ISO 5935:1984

Crude sodium borates for industrial use — Determination of total and alkali-soluble silica contents — Molybdosilicate spectrometric method

Specifies a method using test solutions to be prepared by fusion of a test portion with sodium carbonate for the determination of the total silica content, and by dissolution of the alkalisoluble part of a test portion in sodium hydroxide solution for the determination of the alkali-soluble silica content. This results in the formation of molybdosilicate, followed by spectrometric measurement at a wavelength of about 400 nm. Applies to products having total silica contents in the range 0,4 to 4,0 % (m/m) and alkali-soluble silica contents in the range 0,01 to 0,05 % (m/m).