Calcium oxalate crystallization in synthetic urinary medium: The impact of a more complex solution medium, organic molecules and zinc ions

Abstract

In this manuscript the impact of three organic molecules (in the presence and absence of zinc ions) in a more realistic solution medium is presented. The impact of the synthetic urinary medium on the morphology of the calcium oxalate monohydrate formed is similar to that seen in the presence of citric acid, the dominant component. The particles formed are relatively flat, rounded particles. In the presence of zinc ions, the particles are little changed with the main change being more rounded particles. The presence of the different organic acids show different impacts for different organics. Ethylenediamintetraacetic acid complexes calcium ions and lowers the supersaturation as a chelator would be expected to. It also impacts the growing crystal changing the morphology. In the case of tartaric acid, adsorption onto critical nuclei and/or growth features leads to incorporation. Finally, the most complex impact was found for maleic acid. Maleic acid interacts with citric acid, inhibiting the citric acid effect. This can be seen in the morphology of particles being similar to those in pure water. The presence of zinc ions generally led to zeta potential values that were closer to zero and therefore would increase the propensity for these particles to coagulate.