New Approach for the Determination of Fluorine in Glass

Nijhuma Kayal and Nahar Singh

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Fluorine, Glass, Decomposition, Lanthanum chloride.


The properties of glass critically depend on glass composition. Apart from silica, calcium and aluminium; fluorine is also an essential constituent of the glass, since it enhances several properties of glass. In view of the increasing use of fluorine in glasses, it is necessary to have a rapid, accurate and cost effective method for the determination of fluorine in glass. Keeping the above facts a simple and rapid method has been developed for the quantitative estimation of fluorine in glass materials. The method proposed is based on extraction of fluorine from the glass sample by decomposing the glass sample with fusion mixture of sodium carbonate and zinc oxide. The fluorine is extracted with distilled water and is determined by using lanthanum chloride as titrant. The accuracy of the method has been established by analyzing five replicates of Standard Reference Material of NBS 91 and four different glass samples. The standard deviation has been calculated by analyzing five replicates of each glass sample and reference material by the method proposed. The method proposed is reproducible and the standard deviation in the determination of five replicates is found to <1.3%.