Solid-Phase Tungsten Speciation by Differential Digestion

In this study, a series of chemical extractions was used as a low-level, solid-phase tungsten speciation technique and correlated with XRD results. In addition to qualitative speciation, these efforts, which utilize the varying solubilities of WO(4)(-2), WO(3), and W, provide statistically representative quantitative data at environmentally relevant levels. The selective nature of the digestion procedures allowed calculation of each individual species concentration by subtracting recoveries of the composite matrices from the total tungsten determinations. The results of this method exceed the sensitivity limitations of non-destructive techniques and may provide a valuable tool in environmental forensic investigations regarding the source of tungsten contamination.