The rapid photometric determination of cobalt in steels using Nitroso-R-Salt

✍ Scribed by Haywood, F. W. ;Wood, A. A. R.

• Publisher: Wiley (John Wiley & Sons)
• Year: 1943
• Weight: 386 KB
• Volume: 62
• Category: Article
• ISSN: 0368-4075
• DOI: 10.1002/jctb.5000620302

✦ Synopsis

The use of nitroso-R-salt ns n specific rcngcnt for tho determination of cobnlt in steels is dcscrihed. Full development of tho cdourd cobnlt complex is obtained whcn nll minernl wid iona am ncutralieed by mcane of sodium acctntc. Other interfering elcmcnts ocauning in stfels. whilo producing wmphxes with nitroso-H.salt, am completely destroytit in an CICCBI) of nitric ncid, tho d o l t complcr being unaffected. Bneed on these investigations (L nicthod Iiw h e n devised which gives speedy, nccnrate, and reproduciblc results.

In a review of the literature on reagente producing colours with cobalt ions, nitroso-R-=It (sodium 1-nitroso-2-naphthol-3 : 6diaulphonate) appcnred to be the only one likely to be specific for cobalt in steels. This reagent, which was introduced by vnn Klooster' as a qualitative test for cobalt, produccs n red colour in neutral or buffered solutions. Other metals also produce coloura nnd prccipitcrtes, but these, rith the exception of cobnlt, nre destroyed by boiling with'nitric ncid. The rengent hoe been npplied to the deterruination of small amounts of cobalt in biological mntcrinls2~ nnd Such methods involved tedious neutralisations and separntions nnd the um of a sodium ncetate buffer for diroct neutralintion wns suggested by Marston nnd Dewey,6 who originally used a phosphate-citrate butfer, and later applied by McNaught.6 The object of the piescnt paper is to correlate past work in comexioil with the colorimetric determination of cobalt, to amplify by resenrch urork and to propom a method which is speedy, accurate, niid repetitive without being critical, by the use of the Spekker Photoelectric Abaorptiometer.