Thermal-optical analysis for the measurement of elemental carbon (EC) and organic carbon (OC) in ambient air a literature review
A. Karanasiou1, M. C. Minguillón1, M. Viana1, A. Alastuey1, J.-P. Putaud2, W. Maenhaut3, P. Panteliadis4, G. Močnik5, O. Favez6, and T. A. J. Kuhlbusch71Institute of Environmental Assessment and Water Research (IDAEA), Spanish Research Council (CSIC), Barcelona, Spain 2European Commission, Joint Research Centre, Institute of Environment and Sustainability, via E. Fermi, 2749, 21027 Ispra, Italy 3Department of Analytical Chemistry, Ghent University, Gent, 9000, Belgium 4GGD, Department of Air Quality, Public Health Service Amsterdam, 1018WT, the Netherlands 5Aerosol d.o.o., Ljubljana, Slovenia 6Institut National de l'Environnement Industriel et des Risques, Parc Technologique ALATA, 60550 Verneuil-en-Halatte, France 7Institute of Energy and Environmental Technology e.V. (IUTA), Bliersheimerstraße 58–60, 47229 Duisburg, Germany
Received: 22 Jul 2015 – Accepted for review: 20 Aug 2015 – Discussion started: 16 Sep 2015
Abstract. Thermal-optical analysis is currently under consideration by the European standardization body (CEN) as the reference method to quantitatively determine organic carbon (OC) and elemental carbon (EC) in ambient air. This paper presents an overview of the critical parameters related to the thermal-optical analysis including thermal protocols, critical factors and interferences of the methods examined, method inter-comparisons, inter-laboratory exercises, biases and artifacts, and reference materials. The most commonly used thermal protocols include NIOSH-like, IMPROVE_A and EUSAAR_2 protocols either with light transmittance or reflectance correction for charring. All thermal evolution protocols are comparable for total carbon (TC) concentrations but the results vary significantly concerning OC and especially EC concentrations. Thermal protocols with a rather low peak temperature in the inert mode like IMPROVE_A and EUSAAR_2 tend to classify more carbon as EC compared to NIOSH-like protocols, while charring correction based on transmittance usually leads to smaller EC values compared to reflectance. The difference between reflectance and transmittance correction tends to be larger than the difference between different thermal protocols. Nevertheless, thermal protocols seem to correlate better when reflectance is used as charring correction method. The difference between EC values as determined by the different protocols is not only dependent on the optical pyrolysis correction method, but also on the chemical properties of the samples due to different contributions from various sources. The overall conclusion from this literature review is that it is not possible to identify the "best" thermal-optical protocol based on literature data only, although differences attributed to the methods have been quantified when possible.
Karanasiou, A., Minguillón, M. C., Viana, M., Alastuey, A., Putaud, J.-P., Maenhaut, W., Panteliadis, P., Močnik, G., Favez, O., and Kuhlbusch, T. A. J.: Thermal-optical analysis for the measurement of elemental carbon (EC) and organic carbon (OC) in ambient air a literature review, Atmos. Meas. Tech. Discuss., 8, 9649-9712, doi:10.5194/amtd-8-9649-2015, 2015.