Spontaneous Precipitation of Phosphates in Artificial Urine: Effect of Magnesium, Calcium, pH and Supersaturation

Abstract

Urinary stone disease affects a significant portion of the global population, with calcium phosphate and magnesium phosphate calculi being among the most prevalent types. In this study, we have grown crystals of DCPD and MAP using supersaturated artificial urine, which was prepared by mixing two equal volumes of solutions A and B. The aim of this investigation was to contribute to the understanding of the effect of Calcium or Magnesium concentration, supersaturation and pH on the crystallization of phosphate stones in artificial urine and the characterization of the precipitated phase. The initial molar ratio of Ca/P and Mg/P solutions was varied in the range of 0.0 to 0.35, while the solution pH was maintained between 6.0 and 8.0. The analysis of the crystals that precipitated using FT‐IR spectroscopy and X‐Ray diffraction techniques revealed that DCPD was obtained at acidic pH (6.0 and 6.5). MAP was obtained at basic pH (7.5 and 8.0). A mixture of DCPD and MAP was formed at neutral pH. The calculated supersaturation values of MAP, OCP, HAP and TCP increased with increase in pH. At lower (pH=5), the order of increasing stability is OCP<HAP<TCP<MAP<DCPD. For higher (pH=10), the order of increasing stability is DCPD<MAP<TCP<OCP<HAP.