A Comparison of Wet Digestion and Thermal Decomposition Techniques

摘要

Despite the fundamental differences between the wet digestion and the thermal decomposition approaches to mercury analysis, excellent correlation is achieved between the two techniques. Comparative results presented here showed no analytical bias and were well within confidence limits for the two techniques.rnIt is interesting to note that the thermal decomposition technique is capable of determining mercury in coal to lower concentrations than the wet digestiontechnique. In the case of coal samples, the wet digestion process results in about a 50-fold dilution of the sample while no dilution occurs with thermal decomposition. Further, with the thermal decomposition technique, all of the mercury contained in each sample is collected (i.e. preconcentrated) on the amalgam tube before analysis further helping to lower detection limits for Hg in coal.rnThe thermal decomposition technique has two additional benefits that some laboratories may appreciate. First, with thermal decomposition no concentrated mineral acids or strong redox reagents are used. Such chemicals must be handled with care by qualified personnel and with appropriate attention to safety. Second, because the aqueous digestion step is eliminated, no aqueous hazardous waste is produced. Specifically, there are no acidic wastes high in metal content (tin, manganese, sodium & potassium) requiring disposal.