Quality assurance and quality control for thermal/optical analysis of aerosol samples for organic and elemental carbon

• Published in: Analytical and bioanalytical chemistry Vol. 401; no. 10; pp. 3141 - 3152
• Main Authors: Chow, Judith C., Watson, John G., Robles, Jerome, Wang, Xiaoliang, Chen, L.-W. Antony, Trimble, Dana L., Kohl, Steven D., Tropp, Richard J., Fung, Kochy K.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.12.2011
• Subjects: Aerosols; Aerosols - analysis; Air Pollutants - analysis; Analytic Sample Preparation Methods - instrumentation; Analytic Sample Preparation Methods - methods; Analytic Sample Preparation Methods - standards; Analytical Chemistry; Biochemistry; Calibration; Carbon; Carbon - analysis; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Food Science; Laboratory Medicine; Monitoring/Environmental Analysis; Original Paper; Quality assurance; Quality Control; Sampling; Sound filters; Thermal/optical carbon analysis; Organic carbon; Pyrolysis; Quality assurance; Aerosol; Quality control; Elemental carbon; IMPROVE_A protocol
• ISSN: 1618-2642; 1618-2650
• DOI: 10.1007/s00216-011-5103-3

Accurate, precise, and valid organic and elemental carbon (OC and EC, respectively) measurements require more effort than the routine analysis of ambient aerosol and source samples. This paper documents the quality assurance (QA) and quality control (QC) procedures that should be implemented to ensure consistency of OC and EC measurements. Prior to field sampling, the appropriate filter substrate must be selected and tested for sampling effectiveness. Unexposed filters are pre-fired to remove contaminants and acceptance tested. After sampling, filters must be stored in the laboratory in clean, labeled containers under refrigeration (<4 °C) to minimize loss of semi-volatile OC. QA activities include participation in laboratory accreditation programs, external system audits, and interlaboratory comparisons. For thermal/optical carbon analyses, periodic QC tests include calibration of the flame ionization detector with different types of carbon standards, thermogram inspection, replicate analyses, quantification of trace oxygen concentrations (<100 ppmv) in the helium atmosphere, and calibration of the sample temperature sensor. These established QA/QC procedures are applicable to aerosol sampling and analysis for carbon and other chemical components. Figure Distributions of the 3,460 OC and EC replicate analyses of the IMPROVE filter samples collected between January 01, 2006 and December 31, 2011 using 11 DRI Model 2001 thermal/optical carbon analyzers