ASTM D6722-19,Standard Test Method for Total Mercury in Coal and Coal Combustion Residues by Direct Combustion Analysis.
ASTM D6722-19 cover procedures to determine the total mercury content in a sample of coal or coal combustion residue.
4. Summary of Test Method
4.1 Controlled heating of the analysis sample in oxygen is used to liberate mercury. The sample is heated to dryness in the instrument and then thermally and chemically decomposed.The decomposition products are carried by flowing oxygen to the catalytic section of the furnace, where oxidation is completed and halogens as well as nitrogen and sulfur oxides are trapped. The remaining decomposition products are carried to a gold amalgamator that selectively traps mercury. After the system is flushed with oxygen to remove any remaining decomposition products, the amalgamator is rapidly heated,releasing mercury vapor. Flowing oxygen carries the mercury vapor through absorbance cells positioned in the light path ofa single wavelength atomic absorption spectrophotometer.Absorbance peak height or peak area, as a function of mercury concentration is measured at 253.7 nm.
4.2 Mercury and mercury salts can be volatized at low temperatures. Precautions against inadvertent mercury losss hould be taken when using this method.
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