Antimonyl sulfate

Yoshimura et al. [193] carried out microdeterminations of phosphate by gel-phase colorimetry with molybdenum blue. In this method phosphate reacted with molybdate in acidic conditions to produce 12-phosphomolybdate. The blue species of phosphomolybdate were reduced by ascorbic acid in the presence of antimonyl ions and adsorbed on to Sephadex G-25 gel beads. Attenuation at 836 and 416 nm (adsorption maximum and minimum wavelengths) was measured, and the difference was used to determine trace levels of phosphate. The effect of nitrate, sulfate, silicic acid, arsenate, aluminium, titanium, iron, manganese, copper, and humic acid on the determination were examined. 

This ammonium phosphomolybdate complex is yellow, but if mildly reduced by ascorbic acid in the presence of potassium antimonyl tartrate a solution of stable bluish-purple color ( molybdenum blue ) develops after about ten minutes, which has its strongest absorption at 882 pm (Fig. 4.6). Other mild reducing agents have also been used, including tin(II) chloride, or hydrazine sulfate, which give maximum absorbances at slightly different wavelengths. The intensity of the color which develops is linearly proportional to the... 

Electrolytes which do not afford ionic complexes with common hexitols and reducing sugars are aqueous solutions of lead acetate, copper sulfate, zinc sulfate, ferrous ammonium sulfate, calcium chloride, potassium dichromate, ferric chloride (pH 3), aluminum sulfate, magnesium sulfate, sodium sulfate, potassium antimonyl tartrate, sodium arsenate or arsenic acid, sodium phosphate, and hydrochloric acid. It is not certain whether sodium aluminate (in 0.1 N sodium hydroxide) affords ionic complexes with carbohydrates, as aqueous alkali, alone, permits their migration during electrophoresis. 

Antimony in can be directly titrated with ceric sulfate with ferroin as the indicator. The reaction must be achieved at 50°C. The solution in the titration vessel must be sufficiently acidic to prevent the hydrolysis of the antimonyl cation SbO+ existing in these conditions. The oxidization reaction is... 

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