SOME FACTORS CAUSING VARIABILITY IN HIGH VOLUME SAMPLING OF AIR.

As with most systems involving calibration, sampling, manipulation and chemical analysis, high volume sampling of airborne particulate matter is subject to many sources of variability and error. The paper discusses the extent of possible variation in the analytical results if X-ray Fluoroescence Analysis of certain metals is performed directly on the filter rather than by Atomic Absorption Spectroscopy on the acid extract of a strip of the filter. The distribution of various constituents of the particulate matter across the filter and the possibility of exhaust air from the sampler being reentrained are also examined. The limited amount of study undertaken indicates that copper contamination of the sample is occurring. The most likely source is the commutator of the brush type motor used in the sampler.