Design and calibration of a low volume fog sampler

J. AerosolSci., Vol. t7. No. 3, p. 547, 1986. Prinled in Great Britain,

DESIGN

AND

0021 8502/86 $3.00+0.00 Pergamon Journals Ltd

CALIBRATION OF A LOW SAMPLER*

VOLUME

FOG

D. KLOCKOW,R. NIESSNER and B. D~.UMER University of Dortmund, Department of Chemistry, P. O. Box 500 500, D-4600 Dortmund 50, F. R. G. In this work a modified low volume round jet impactor for fog droplet sampling is presented. The impactor consists of a Teflon Rinlet and a Teflon Rcup as an impaction surface, where the fog elements are collected, form bigger drops and then flow into a receiver vessel. The sampling apparatus has been designed for constant impaction conditions, a sharp cut-off characteristic and a size cut of 10/~m to differentiate between fog droplets and nonactivated aerosol particles. The apparatus has been calibrated with monodisperse D O P aerosol as a model substance for water droplets at a constant flow-rate of 1.6 m 3 h-1. The calibration resulted in an effective cut-off diameter of 10.2/lm and a sharp cut-off characteristic. To check if, during sampling, evaporation of the collected droplets or condensation of water vapour may falsify the ion concentrations, the impactor was tested with monodisperse water droplets of well defined sodium fluorescein concentration. The liquid collected in the recipient did not exhibit a statistically significant change in concentration. A short field test in a dense fog showed that in one hour it is possible to collect a volume of fog water sufficient for ion chromatographic analysis.

*The full version of this manuscript will be submitted for publication in Journal of Aerosol Science. 547