD, Lewis AC, Purvis RM, Watson NJ. An observational case study of ozone and precursors inflow to South East England during an anticyclone. ACTA ACUST UNITED AC 2006; 8:1195-202. [PMID: 17133276 DOI: 10.1039/b608062f] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Summertime photochemical air pollution episodes within the United Kingdom have been proposed via modelling studies to be strongly influenced by regional scale inflow of air from the continental European boundary layer. We present a vertically resolved case study using measurements made from the NERC/Met Office BAe 146 research aircraft on 18th August 2005 over the South East of England and the North Sea during a weak anticyclone centred over Northern Europe. The vertical distribution of ozone, CO, NO(x), peroxyacetyl nitrate (PAN) and a wide range of both nonmethane hydrocarbons (NMHC) and oxygenated volatile organic compounds (OVOCs) were determined between 500 ft (approximately 152 m) and 7000 ft (approximately 2134 m) over the East Anglia coastline and 50 km inland. In excess of 80 ppbV ozone was observed within inflowing boundary layer air over the North Sea coast in a broad N-S sloping feature around 60 km wide. The inflowing feature of European origin was also observed further inland within the boundary layer albeit with lower, more variable, ozone mixing ratios. The increased variability in ozone over land was a product of titration by fresh surface emissions of NO via rapid upward transport in thermals, a hypothesis supported by the observed vertical wind speed component. Fast boundary layer mixing over land was further illustrated by a uniform distribution in reactive alkenes. A comparison between aircraft and surface O(3) UK AUN (Automatic Urban Network) measurements showed good agreement with the inland site, Sibton, but marked differences with the coastal monitoring site at Weybourne, potentially due to gradients established by ocean deposition in stably stratified marine air.
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Affiliation(s)
- J R Hopkins
- Department of Chemistry, University of York, York, UK.
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18
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Lambertus G, Sacks R. Stop-Flow Programmable Selectivity with a Dual-Column Ensemble of Microfabricated Etched Silicon Columns and Air as Carrier Gas. Anal Chem 2005; 77:2078-84. [PMID: 15801741 DOI: 10.1021/ac040174p] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A series-coupled ensemble of microfabricated GC columns made by dry reactive ion etching of silicon substrates is evaluated for use with pneumatic selectivity enhancement techniques for targeted pairs of volatile organic compounds. Each column is 3.0 m long with a 150 miceom wide by 240 microm deep cross section. Dynamic coating was used to prepare a nonpolar column with a dimethyl polysiloxane stationary phase and a moderately polar column with a trifluoropropylmethyl polysiloxane stationary phase. Each column generates 5000-6000 theoretical plates. The columns are operated in series with the nonpolar column connected to a split inlet, the polar column connected to a flame ionization detector, and a valve connected between the column junction point and the inlet to the first column. When the valve is closed, the effluent from the first column passes directly into the second column. When the valve is open, both ends of the first column are at the inlet pressure, and flow stops in this column while increased flow is obtained in the second column. For analyte pairs that are separated by the first column but coelute from the column ensemble, the valve is opened for a few seconds after the first component of the pair has passed into the second column but the second component is still in the first column. The result is enhanced separation of the pair in the ensemble chromatogram. Relatively thick cross-linked stationary-phase films are used to increase retention for volatile compounds. The combination of air carrier gas and stationary-phase film thickness in the range 1-2 microm requires the use of relatively low average carrier gas velocities (typically less than 10 cm/s) for adequate resolving power of the column ensemble. Selectivity enhancement under isothermal conditions for a 14-component mixture of volatile organic compounds is demonstrated where neither of the columns alone nor the column ensemble without selectivity enhancement could obtain a complete separation.
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Affiliation(s)
- Gordon Lambertus
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
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Schubert JK, Miekisch W, Geiger K, Nöldge-Schomburg GFE. Breath analysis in critically ill patients: potential and limitations. Expert Rev Mol Diagn 2004; 4:619-29. [PMID: 15347256 DOI: 10.1586/14737159.4.5.619] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Breath tests are attractive since they are noninvasive and can be repeated frequently in the dynamically changing state of critically ill patients. Volatile organic compounds can be produced anywhere in the body and are transported via the bloodstream and exhaled through the lung. They can reflect physiologic or pathologic biochemical processes such as lipid peroxidation, liver disease, renal failure, allograft rejection, and dextrose or cholesterol metabolism. This review describes the diagnostic potential of endogenous organic volatile substances in the breath of critically ill patients. Since many of these patients require ventilatory support, aspects of breath analysis under mechanical ventilation will be addressed. Analytical procedures, problems concerning the physiologic meaning of breath markers and future developments will be discussed.
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Affiliation(s)
- Jochen K Schubert
- Department of Anaesthesiology and Intensive Care, University of Rostock, Schillingallee 35, 18057 Rostock, Germany.
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