The Influence of Polyphosphate Ions on the Precipitation of Calcium Oxalate

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Abstract
The growth of calcium oxalate monohydrate (COM) crystals in stirred suspensions were studied by following the changes in ionic conductivity of supersaturated phosphate ion, crystallization proceeded by an initial rapid step followed by a markedly reduced growth rate as compared with that in pure supernatant solution. The initial surge was reduced as the polyphosphate concentration reached 1.6 .times. 10-6 M, which can be interpreted as evidence of either surface nucleation or the the incomplete adsorption of inhibitor at the active growth sites. In spontaneous precipitation experiments made in the presence of polyphosphate ions, the formation of calcium oxalate dihydrate and trihydrate is favored together with appreciable coprecipitation of additive ions. [This served as a model for the study of human renal baculi.].