Evaluation of analytical methods to address tungsten speciation

Tungsten in solution may exist as a wide variety of species depending on concentration, pH, and aging time. Despite a substantial number of studies on this topic, the speciation of tungsten in aqueous solutions is still not completely understood. To address issues of fate, transport and potential bioavailability, it is necessary to be able to assess the speciation of tungsten in environmental systems. This study investigates the use of Laser Desorption/Ionization mass spectrometry combined with a Time-of-Flight mass analyzer (LDITOF) as well as Raman spectroscopy as potential techniques in speciation studies. Raman spectroscopy has been successful in identifying the dominant species under a narrow range of conditions. The ultimate goal is to extend the range of conditions and concentrations while also identifying subordinate species.