DETERMINATION OF TOTAL GASEOUS MERCURY IN AIR AT BACKGROUND LEVELS

A method is described for the determination of the total gaseous mercury in air at concentrations ranging from ca. 0.1 ng m-3 to 1μg m-3. The method is based on the collection of mercury species on gold-coated quartz wool followed by detection with an atomic absorption detector. The collection efficiencies for mercury, dimethylmercury, methyl-mercury(II) chloride, and mercury(II) chloride are nearly quantitative at flow rates up to 10 1 min-1 and at temperatures up to 50°C. The absolute detection limit of the method is 20 pg of mercury. Under field conditions the precision of the analytical procedure was 14.5% (n=5) for 400-l samples of air and a mercury concentration of 1.5 ng m-3. Measurements of the mercury distribution in the atmosphere show an ambient background level in clean air masses of 1.0-4.0 ng m-3. © 1979.