Variables & measurement techniques

CiGas operates and supports instrumentation and observations collected of the following atmospheric reactive trace gases:

1. non-Methane Hydrocarbons (NMHCs),
2. Oxygenated VOCs (OVOCs), 
3. Condensing vapours and direct aerosol precursors , and
4. Nitrogen Oxides (NOx).

Data have to be reported in amount fractions (e.g. nmol/mol) in accordance with the measurement guidelines and the specifications set by the National Metrology Institutes.

 

 

Non-Methane Hydrocarbons

NMHCs are typically over 40 compounds subclassified into anthropogenic and biogenic.

Currently the following NMHCs can be traced back to certified standards obtained from the central calibration laboratory NPL:

Aliphatics (mostly anthropogenic)

Ethane	Ethene
Ethyne	Propane
Propene	n-Butane
2-Methylpropane	trans-But-2-ene
cis-But-2-ene	But-1-ene
1,3-Butadiene	Isoprene
2-Methylbutane	n-Pentane
trans-Pent-2-ene	Pent-1-ene
2-Methylpentane	n-Hexane
n-Heptane	n-Octane
2,2,4-Trimethylpentane

Aromatics (anthropogenic)

Benzene	Toluene
Ethylbenzene	m-Xylene
p-Xylene	o-Xylene
1,3,5-Trimethylbenzene	1,2,4-Trimethylbenzene
1,2,3-Trimethylbenzene

Monoterpenes (mostly biogenic)

(+/-)-α-Pinene	(+)-3-Carene
R-(+)-Limonene	1,8-Cineole

Currently CiGas-supported measurement techniques for NMHCs:

• GC-FID

• GC-MS

• PTR-MS

• PTR-TOF-MS

Oxygenated VOCs

Aldehydes, ketones, alcohols (e.g. methanol, formaldehyde, acetaldehyde, acetone)

Currently CiGas-supported measurement techniques for OVOCs:

• GC-FID

• GC-MS

• PTR-MS

• PTR-TOF-MS

• DNPH-HPLC

 

Condensing vapours

Condensing vapours and direct aerosol precursors such as sulfuric acid and Highly Oxygenated Molecules (HOM; e.g. C₁₀H₁₄O₉)

The definition of the term HOM is described in Chemical Review “Highly Oxygenated Organic Molecules (HOM) from Gas-Phase Autoxidation Involving Peroxy Radicals: A Key Contributor to Atmospheric Aerosol” https://pubs.acs.org/doi/10.1021/acs.chemrev.8b00395

Currently CiGas-supported measurement techniques for Condensables:

• CI-APi-TOF

Aldehydes, ketones, alcohols (e.g. methanol, formaldehyde, acetaldehyde, acetone)

Currently CiGas-supported measurement techniques for OVOCs:

• GC-FID

• GC-MS

• PTR-MS

• PTR-TOF-MS

• DNPH-HPLC

•  

Nitrogen Oxides

Nitrogen oxides (NOx): Nitric oxide (NO) and nitrogen dioxide (NO₂) 

• Chemiluminescence technique for detection of NO

• Photolytic conversion (PLC) for detection of NO₂

•  

Recent achievements

To be added

Publications & documents

Standard Operation Procedures

For NOx and VOC can be found here SOP for NOx and VOC (VOC: 2nd part of the document starting at page 24)

References

VOCs

Apel, E.C. et al. (1998): Measurements comparison of oxygenated volatile organic compounds at a rural site during the 1995 SOS Nashville Intensive. Journal of Geophysical Research 103 (D17): 22,295 – 22,316.

Apel, E.C., Hills, A. J., Lueb, R., Zindel, S., Eisele, S., and Riemer, D. D. (2003): A fast-GC/MS system to measure C₂ to C₄ carbonyls and methanol aboard aircraft. Journal of Geophysical Research 108, 8794, doi:10.1029/2002jd003199, 2003.

