Determination of Arsenic and Mercury in Iron Ores by Water-bath Digestion-Hydride Generation-Atomic Fluorescence Spectrometry with a Sequential Injection System

A convenient method was established to determine arsenic and mercury contents in iron ores. The iron ores were dissolved in HNO₃-HCl solution by water-bath digestion at low temperature, and the determinations of arsenic and mercury contents were performed by hydride generation-atomic fluorescence spectrometry with a sequential injection system. The choice of digestion reagents is discussed in this paper. Some important interference factors were studied to obtain the optimum measurement conditions, e.g the concentration of KBH₄ solution, the flow rate of carrier gas, the flow rate of coolant gas, acid and acid-base proportion. The linear range was from 0 to 100 g/L for arsenic, and from 0 to 10 g/L for mercury. The detection limit of arsenic and mercury is 0.06 g/L and 0.05 g/L respectively. The method has been applied to determine arsenic and mercury contents in iron ores. Arsenic content is shown to have a RSD less than 3.56% and recovery of 90.0%-110.0%, and mercury content is shown to have a RSD less than 2.87% and recovery of 90.0%-105.5%. The results of actual samples with this method were in good agreement with those obtained by the airproof-microwave digestion method.