US EPA

157125 

Journal Article 

Summary of organic and elemental carbon/black carbon analysis methods and intercomparisons 

Watson, JG; Chow, JC; Chen, LWA 

2005 

Yes 

Aerosol and Air Quality Research
ISSN: 1680-8584
EISSN: 2071-1409 

5 

1 

69–102 

English 

Many different thermal, optical, and thermal/optical carbon analysis methods for organic carbon (OC), elemental carbon (EC) or black carbon (BC) have been applied throughout the world to evaluate visibility and the Earth's radiation balance. Dozens of intermethod and inter laboratory comparison studies have been conducted. Several of these studies are catalogued and summarized here. BC or EC concentrations are found to differ by up to a factor of 7 among different methods; factor of 2 differences are common. Differences between methods are not consistent among comparison studies, with some methods showing higher BC for one set of samples and lower BC for other sets relative to a common benchmark. The absorption efficiency relating light absorption (b sub(abs)) to EC that is derived from collocated optical and chemical measurements can vary by a factor of 10, depending on the collocated b sub(abs) and EC measurement methods. Future intermethod and interlaboratory comparisons must include components that seek to understand the causes of these differences.