A rapid and simple spectrophotometric method for determining boron in glasses is devised.
A 0.100 g sample is decomposed with acid mixture of H
2SO
4, HF and H
2O
2 in a teflon beaker by heating on a water bath for 20 min. The solution is diluted to 20 m
l when the content of boron is expected to be less than 10
-3%, and to 200 m
l when the content is 10
-210
-3%. To 20 m
l of the sample solution in a polyethylene separatory funnel, Methylene Blue solution and dichloroethane are added and the mixture is shaken. After washing the organic phase with silver sulfate solution, its absorbance is measured at 660 nm. When the content of boron is a few %, a 0.010 g sample is taken and decomposed. After diluting the solution suitably, H
2SO
4 and HF are added anew to 10 m
l of the sample solution, and its solution is diluted to 20 m
l with water. Then, the determination can be carried out in the same way.
Various substances usually present in glasses do not interfere with the determination of boron. It was possible to determine 2 × 10
-5a few % of boron in glasses.
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