Determination of Total Mercury using Thermal Decomposition with Atomic Fluorescence Detection

摘要

An improved apparatus based on thermal decomposition of the sample for the direct determination of mercury was constructed. The device consists of a quartz tube packed with a proprietary catalyst, coupled with gold preconcentration and an atomic fluorescence spectrophotometer (AFS) detector. Samples are weighed and inserted or injected into the system without pretreatment. The mercury vapors generated during thermal decomposition are catalytically reduced and passed to a gold-coated amalgamation cartridge. The mercury is released when the cartridge is subsequently heated and is detected by AFS. A valve system allows switching between combustion gas (air) and the pure argon carrier required for the atomic fluorescence detector. The performance of the system was tested using a wide range of samples: soil, sediment, coal, coal fly ash, petroleum coke, peat moss, seaweed, fish muscle, milk, blood, urine, gasoline, crude oils, and sulfur. Recoveries of mercury in the test samples were found to be 95 percent to 110 percent of the certified values. The device has a high daily throughput and requires minimal maintenance. It does not require liquid scrubbers or buffer solutions.