The nitroso-R salt method for the determination of cobalt in ores

Abstract

The colorimetric nitroso-R salt method for the determination of cobalt has been critically examined. A procedure developed permits cobalt to be rapidly and accurately determined in ores, without recourse to chemical separations. The use of the differential technique of colour measurement permits up to 3 per cent. of cobalt to be determined directly in a 0.2-g sample. Higher percentages of cobalt are determined by taking a suitable aliquot of the dissolved sample. Iron in large amounts causes slightly high results and, when the iron content of the ore is known or suspected to be above 30 per cent., a smaller sample weight should be used. No other knowledge of the ore composition is necessary, as other elements do not interfere.

Light Absorption Spectrometry

“…Median molar absorptivity values obtained for a solution containing 0.0400 gram of potassium chromate per liter of 0.0 5 7 potassium hydroxide solution were 3790 at 273 µ and 4820 at 373 µ, in good agreement with previous literature values. Bi Pyrocatecholsulfonaphthalein (518) lead Thiourea Ores Nitroso-R salt (195) Nitroso-R salt (492) In discussing fluorescence effects in spectrophotometry, it has been pointed out that the amount of stray light reaching the photocell should increase as the distance between the photocell and solution increases and that nonconformity of the Beer-Bouguer law at high absorbance values for some organic compounds is not instrumental in nature (63).…”