Reference number
ISO 1620:1976
ISO 1620:1976
© ISO 2024
International Standard
ISO 1620:1976
Cryolite, natural and artificial — Determination of silica content — Reduced molybdosilicate spectrophotometric method
Edition 1
1976-09
1976-09
ISO 1620:1976
6217
Published
(Edition 1, 1976)
This publication was last reviewed and confirmed in 2022.
Therefore this version remains current.
Abstract
Specifies methods of test for natural and synthetic materials having a molar ratio sodium fluoride/aluminium trifluoride between 3 and 1,7 approximately. The method is applicable to products the phosphorus pentoxide content of which does not exceed 0,02 % (m/m). The procedure consists in alkaline fusion of a test portion by means of a mixture of sodium carbonate and boric acid. Dissolution of the fused mass in excess nitric acid so that the pH value is between 0,7 and 0,9. Formation of the (Yellow) oxidized molybdosilicate under clearly defined conditions of acidity, temperature, time and concentration of reagents. Selective reduction in the presence of tartaric acid and measurement at a wvelength of about 815 nm.
General information
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Status: PublishedPublication date: 1976-09Stage: International Standard confirmed [90.93]
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Edition: 1Number of pages: 5
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Technical Committee :ISO/TC 226ICS :71.060.50
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