Apel, E.C. et al. (2008): Intercomparison of oxygenated volatile organic compound measurements at the SAPHIR atmosphere simulation chamber. Journal of Geophysical Research 113 (D20307).

Baars, B. and Schaller, H. (1994), Fehlersuche in der Gaschromatografie, VHC Verlagsgesellschaft mbH.

Barkley, C.S. et al. (2005): Development of a Cryogen-Free Concentration System for Measurements of Volatile Organic Compounds. Analytical Chemistry 77 (21): 6989-6998.

Blanchard et al. (2017): Atmospheric Isoprene in the NOAA/INSTAAR Global Greenhouse Gas Reference Network. Presentation at the GAW VOC expert meeting, Boulder, May 2017.

Blake, R. S., Monks, P. S., Ellis, A. M. (2009): Proton‐Transfer Reaction Mass Spectrometr. Chem. Rev. 109: 861‐896.

Convention on Long-range Transboundary Air Pollution (CLRTAP) (2016), United National Economic and Social Council (UNESC) Gothenburg Protocol: Guidelines for estimation and measurement of emissions of volatile organic compounds, http://www.unece.org/environmental-policy/conventions/envlrtapwelcome/guidance-documents-and-other-methodological-materials/gothenburg-protocol.html, accessed Nov 2018.

Currie LA (1995) Nomenclature and evaluation of analytical methods, including quantification and detection capabilities. Pure Appl. Chem. 1995; 67(10) 1699-1723

De Gouw, J., Warneke, C. (2007): Measurements of volatile organic compounds in the earth’s atmosphere using proton-transfer-reaction mass spectrometry. Mass Spectrom. Rev. 26 (2): 223–257.

Dietz W.A. (1967): Response factors for gas chromatographic analyses, J. of Gas Chromatography 5, 68.

Englert, J., Claude, A., Demichelis, A., Persijn, S., Baldan, A., Li, J., Plass-Duelmer, C., Michl, K., Tensing, E., Wortman, R., Ghorafi,Y., Lecuna, M., Sassi, G., Sassi, M.P., and D. Kubistin (2018): Preparation and analysis of zero gases for the measurement of trace VOCs in air monitoring. Atmos. Meas. Tech., 11, 3197-3203, https://doi.org/10.5194/amt-11-3197-2018.

Environmental Protection Agency (EPA) (2016): Ambient Monitoring Technology Information Center (AMTIC): Photochemical Assessment Monitoring Stations (PAMS), https://www3.epa.gov/ttnamti1/pamsmain.html, accessed Nov 2018.

European Monitoring and Evaluation Programme (EMEP) (2008), Directive 2008/50/EC on ambient air quality and cleaner air for Europe, https://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2008:152:0001:0044:EN:PDF, accessed Nov 2018.

Folkers, A. (2002): Oxygenated volatile organic compounds in the troposphere: Development and employment of a gas chromatographic detection method. Report of the Research Centre Jülich 3998. Dissertation University of Köln, Jülich.

Goldan, P.D., Kuster, W.C. (2004): Nonmethane hydrocarbon and oxy hydrocarbon measurements during the 2002 New England Air Quality Study. Journal of Geophysical Research 109 (D21309).

Goldstein, A.H., Schade, G.W. (2000): Quantifying biogenic and anthropogenic contributions to acetone mixing ratios in a rural environment. Atmospheric Environment 34: 4997-5006.

Graus, M., Müller, M., Hansel, A. (2010): High Resolution PTR-TOF: Quantification and Formula Confirmation of VOCS in Real Time. J. Am. Soc. Mass Spectrom. 21 (6): 1037–1044.

Greenberg, J.P., Zimmermann, P.R., Pollock, W.F., Lueb, R.A., Heidt, L.E. (1992): Diurnal variability of atmospheric methane, nonmethane hydrocarbons, and carbon monoxide at Mauna Loa. Journal of Geophysical Research 97: 10,395-10,413.

