Elemental carbon (also known as black carbon) is emitted during the combustion of fossil fuels as small, sooty particles often with other chemicals attached to their surface. Sources of organic carbon include traffic, industrial combustion and the degradation of carbon-containing materials. 

NPL's particle speciation facilities include a Sunset Laboratories Carbon Aerosol Analysis Instrument, which measures the organic and elemental carbon content of particulate matter that has been sampled onto quartz filters following recognised standard methods.

The particulate matter is desorbed from the quartz filter in an oven at temperatures ramping up to 870ºC. Manganese oxide is used to oxidise the soot and organic compounds to carbon dioxide (CO₂) and this is then mixed with hydrogen in the presence of a nickel catalyst, which converts the carbon dioxide to methane (CH₄). The methane is analysed by a flame ionisation detector (FID). Optical methods are used to correct for organic material that is converted to elemental carbon during the heating process.

These graphs show example data from Marylebone Road in London.

This work was funded by the Department of the Environment, Food and Rural Affairs (Defra). NPL also operates four automatic OC/EC instruments on behalf of Defra, as part of the UK's Airborne Particulate Concentrations and Numbers monitoring network.

NPL can offer an OC/EC analysis of small numbers of sampled filters, extended field sampling and analysis, consultancy, and many other related services.

For further information, please contact us.