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.


VOC Canisters and Gas Chromatograph
Gas Chromatograph and Samling Canisters


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
Aromatics (anthropogenic)
Benzene Toluene
Ethylbenzene m-Xylene
p-Xylene o-Xylene
1,3,5-Trimethylbenzene 1,2,4-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


Oxygenated VOCs

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

Currently CiGas-supported measurement techniques for OVOCs:

  • GC-FID

  • GC-MS

  • PTR-MS




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”

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




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)



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