Hellén, H., P. Kuronen, and H. Hakola (2012): Heated stainless stell tube for ozone removal in the ambient air measurements of mono- and sesquiterpenes. Atmospheric Environment 57: 35-40, DOI:10.1016/j.atmosenv.2012.04.019.

Helmig, D., Greenberg, J.P. (1994): Automated in situ gas chromatographic-mass spectrometric analysis of ppt level volatile organic trace gases using multistage solid-adsorbent trapping. Journal of Chromatography A 677: 123-132.

Helmig D. and Greenberg J. (1995) Artifact formation from the use of potassium iodide (KI) based ozone traps in atmospheric sampling. J. High Res. Chrom. 18, 15-18.

Helmig, D. (1997): Ozone removal techniques in the sampling of atmospheric volatile organic trace gases. Atmospheric Environment 31 (21): 3635-3651.

Helmig, D. (1999): Air analysis by gas chromatography. Journal of Chromatography A 843(1-2): 129-146.

Helmig, D., J. Bottenheim, I. E. Galbally, A. Lewis, M. J. T. Milton, S. Penkett, C. Plass‐Duelmer, S. Reimann, P. Tans, and S. Thiel (2009): Volatile Organic Compounds in the Global Atmosphere, Eos Trans. AGU, 90(52): 513–514.

Hoerger, C. C., A. Claude, C. Plass-Duelmer, S. Reimann, E. Eckart, R. Steinbrecher, J. Aalto, J. Arduini, N. Bonnaire, J. N. Cape, A. Colomb, R. Connolly, J. Diskova, P. Dumitrean, C. Ehlers, V. Gros, H. Hakola, M. Hill, J. R. Hopkins, J. Jäger, R. Junek, M. K. Kajos, D. Klemp, M. Leuchner, A. C. Lewis, N. Locoge, M. Maione, D. Martin, K. Michl, E. Nemitz, S. O’Doherty, P. Pérez Ballesta, T. M. Ruuskanen, S. Sauvage, N. Schmidbauer, T. G. Spain, E. Straube, M. Vana, M. K. Vollmer, R. Wegener, and A. Wenger (2015), ACTRIS none-methane hydrocarbon intercomparison experiment in Europe to support WMO GAW and EMEP observation networks. Atmos. Meas. Tech. 8, 2715-2736, DOI:10.5194/amt-8-2715-2015.

Maione, D. Martin, K. Michl, E. Nemitz, S. O’Doherty, P. Pérez Ballesta, T. M. Ruuskanen, S. Sauvage, N. Schmidbauer, T. G. Spain, E. Straube, M. Vana, M. K. Vollmer, R. Wegener, and A. Wenger (2015), ACTRIS none-methane hydrocarbon intercomparison experiment in Europe to support WMO GAW and EMEP observation networks. Atmos. Meas. Tech. 8, 2715-2736, DOI:10.5194/amt-8-2715-2015.

Hopkins J.R., Lewis A.C., Read K.A. (2003): A two-column method for long-term monitoring of non-methane hydrocarbons (NMHCs) and oxygenated volatile organic compounds (o-VOCs). Journal of Environmental Monitoring, 5(1).

Hopkins, J.R., Jones, C.E., Lewis, A.C. (2011): A dual channel gas chromatograph for atmospheric analysis of volatile organic compounds including oxygenated and monoterpene compounds. Journal of Environmental Monitoring DOI: 10.1039/c1em10050e.

Joint Committee for Guides in Metrology (JCGM) (2008): Evaluation of measurement data: Guide to the expression of uncertainty in measurement, https://www.bipm.org/utils/common/documents/jcgm/JCGM_100_2008_E.pdf, accessed Nov 2018.

Komenda, M., Schaub, A., Koppmann, R., 2003. Description and characterization of an on-line system for long-term measurements of isoprene, methyl vinyl ketone, and methacrolein in ambient air. Journal of Chromatography A 995, 185-201.

