The new instrument using a TC-BC (total carbon-black carbon) method for the online measurement of carbonaceous aerosols

Abstract

We present a newly developed total carbon analyzer (TCA08) and a method for online speciation of carbonaceous aerosol with a high time resolution. The total carbon content is determined by flash heating of a sample collected on a quartz-fiber filter with a time base between 20 min and 24 h. The limit of detection is approximately 0.3 g C, which corresponds to a concentration of 0.3 gCm3 at a sample flow rate of 16.7 L min1 and a 1 h sampling time base. The concentration of particulate equivalent organic carbon (OC) is determined by subtracting black carbon concentration, concurrently measured optically by an Aethalometer, from the total carbon concentration measured by the TCA08. The combination of the TCA08 and Aethalometer (AE33) is an easy-to-deploy and low-maintenance continuous measurement technique for the high-time-resolution determination of equivalent organic and elemental carbon (EC) in different particulate matter size fractions, which avoids pyrolytic correction and the need for high-purity compressed gases. The performance of this online method relative to the standardized off-line thermo-optical OC EC method and respective instruments was evaluated during a winter field campaign at an urban background location in Ljubljana, Slovenia. The organicmatter- to-organic-carbon ratio obtained from the comparison with an aerosol chemical speciation monitor (ACSM) was OM=OC D 1:8, in the expected range.