Positive sampling artifacts in particulate organic carbon measurements in roadside environment

Yan Cheng, Shuncheng Lee, Kin Fai Ho, Kochy Fung

Research output: Journal article publicationJournal articleAcademic researchpeer-review

7 Citations (Scopus)


The positive artifacts in particulate organic carbon measurements in a roadside environment were characterized using two filters in tandem. The experiments were performed for PM1.0, PM2.5, and PM10at 24-h interval using a URG sampler, followed by organic carbon (OC)/ elemental carbon (EC) analysis by the Interagency Monitoring of Protected Visual Environments thermal/optical reflectance carbon analysis protocol. The OC concentrations, derived from the quartz filter behind a front quartz filter, were quite similar for PM1.0, PM2.5, and PM10, ranging from 0.6 to 2.7 μg C m-3for PM1.0, from 0.7 to 2.7 μg C m-3for PM2.5, and from 1.1 to 2.7 μg C m-3for PM10. They were respectively ∼2.8%, ∼2.4%, and ∼1.6% of the particulate mass. The most abundant species on the backup quartz filters were OC2 (250°C) and OC3 (450°C), accounting for ∼80% of measured organic carbon on the backup quartz filters. It indicates the filter artifacts are mainly composed of adsorbed semi-volatile organics (below the analysis temperature of 450°C) including gaseous and particulate phase; the loading of artifacts depends on the nature of vapor and its interaction with filter substrate, rather than particle sizes. The uncorrected OC/EC ratios on the front quartz filters were ∼10% higher than the corrected OC/EC ratios by positive organic artifacts in winter, and it is ∼20% higher in summer. Another finding is that the separation distance of the front and backup filters influence the level of artifacts assessed by the backup filter. [Figure not available: see fulltext.]
Original languageEnglish
Pages (from-to)645-656
Number of pages12
JournalEnvironmental Monitoring and Assessment
Issue number1-4
Publication statusPublished - 1 Sept 2010


  • PM 1.0
  • PM 10
  • PM 2.5
  • Positive artifacts
  • Roadside

ASJC Scopus subject areas

  • Medicine(all)
  • Environmental Science(all)
  • Pollution
  • Management, Monitoring, Policy and Law


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