Positive artifact in the measurement of particulate carbonaceous substances using an ambient carbon particulate monitor

An ambient carbon particulate monitor (ACPM), which is a commercially available instrument for automatic continuous measurement of particulate carbon, has been used in the recent studies. In order to investigate the amount of the positive artifact in the measurement of particulate carbonaceous substances by the ACPM, field duplicate experiments using two ACPMs and a parallel plate organic denuder were conducted in urban and rural atmosphere. The ACPM measurements without the denuder are at risk of overestimating the results for organic carbon (OC) and total carbon in aerosols because of the positive artifact derived from organic vapors in the sample air stream. On the other hand, the measurement of OC evolved at higher temperatures (250–340°C) and elemental carbon in aerosols are not significantly affected by the positive artifact. The ACPM measurements with the denuder give the lower-limit concentrations of particulate carbonaceous substances.