Flame-photometric determination of sodium and potassium in manganese ores
Two procedures are described; in one, the sample is dissolved in hydrochloric acid, interfering elements are precipitated with 8-hydroxyquinoline in ammoniacal solution, and the precipitate then extracted into chloroform. Sodium and potassium are determined in the aqueous phase by means of a filter flame photometer.
The second procedure is more suitable for routine use and involves the dissolution of the sample in hydrochloric acid, followed by the addition of sulphuric acid and aluminium nitrate to suppress interferences, and the direct evaluation of the sodium and potassium contents of the solution by means of either a prism or a filter flame photometer. Comparative results obtained by this alternative procedure on instruments of these two types are given.