Atmospheric Environment 38 (2004) 6507–6519 INTERCOMP2000: the comparability of methods in use in Europe for measuring the carbon content of aerosol Harry ten Brink a,Ã , Willy Maenhaut b , Regina Hitzenberger c , Thomas Gnauk d , Gerald Spindler e , Arja Even a , Xuguang Chi b , Heidi Bauer e , Hans Puxbaum e , Jean-Philippe Putaud f , Janja Tursic g , Axel Berner f a Energy Research Centre of the Netherlands (ECN), P.O. Box 1, Bdg 004, Westduinweg 3, 1755 ZG, Petten, The Netherlands b Ghent University (UGent), Institute for Nuclear Sciences, Gent, Belgium c Institut fuer Experimentalphysik, University of Vienna (UniV), Vienna, Austria d Leibniz-Institut fuer Troposphaerenforschung e.V. (IfT), Leipzig, Germany e Institute for Chemical Technologies and Analytics, Vienna University of Technology (TUV), Vienna, Austria f Joint Research Centre (JRC), Ispra, Italy g National Institute of Chemistry (NIC), Ljubljana, Slovenia Abstract We tested the comparability of methods, in use in Europe, for measuring the concentration of aerosol-carbon. The studywasperformedintheframeworkofINTERCOMP2000,afieldcampaignorganisedinthefirsttwoweeksofApril 2000inthevicinityofthevillageofMelpitz,45kmNEofLeipzig,Germany.Samplingoftheaerosoltookplacewith19 samplers.Totalcarbon(TC)wasmeasuredwithelevenmethodsandthemeanconcentrationfoundforPM10wasclose to3 mgm À3 , of which 90% was in the PM2.5 fraction. Carbon and associated compounds constituted approximately 25% of the total aerosol mass in this fine fraction. Starting point of the evaluation of the data were the concentrations stemming from two identical PM2.5 high-volume samplers, of which the samples were analysed by four institutes. The daily values of TC were highly correlated and the (random) differences were of an absolute nature, with an overall standard deviation (SD) of 0.22 (70.12) mgm À3 . This value for the SD is only twice that in the data of the individual institutes for a similar number of samples. In the series of four PM10 filter-samplers, the highest concentration was obtained with the sampler that collected the lowest amount per unit of surface area. This difference is indicative of an artefact caused by adsorption of gaseous carbon containing compounds. Evidence for such an adsorption artefact was provided by the presence of carbon in back-up filters, in amounts up to 20% of those of front filters. Adsorption can also be (part of) the explanation for a difference of 30% observed between concentrations obtained with filters and cascade impactors as samplers, because the latter collectors do not suffer from an adsorption artefact. Samples were also analysed for elemental carbon (EC). While differences of more than a factor of three between methods were observed, the correlation of the daily EC-concentrations over the period was high, better than 0.9 (R 2 ). Two institutes analysedsamplesfromfiltersandcascadeimpactorsinthesameway.BothobservedthattheEC-valuesfromthefilters were a factor of 1.4 higher than those from the impactors. Three methods were used to determine black carbon (BC) by optical means. Differences between the methods were large, but apparently of a systematic nature, because ARTICLE IN PRESS www.elsevier.com/locate/atmosenv 1352-2310/$-see front matter r 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.atmosenv.2004.08.027 Ã Corresponding author. Tel.: +31-224-56-41-48; fax: +31-224-56-34-88 E-mail address: tenbrink@ecn.nl (H. ten Brink).