Determination of mercury in minerals by combustion/trap/atomic fluorescence spectrometry

Abstract

The combustion/trap technique has been improved and extensively used since its development in 1995 for the determination of mercury (Hg) in various refractory samples. The present work adapted the technique to the determination of mercury in mineral samples using tantalum boats for introducing samples into the combustion system. NIST reference standards and other certified reference materials physically and chemically similar to samples to be analyzed were used for calibration. The analytical performance of the adapted method was evaluated by analyzing certified reference mineral samples and comparing with traditional acid digestion methods. The technique was also compared statistically with different methods on analyzing mineral samples with different concentration levels. Combining with the use of sensitive atomic fluorescence spectrometry (AFS) the method detection limit was found to be around 0.1 ng g⁻¹. Recoveries of the technique were up to 20% higher than wet digestion methods for samples with Hg concentrations >10 ng g⁻¹, and up to 70% higher for samples with Hg concentrations <10 ng g⁻¹. The RSDs generated by the technique were generally around 8% (about half of RSDs by wet digestion methods). Due to its unique advantages the application of the combustion/Trap/AFS technique in material sciences is promising.