Koppmann, R., Johnen, F.J., Khedim, A., Rudolph, J., Wedel, A., Wiards, B. (1995): The influence of ozone on light nonmethane hydrocarbons during cryogenic preconcentration. Journal of Geophysical Research 100: 11,383-11,391.

Kuster, W.C, Goldan, P.D., Albritton, D.L. (1986): Ozone interferences with ambient dimethyl sulfide measurements: The problem and a solution. Eos 67: 887.

Lamanna, M.S., Goldstein, A.H. (1999): In situ measurements of C₂-C₁₀ volatile organic compounds above a Sierra Nevada ponderosa pine plantation. Journal of Geophysical Research 104 (D17): 21,247-21,262.

Legreid, G. (2006): Oxygenated volatile organic compounds (OVOCs) in Switzerland: From the boundary layer to the unpolluted troposphere. Dissertation ETH No. 16982, Zürich, Dübendorf.

Lee, J.H., Batterman, S.A., Jia, C., Chernyak, S. (2006): Ozone artifacts and carbonyl measurements using Tenax GR, Tenax TA, Carbopack B, and Carbopack X adsorbents. Journal Air & Waste Management Association 56: 1503-1517.

Leibrock, E. (1996): Development of a gas chromatography system for trace analysis of oxygenated volatile organic compounds in air. Scientific journal 40, Fraunhofer-Institute for Atmospheric Environmental Research, Garmisch-Partenkirchen. Dissertation Hamburg University of Technology, Hamburg-Harburg.

Leibrock, E., Slemr, J. (1997): Method for measurement of volatile oxygenated hydrocarbons in ambient air. Atmospheric Environment 31 (20): 3329-3339.

Lewis, A.C. et al. (1995): Programmed temperature vaporization injection (PTV) for in situ field measurements of isoprene, and selected oxidation products in a eucalyptus forest. Atmospheric Environment 29 (15): 1871-1875.

Lindinger, W., A. Hansel., and A. Jordan (1998): Proton‐transfer‐reaction mass spectrometry (PTR‐MS): On‐line monitoring of volatile organic compounds at pptv levels, Chem. Soc. Rev., 27, 347–354.

McClenny W.A., Pleil J.D., Evans G.F., Oliver K.D., Holdren M.W., Winberry W.T. (1991): Canister-based method for monitoring toxic VOCs in ambient air. J. Air Waste Man. Assn., 41, 1308–1318.

Miller, B.R., Weiss, R.F., Salameh, P.K., Tanhua, T., Greally, B.R., Mühle, J., Simmonds P.G. (2008) Medusa: A sample preconcentration and GC/MS detector system for in situ measurements of atmospheric trace halocarbons, hydrocarbons, and sulfur compounds, Anal. Chem., 80 (5), 1536-1545.

Palluau F., Ph Mirabel , M Millet (2007): Influence of ozone on the sampling and storage of volatile organic compounds in canisters, Environ Chem. Lett. 5, 51–55.

Plass-Dülmer, C., Michl, K., Ruf, R., Berresheim, H. (2002), C₂ - C₈ hydrocarbon measurement and quality control procedures at the Global Atmosphere Watch Observatory Hohenpeissenberg. J. Chromatogr. 953, 175-197.

Plass-Dülmer C., N. Schmidbauer J. Slemr, F. Slemr, H. D'Souza (2006): European hydrocarbon intercomparison experiment AMOHA part 4: Canister sampling of ambient air, J. Geophys. Res., 111, D04306, doi:10.1029/2005JD006351.

Pollmann J., Ortega J., and Helmig D. (2005) Analysis of atmospheric sesquiterpenes: sampling losses and mitigation of ozone interferences. Environ. Sci. and Technol. 39, 9620-9629.

Pollmann J., Helmig D., Hueber J., Tanner D., and Tans P. (2006) Evaluation of adsorbent materials for cryogen-free trapping-one stage-GC analysis of atmospheric C₂-C₆ non-methane hydrocarbons. J. Chrom., 1134, 1-15.

