A fast and accurate microwave-assisted digestion method for arsenic determination in complex mining residues by flame atomic absorption spectrometry

摘要

A fast and accurate microwave-assisted digestion method for arsenic determination by flame atomic absorption spectrometry (FAAS) in typical, complex residues from gold mining is presented. Three digestion methods were evaluated: an open vessel digestion using a mixture of HG:HNO_3:HF acids (Method A) and two microwave digestion methods using a mixture of HCl:H_2O_2:HNO_3 in high (Method B) and medium-pressure (Method C) vessels. The matrix effect was also investigated. Arsenic concentration from external and standard addition calibration curves (at a 95% confidence level) were statistically equal (p-value = 0.122) using microwave digestion in high-pressure vessel. The results from the open vessel digestion were statistically different (p-value = 0.007) whereas in the microwave digestion in medium-pressure vessel (Method C) the dissolution of the samples was incomplete.