微波消解-氢化物发生原子荧光光谱法和质谱法测定高有机质无烟煤中汞砷的可行性研究

Feasibility Study on Content Determination of Mercury and Arsenic in High Organic Anthracite by Microwave Digestion-Hydride Generation-Atomic Fluorescence Spectrometry and Mass Spectrometry

微波消解技术适用于处理大部分煤炭样品,但对于高有机质含量的无烟煤样品,因其煤化程度高,含有多种复杂的高分子有机化合物,应用现有的消解技术不能将其完全消解。本文对微波消解的实验条件包括消解试剂、消解温度及消解时间进行优化,确定了适合处理高有机质无烟煤的消解体系,评价了采用HG-AFS和ICP-MS测定其中总汞和总砷含量的可行性。结果表明,以硝酸-硫酸-氢氟酸（6∶4∶0.5）作为微波消解试剂,消解温度达205℃,保持30 min可将高有机质含量的无烟煤彻底分解,其中硫酸对无烟煤的消解起到了关键作用;ICP-MS与HG-AFS对汞的检测结果一致,回收率都达到98%以上,但由于砷的化学形态复杂,有机态砷不能全部转化无机态砷使得HG-AFS对砷的检测结果偏低。因此,对于有机质含量特别高（81%-90%）的煤炭样品,微波消解可将其彻底转化为溶液,用ICP-MS可以准确定量其中的汞和砷,而HG-AFS不能作为检测砷的有效手段。

The microwave digestion method can be used for most coal samples, but not for those with ultra-high organic matter because they contain multiple complex high molecular organisms due to the high coalification degree and cannot be digested by digestion techniques currently available. In this paper, the conditions for microwave digestion including digestion reagents, temperature and time were investigated. The digestion system suitable for anthracite with high organic content was investigated and the feasibility on determination of total Hg and As by Hydride Generation - Atomic Fluorescence Spectrometry （ HG-AFS ） and Inductively Coupled Plasma-Mass Spectrometry （ICP-MS） was investigated. Results show that using nitric acid-sulfuric acid-hydrofluoric acid （6：4 ：0.5） as the digestion reagent and the digestion temperature of 205℃ for 30 minutes, the anthracite with high organic content can be completely digested due to the key role of sulfuric acid. The detection results of mercury by HG-AFS and ICP-MS were consistent, both recoveries of which reach more than 98%. The result of arsenic by HG-AFS was significantly lower due to incomplete transformation of organic As to inorganic As. Therefore, anthracite with high organic content （81% - 90 % ） can be completely digested to solution by microwave technique, and Hg and As can be determined by ICP-MS. HG-AFS is not an efficient method to analyze mercury.