Emission spectrographic determination of mercury in the atmosphere

A method was described for the emission spectrographic determination of mercury in the atmosphere. No previous report could be found in regard to chemical forms of mercury in the atmosphere. So in order to collect all forms of mercury in the atmosphere, an activated carbon filter (Whatman ACG/B) was examined. The filter contains activated carbon, finely divided and evenly distributed throughout a celluloseglass fiber mat. Therefore, it was considered that mercury vapor was taken up by the activated carbon and that particles bearing mercury were collected on the filter mat. The filter had a filtration efficiency of 99.95% for the particles whose mean size was 0.6 μm in diameter. However, the filter was inefficient sorbent for mercury vapor. So in order to increase its sorbent efficiency for mercury vapor, the filter was impregnated with iodine. The filter was immersed in 20 ml of 0.02 N iodine solution for 10 minutes and dried in a silica gel desiccator for 1024 hours. Addition of iodine to the filter greatly increased its sorbent efficiency for mercury vapor and the iodine-impregnated activated carbon filter adsorbed mercury vapor with an efficiency of 100% at a face velocity of 36 cm/sec. Therefore, mercury compounds in the atmosphere were collected by drawing air through the iodine-impreg-nated activated carbon filter 48 mm in diameter at a flow rate of 30 l/min for 57 days. A high-purity graphite electrode, 6.2 mm in diameter with a cup 12.7 mm in depth and 4.8 mm in diameter was immersed in a carbon tetrachloride solution of 5% paraffin for a few minutes and dried at 80°C. Sample disks, prepared by cutting in 4 mm in diameter from the sample filter were packed in the crater of the electrode. The total charge in the electrode is usually 12 disks. A 200 μl aliquot of internal standard solution containing 100 μg/ml of arsenic was added dropwise. The arsenic was chosen for an internal standard element on the basis of investigating the vaporization patterns of mercury and arsenic obtained by the moving plate method. The electrode was dried in a silica gel desiccator for 1024 hours to remove the water dropped because more than 20 μl of water in the electrode appeared to decrease spectral line intensity. A boiler cap 6.2 mm in inner diameter with an orifice machined in 2.4 mm in diameter was put on the electrode. The boiler cap with an orifice diameter of 1 mm was commercially available. However, the boiler cap 2.4 mm in orifice diameter was selected from the