CHLORIDE ANALYSIS OF SINGLE AEROSOL-PARTICLES

A selective and quantitative method fbr the determination of water-sol uble chloride in single aerosols has been developed for the mu m and s ub-mu m range. The method, a so-called spot test, is based on the chem ical reaction between chloride and silver nitrate. The chloride-contai ning particles are collected on a glass slide which is coated with sil ver nitrate dispersed in a gelatin film. In a closed thermostatic cham ber the soluble chloride salts dissolve at a relative humidity of 100 % and react with silver nitrate. The inslouble reaction product AgCl e xhibits characteristic precipitation rings around the particles which can be observed by light or scanning electron microscopy. A correlatio n between the chloride mass of a single particle and its corresponding reaction ring, the so-called halo, has been established. (C) 1998 Els evier Science Ltd. All rights reserved.