Re-usable sampling tubes for monitoring airborne mercury vapour concentrations: sample collection and analysis by cold vapour atomic-absorption spectrometry

Abstract

A re-usable sampling tube with silvered alumina as the collection medium is used to monitor concentration levels of airborne mercury vapour. The device is ideally suited for personal sampling over long or short periods and its mercury blank is negligible. Analysis is by cold vapour atomic-absorption spectrometry, using thermal desorption to release the mercury from the sampling tube for subsequent measurement, and a novel and convenient means has been devised for altering the measurement range of the analytical system. A detection limit of 3 ng, equivalent to 0.5 µg m^–3 for a 6–1 air sample, has been achieved but this could easily be improved further by making small modifications to the analytical apparatus. The sampling and analytical procedures have been validated by comparing results obtained for samples from mercury standard atmospheres and for factory samples with those obtained by established procedures.