Determination of the Stability Constant of the Calcium Dioxalate Complex
The problem of calcium oxalate (CaOx) urinary calculi is often best understood in terms of the supersaturation of calcium oxalate in urine. Relative supersaturation can be determined by incubation of urine with solid CaOx. An alternative involves measuring various species concentrations and then calculating relative supersaturation with a computer equilibrium program. Minor discrepancies exist between these two methods at low concentrations of calcium and oxalate1. At high oxalate concentrations, however, there is a large discrepancy between the two methods: incubation yields a lower relative supersaturation. Such a difference can be accounted for, at least in part, by assuming the existence of a CaOx species not included in the current computational scheme. Studies done with divalent cations, such as magnesium, cadmium, and cobalt, have demonstrated the existence of dioxalate species at high oxalate concentrations 2. On this basis, a calcium dioxalate species, Ca(C2O4) 2 2- could be anticipated at high oxalate concentration.
KeywordsActivity Coefficient Stability Constant Calcium Oxalate Species Concentration Calcium Oxalate Monohydra
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