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Updated: Jun 28, 2026

Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area
Published on: February 19, 2018
Photometric determination of niobium with azo-dyestuffs
1V. I. Vemadsky Institute of Geochemistry and Analytical Chemistry U.S.S.R. Academy of Sciences, Moscow V-334, U.S.S.R.
Abstract:
The azo-dyestuffs, which contain the analytically functional O,O'-dioxyazo group and are widely employed as photometric reagents for niobium, are reviewed. Two new groups of reagents are described : mono-azo-dyestuns based on R-salt and 2,7-bisazo dyestuffs based on chromotropic acid. The reaction with niobium is sensitive (epsilon = 20,000 to 40,000), selective and takes place in strongly acidic solution (0.5-6M hydrochloric or nitric acid). It is possible to extract with butanol the diphenylguanidine salt of the corresponding niobium complex and to measure the absorbance of the extract.
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