Pollmann J., D. Helmig, J. Hueber, Ch. Plass-Dülmer, P. Tans (2008): Sampling, storage, and analysis of C₂–C₇ non-methane hydrocarbons from the US National Oceanic and Atmospheric Administration Cooperative Air Sampling Network glass flasks, J. Chromatogr., A 1188, 75-87.

Riemer, D. et al. (1998): Observations of nonmethane hydrocarbons and oxygenated volatile organic compounds at a rural site in the southeastern United States. Journal of Geophysical Research 103 (21): 28,111 – 28,128.

Roukos, J. et al. (2009): Development and validation of an automated monitoring system for oxygenated volatile organic compounds and nitrile compounds in ambient air. Journal of Chromatography A 1216: 8642-8651.

Sternberg J.C., W.S. Gallaway and D.T.L. Jones, in N. Brenner (1962), The mechanism of response of Flame Ionization Detectors, in J. Callen and M.D. Weiss (Editors) Gas-Chromatography, Academic Press, New York, p. 231-267.

Taipale, R., Ruuskanen, T. M., Rinne, J., Kajos, M. K., Hakola, H., Pohja, T., Kulmala, M. (2008): Technical Note: Quantitative long-term measurements of VOCS concentrations by PTR-MS – measurement, calibration, and volume mixing ratio calculation methods. Atmospheric Chemistry and Physics 8, 9435-9475.

US-EPA (1998): Technical assistance document for analysis of ozone precursors, US-Environmental Protection Agency, EPA/600-R-98/161.

US-EPA TO-14A (1999): Compendium of methods for the determination of toxic organic compounds in ambient air: determination of volatile organic compounds (VOCs) in ambient air using specially prepared canisters with subsequent analysis by gas chromatography, US-Environmental Protection Agency, Method TO-14A, 2nd ed., EPA/625/R-96/010b.

Wisthaler, A. et al. (2006): Recent developments in proton-transfer-reaction mass spectrometry. Photonic, Electronic and Atomic Collisions, 24th International Conference on Photonic, Electronic and Atomic Collisions, Rosario, Argentina: 462-469. Doi: 10.1142/9789812772442_0060.

WMO (1995), WMO-BMBF Workshop on VOCs - Establishment of a “World Calibration/Instrument Intercomparison Facility for VOCs“ to serve the WMO Global Atmosphere Watch (GAW) Programme, WMO Report, 111.

WMO (2001): Strategy for the Implementation of the Global Atmosphere Watch Programme (2001 – 2007), GAW Report No. 142 (WMO TD No. 1077), 62 pp., World Meteorological Organization, Geneva, Switzerland.

WMO (2001b): Global atmosphere watch measurements guide, GAW Report No. 143 (WMO TD No. 1073), 87 pp., World Meteorological Organization, Geneva, Switzerland.

WMO (2004), IGACO The Integrated Global Atmospheric Chemistry Observations (IGACO) Report of IGOSWMO- ESA, GAW Report #159, 53 pp., World Meteorological Organization, Geneva, Switzerland.

WMO (2007a): A WMO/GAW Expert Workshop on Global Long-Term Measurements of Volatile Organic Compounds, Geneva, Switzerland.

WMO (2007b): GAW Report 172: WMO Global Atmosphere Watch (GAW) Strategic Plan: 2008-2015, Geneva, Switzerland.

WMO (2009): GAW Report 188: Revision of the World Data Centre for Greenhouse Gases Data Submission and Dissemination Guide, Geneva, Switzerland.

WMO (2012): GAW Report 204: Standard Operating Procedures (SOPs) for Air Sampling in Stainless Steel Canisters for Non-Methane Hydrocarbons Analysis (prepared by R. Steinbrecher and E. Weiss), 28 pp., Geneva, Switzerland.

WMO (2017a): Reactive Gases Bulletin No.1, Highlights from the Global Atmosphere Watch Programme, April 2017.

WMO (2017b): WMO Global Atmosphere Watch (GAW) Implementation Plan: 2016-2023.

