Titrimetric determination of silver,chloride and bromide in glasses

Titrimetric methods are described for the determination of total silver, free silver or free halide (Cl, Br and I), and bromide (or iodide) in glasses. Total silver is titrated potentiometrically with standard bromide solution after hydrofluoric—sulfuric acid sample decomposition followed by sodium hydrogensulfate fusion for volatilizing hydrogen halide. Free silver is determined similarly on a separate sample without the fusion step. For glasses containing excess of halide, free halide is titrated potentiometrically with standard silver(I) solution after dissolution of the sample in ice-cold hydrofluoric—nitric acid. Total bromide (or iodide) is determined by iodometric titration after oxidation to bromate (or iodate) with hypochlorite solution. The methods have been applied to a wide range of complex glass compositions and results are compared with values obtained by controlled-potential coulometry and x-ray fluorescence analysis.