Precipitation of Pyrophosphate and Triphosphate with Tris(ethylenediamine)cobalt(III) Chloride and Hexamminecobalt(III) Chloride

Examination of Oxyacids of Phosphorus by Electrochromatography

“…Many chemical procedures that have been devised for the detection (7,11,28, 43, 69), estimation (8,9), and separation (27,35,88,46) of the phosphorus oxyacids, including colorimetry (20,84,37), titrimetry (2,22,44,68), and precipitation (35, 4^~44, 66), are not widely applicable to complex mixtures, particularly to those containing interfering substances. Differential migration methods such as paper chromatography have served for the examination of various oxyacids (1, 18, 31), some condensed acids (10, 15-17, 29, 59, 67), and certain phosphate esters (28), especially when supplemented by sensitive colorimetric methods for the detection of the separated substances (84).…”

Determination of Triphosphate in Commercial Triphosphate and Detergents Built with Triphosphate

“…Control of pH. Previous workers (8) have shown that the precipitation of triphosphate with tris(ethylenediamine) cobalt-(III) ion is nearly quantitative between pH 3 and pH 4, and that the completeness of precipitation falls rapidly outside this range. A sodium acetate-acetic acid buffer (4) giving a pH of 3.6 was used to ensure maximum completeness of precipitation.…”

Precipitation of Zinc Phosphates from Solutions of Sodium Ortho-, Pyro-, and Triphosphate

“…Several published methods for the determination of triphosphate and pyrophosphate involve the use of zinc ions for the precipitation of one or both of these phosphates (3, 4, 6, 7, 16,19,26,27,31). In some of the supporting experiments on which the methods are based, and in the studies of condensed phosphate precipitations by other metal ions such as manganese(II) (17), and tris(ethylenediamine) cobalt(III) (21), there is evidence that pyrophosphate and triphosphate are harder to separate from each other than orthophosphate or trimetaphosphate. Recent work (21), as well as the present study, indicates that pyrophosphate and triphosphate usually coprecipitate.…”