The quality of analytical results obtained for polycyclic aromatic hydrocarbons (PAHs), monitored at three sites of the Dutch National Precipitation Chemistry Network (LMR) was evaluated. Also, the possibility of applying a single sampling method for analysis of both PAHs as well as a selected group of pesticides, in the LMR, was investigated. The influence of several parameters was investigated using an experimental design. The measurements were organized as a conversation experiment. At regular time intervals samples form the conservation bottles were analysed both on the amount PAHs and the amount of the selected pesticides. The statistical evaluation of the measurement results yields some conclusions with respect to the influence of the selected parameters on the measurement results. Using the present sampling technique the addition of coppersulfate appears to have a negative influence on the stability of cyanazine, one of the nitrogen containing pesticides, and a positive effect on the stability of the chlorophenoxycarboxylic acids. Other parameters which had systematic effects on the results were the fact whether open or closed container bottles were used and the type of rain gauge. An indication of the quality of the measurement results is given although the influence of the matrix and of ambient conditions, like the temperature, is not yet studied sufficiently.<br>