A rapid and accurate method with high reproducibility for the turbidimetric determination of caesium in contaminated sodium fire residue, with use of an ultraviolet-visible spectrophotometer, has been developed. In this method, sodium tetraphenylborate was used as an analytical reagent to produce stable turbidity arising from the formation of caesium tetraphenylborate, which has very low solubility. In order to standardise the test conditions, various parameters affecting the analytical scheme were investigated.
Sahoo, P., Parida, F. C., Sivasubramanian, K., & Rao, S. R. M. (1990). Turbidimetric determination of caesium in contaminated sodium fire residue. The Analyst, 115(8), 1129-1132. https://doi.org/10.1039/AN9901501129