Abstract
Mg2+ and Chrome Azurol S form a red to reddish purple lake in mixed solution of ammonium chloride and ammonium hydroxide. The maximum absorption of Chrome Azurol S is at 425 mμ and that of the lake is found at 580 mμ. There is practically no absorption at 580 mμ by the dye. The formation constant, log k, of the lake would be below 1, since its coloration is disturbed by tartrate ion. The separation of Mg from the bulk of the other elements in aluminum alloys is effected by a combined use of triethanolamine, sodium hydroxide and sodium cyanide after removal of silica. The determination of Mg2+ by photometric titration with EDTA at 580 mμ can be carried out by utilizing the masking action of triethanolamine and sodium cyanide.
