ISO 7990:1985 Preview
Manganese ores and concentrates -- Determination of total iron content -- Titrimetric method after reduction and sulfosalicylic acid spectrophotometric method
Method A is applicable to products having a total iron content from 1 to 25 % (m/m), and method B is applicable to products having a total iron content from 0.2 to 2 % (m/m). ISO 7990 should be read in conjunction with ISO 4297. Specifies principle, reactions (method A only), reagents, apparatus, sampling and samples, procedure and expression of results.