Abstract
Reference filters with uniformly deposited particles consisting of known masses of elemental carbon (EC) and organic carbon (OC) were prepared by a spray-drying method and an isokinetic sampling system. The submicrometer carbon particles were produced by nebulizing a carbon black hydrosol and/or a solution of potassium hydrogen phthalate (KHP). Reference filters were analyzed using representative thermal optical analysis methods (TOA) as IMPROVE and NIOSH 5040 methods, and the measured concentrations of TC, EC, and OC were compared with those measured by the gravimetric analysis. As a result, the method reported by the authors (Aerosol Sci. Technol., 41, 284 (2007)) is a simple technique for preparing the reference EC/OC filters in which EC, OC, and mixed EC-OC particles of a controlled size, mass, and chemical composition are deposited uniformly. These reference filters are invaluable in evaluating TOA methods of EC/OC measurement.