Zhao, J. and R. Zhang (2004): Proton transfer reaction rate constants between hydronium ion (H₃O+) and volatile organic compounds. Atmospheric Environment, 38, 2177–2185.

Condensables

Bianchi, F. et al. (2019): Highly Oxygenated Organic Molecules (HOM) from Gas-Phase Autoxidation Involving Peroxy Radicals: A Key Contributor to Atmospheric Aerosol. Chem. Rev., 119, 6, 3472–3509, https://doi.org/10.1021/acs.chemrev.8b00395

Eisele, F. L. and Tanner, D. J. (1993): Measurement of the gas phase concentration of H₂SO₄ and methane sulfonic acid and estimates of H₂SO₄ production and loss in the atmosphere, J. Geophys. Res.-Atmos., 98, 9001–9010, https://doi.org/10.1029/93JD00031.

Jokinen, T., Sipilä, M., Junninen, H., Ehn, M., Lönn, G., Hakala, J., Petäjä, T., Mauldin III, R. L., Kulmala, M., and Worsnop, D. R. (2012): Atmospheric sulphuric acid and neutral cluster measurements using CI-APi-TOF, Atmos. Chem. Phys., 12, 4117–4125, https://doi.org/10.5194/acp-12-4117-2012.

Kulmala, M., Petäjä, T., Ehn, M., Thornton, J., Sipilä, M., Worsnop, D.R. and Kerminen, V.-M. (2014): Chemistry of Atmospheric Nucleation: On the Recent Advances on Precursor Characterization and Atmospheric Cluster Composition in Connection with Atmospheric New Particle Formation Annu. Rev. Phys. Chem., 65, 21-37, https://doi.org/10.1146/annurev-physchem-040412-110014.

Rissanen, M. P., Mikkilä, J., Iyer, S., and Hakala, J.(2019): Multi-scheme chemical ionization inlet (MION) for fast switching of reagent ion chemistry in atmospheric pressure chemical ionization mass spectrometry (CIMS) applications, Atmos. Meas. Tech., 12, 6635–6646, https://doi.org/10.5194/amt-12-6635-2019.

 

NOx      

Andersen, S. T., Carpenter, L. J., Nelson, B. S., Neves, L., Read, K. A., Reed, C., Ward, M., Rowlinson, M. J., and Lee, J. D.: Long-term NOx measurements in the remote marine tropical troposphere, Atmospheric Measurement Techniques, 14, 3071-3085, https://doi.org/10.5194/amt-14-3071-2021, 2021.

Fehsenfeld, F. C., Dickerson, R. R., Hübler, G., Luke, W. T., Nunnermacker, L. J., Williams, E. J., Roberts, J. M., Calvert, J. G., Curran, C. M., Delany, A. C., Eubank, C. S., Fahey, D. W., Fried, A., Gandrud, B. W., Langford, A. O., Murphy, P. C., Norton, R. B., Pickering, K. E., and Ridley, B. A.: A ground-based intercomparison of NO, NOx, and NOy measurement techniques, Journal of Geophysical Research: Atmospheres, 92, 14710-14722, 1987.

Fontijn, A., Sabadell, A. J., and Ronco, R. J.: Homogeneous chemiluminescent measurement of nitric oxide with ozone. Implications for continuous selective monitoring of gaseous air pollutants, Analytical Chemistry, 42, 575-579, https://doi.org/10.1021/ac60288a034, 1970.

Fuchs, H., Ball, S. M., Bohn, B., Brauers, T., Cohen, R. C., Dorn, H. P., Dubé, W. P., Fry, J. L., Häseler, R., Heitmann, U., Jones, R. L., Kleffmann, J., Mentel, T. F., Müsgen, P., Rohrer, F., Rollins, A. W., Ruth, A. A., Kiendler-Scharr, A., Schlosser, E., Shillings, A. J. L., Tillmann, R., Varma, R. M., Venables, D. S., Villena Tapia, G., Wahner, A., Wegener, R., Wooldridge, P. J., and Brown, S. S.: Intercomparison of measurements of NO2 concentrations in the atmosphere simulation chamber SAPHIR during the NO3Comp campaign, Atmos. Meas. Tech., 3, 21-37, https://doi.org/10.5194/amt-3-21-2010,  2010.

