Air quality monitoring: total gaseous mercury

Ambient air is introduced through a filtered inlet via a heated sample line to a Tekran Model 2537A\B mercury vapour analyzer. The concentration of gaseous mercury is determined using cold vapour atomic fluorescence spectroscopy. Five minute integrated concentrations at the ng/m³ level are averaged and reported as hourly concentrations. The Tekran Model 2537A\B is equipped with dual gold cartridges (arranged in parallel) to allow continuous sampling of the inlet stream by alternating sampling and analysis steps on each cartridge. While one cartridge is adsorbing mercury during a sampling period, the other cartridge is desorbed and analysed. An internal (Hg vapour) permeation source is used in conjunction with a zero air generator to automatically calibrate the analyser once every 25 hours.