U.S. Army Engineer Research and Development Center, Environmental Laboratory, 3909 Halls Ferry Rd., Vicksburg, MS 39180, United States.
Talanta. 2010 Jan 15;80(3):1257-63. doi: 10.1016/j.talanta.2009.09.017.
Interest in tungsten occurrence and geochemistry is increasing due to increased use of tungsten compounds and its unknown biochemical effects. Tungsten has a complex geochemistry, existing in most environmental matrices as the soluble and mobile tungstate anion, as well as poly- and heteropolytungstates. Because the geochemistry of tungsten is substantially different than most trace metals, including the formation of insoluble species under acidic conditions, it is not extracted from soil matrices using standard acid digestion procedures. Therefore, the current work describes a modification to a commonly used acid digestion procedure to facilitate quantification of tungsten in soil matrices. Traditional soil digestion procedures, using nitric and hydrochloric acids with hydrogen peroxide yield <1 up to 50% recovery on soil matrix spike samples, whereas the modified method reported here, which includes the addition of phosphoric acid, yields spike recoveries in the 76-98% range. Comparison of the standard and modified digestion procedures on National Institute of Standards and Technology Standard Reference Materials yielded significantly improved tungsten recoveries for the phosphoric acid modified method. The modified method also produces comparable results for other acid extractable metals as the standard methods, and therefore can be used simultaneously for tungsten and other metals of interest.
由于钨化合物的使用增加及其未知的生化效应，人们对钨的存在和地球化学的兴趣日益增加。钨具有复杂的地球化学性质，它以可溶性和移动性的钨酸盐阴离子以及多钨酸盐和杂多钨酸盐的形式存在于大多数环境基质中。由于钨的地球化学性质与大多数痕量金属有很大的不同，包括在酸性条件下形成不溶性物质，因此不能使用标准的酸消解程序从土壤基质中提取。因此，目前的工作描述了对常用酸消解程序的修改，以促进土壤基质中钨的定量。传统的土壤消解程序，使用硝酸和盐酸与过氧化氢，对土壤基质加标样品的回收率<1 到 50%，而这里报告的改进方法，其中包括添加磷酸，回收率在 76-98%的范围内。国家标准与技术研究院标准参考物质的标准和改进消解程序的比较表明，磷酸改进方法的钨回收率显著提高。改进的方法还可产生与标准方法相当的其他可酸提取金属的结果，因此可同时用于钨和其他感兴趣的金属。
