Loss of PM2.5 Nitrate from Filter Samples in Central California

Abstract Evaporative loss of particulate matter (with aerodynamic diameter 80% during warm months. In agreement with theory, evaporative loss from quartz-fiber filters in nitric acid denuded samplers is controlled by the ambient nitric acid-to-particulate nitrate ratio, which is determined mainly by ambient temperature. Accurate estimation of nitrate volatilization requires a detailed thermodynamic model and comprehensive chemical measurements. For the 14-month average of PM2.5 acquired on Teflon-membrane filters, measured PM2.5 mass was 8–16% lower than actual PM2.5 mass owing to nitrate volatilization. For 24-hr sa...