Accurate spectrophotometric method for the determination of silica in rocks, minerals and related materials
Two main spectrophotometric methods have been used to determine silica: those using the yellow molybdosilicic acids and those using the molybdenum blue complex. Conditions for the production of a stable molybdenum blue complex have been re-investigated. Using suitable conditions, and a modern spectrophotometer with high reproducibility, a rapid and accurate method for the determination of silica has been developed. An important feature of the procedure is the inclusion of an “activation” stage for the silicic acid before complex formation.
The method has been applied to a variety of international standards and gives accurate results with a coefficient of variation of 0.5% at the 50% silica level.