Gherman, T., Venables, D. S., Vaughan, S., Orphal, J., and Ruth, A. A.: Incoherent Broadband Cavity-Enhanced Absorption Spectroscopy in the near-Ultraviolet: Application to HONO and NO₂, Environmental Science & Technology, 42, 890-895, https://doi.org/10.1021/es0716913, 2008.

Horbanski, M., Pöhler, D., Lampel, J., and Platt, U.: The ICAD (iterative cavity-enhanced DOAS) method, Atmospheric Measurement Techniques, 12, 3365-3381, https://doi.org/10.5194/amt-12-3365-2019, 2019.

Kebabian, P. L., Wood, E. C., Herndon, S. C., and Freedman, A.: A Practical Alternative to Chemiluminescence-Based Detection of Nitrogen Dioxide: Cavity Attenuated Phase Shift Spectroscopy, Environmental Science & Technology, 42, 6040-6045, https://doi.org/10.1021/es703204j, 2008.

Platt, U., Meinen, J., Pöhler, D., and Leisner, T.: Broadband Cavity Enhanced Differential Optical Absorption Spectroscopy (CE-DOAS) - applicability and corrections, Atmospheric Measurement Techniques, 2, 713-723, https://doi.org/10.5194/amt-2-713-2009, 2009.

Reed, C., Evans, M. J., Di Carlo, P., Lee, J. D., and Carpenter, L. J.: Interferences in photolytic NO₂ measurements: explanation for an apparent missing oxidant?, Atmospheric Chemistry and Physics, 16, 4707-4724, https://doi.org/10.5194/acp-16-4707-2016, 2016.

Reimann, S., Wegener, R., Claude, A., Sauvage S.: ACTRIS Updated Measurement Guideline for NOx and VOCs, 2018.

https://www.actris.eu/sites/default/files/inline-files/WP3_D3.17_M42_0.pdf

Sauer, C. G., Pisano, J. T., and Fitz, D. R.: Tunable diode laser absorption spectrometer measurements of ambient nitrogen dioxide, nitric acid, formaldehyde, and hydrogen peroxide in Parlier, California, Atmospheric Environment, 37, 1583-1591, https://doi.org/10.1016/S1352-2310(03)00004-9, 2003.

Sobanski, N., Tuzson, B., Scheidegger, P., Looser, H., Kupferschmid, A., Iturrate, M., Pascale, C., Hüglin, C., and Emmenegger, L.: Advances in High-Precision NO₂ Measurement by Quantum Cascade Laser Absorption Spectroscopy, Applied Sciences, 11, https://doi.org/10.3390/app11031222, 2021.

Tuzson, B., Zeyer, K., Steinbacher, M., McManus, J. B., Nelson, D. D., Zahniser, M. S., and Emmenegger, L.: Selective measurements of NO, NO₂ and NOy in the free troposphere using quantum cascade laser spectroscopy, Atmospheric Measurement Techniques, 6, 927-936, https://doi.org/10.5194/amt-6-927-2013, 2013.

Thornton, J. A., Wooldridge, P. J., and Cohen, R. C.: Atmospheric NO₂:  In Situ Laser-Induced Fluorescence Detection at Parts per Trillion Mixing Ratios, Analytical Chemistry, 72, 528-539, https://doi.org/10.1021/ac9908905, 2000.

Villena, G., Bejan, I., Kurtenbach, R., Wiesen, P., and Kleffmann, J.: Interferences of commercial NO₂ instruments in the urban atmosphere and in a smog chamber, Atmospheric Measurement Techniques, 5, 149-159, https://doi.org/10.5194/amt-5-149-2012, 2012.