Dry deposition contributes significantly to the acidification of ecosystems. However, difficulties in measuring dry deposition of reactive gases and fine particles make routine direct monitoring impractical. An alternate approach is to use the 'concentration monitoring' method in which dry deposition is estimated from the product of measured concentration and estimated deposition velocity. A sampling system that performs over the period of 6 hours to 7 days, depending on atmospheric concentrations, has been developed. It consists of a Teflon cyclone to exclude particles larger than about 2 micrometers, selective solid adsorption media for reactive gases - some of which are sampled from a transition flow to avoid bias from particle evaporation, a particle filter, and a final gas adsorption filter to collect the remaining trace gas. Laboratory and field tests have shown that the sampler performs well for HNO3(g).