Microwave Digestion - Hydride Atomic Fluorescence Spectra Of Arsenic, Mercury And Test New Technology And Research In The Import And Export Coal Inspection Application

The development and standardization current situation of chemical vapor generation-double channel atomic fluorescence spectrometry, the necessity of inspection and supervision on arsenic and mercury in coa is analyzed and discussed in this paper. In order to improve the ability of technical support, we have proposed three methods as follows:A new method has been described for simultaneous determination of trace arsenic and mercury in coal by microwave-assisted digestion-chemical vapor generation-double channel atomic fluorescence spectrometry. Samples are dissolved by HNO3-H2O2-HF system. The conditions of atomic fluorescence spectrometry instrument parameters for the simultaneous determination of arsenic and mercury were optimized in detail. The optimized concentrations of KBH4and HNO3required for analytes generation were2.0%(m/v) and3%(v/v), respectively. Pre-reducing pentavalent arsenic to the trivalent state was easily achieved by the addition of ascorbic acid of5%(m/v) at room temperature. Studies showed that the nitrite and nitrogen oxides generated during the reaction of digesting coal samples had not any influence on the determination of Hg and the interferences on the determination of arsenic could be eliminated by heating digestion solution under100℃or adding amino sulfonic acid. The interferences caused by other coexisting ions could be basically eliminated after adding5%(m/v) thiurea solution. The proposed method has been applied to analyze the concentrations of arsenic and mercury in three certified reference materials with satisfactory results. The detection limit of arsenic and mercury is0.033μg/L and0.002μg/L respectively. Arsenic concentration is shown to have a recovery of81.5%～104.1%, and mercury concentration is shown to have a recovery of100.0%～120.0%. The proposed method is simple, fast and sensitive, and is promising for routine analysis of trace arsenic and mercury in coal.