The determination of trace amount of molybdenum in glass

The effect of diverse elements containing in soda-lime and borosilicate glass on the thiocyanate-stannous chloride method was investigated, and in the range containing ordinarily in commercial glass almost all elements except iron did not interfere the determination of molybdenum. Color development of molybdenum thiocyanate complex was enhanced by the presence of iron, but up to the presence of a certain amount of iron, the color development was saturated. So it was proved that the effect of iron was compensated by adding a certain amount of iron to both sample and standard solution. Considering the results obtained by the investigation about the effect of diverse elements and measuring conditions, the method of the determination of molybdenum in glass was decided as follows: 1 g of powdered glass sample is taken to the platinum dish and decomposed with hydrofluoric acid and perchloric acid. The residue is dissolved by hydrochloric acid and the concentration is adjusted to 1.0 N. An aliquot containing less than 80 μg molybdenum is transferred to a separatory funnel. 3.0 mg iron and 10 ml of 10 per cent potassium thiocyanate are added and mixed. After one minute, add 5 ml of 30 per cent stannous chloride and mix. After one minute, exactly 25 ml of n-butyl acetate and shake vigorously for one minute and allow the phases to separate for 30 minutes. The absorbance of the clear n-butyl acetate extract at 460 mμ in a 1 cm cell. Blank is run through the whole procedure. Standard curve is similarly established. With this method 2.5 to 200 ppm molybdenum in soda-lime and borosilicate glass is determined. At the same time the X-ray fluorescence spectrometry was investigated. There is a linear relationship between the intensity of X-ray fluorescence of MoK sub(β) and molybdenum content by chemical analysis mentioned above, and it is proved that 25 to 600 ppm of molybdenum in glass is determined by X-ray fluorescence spectrometry. (auth.)