TURBIDIMETRIE STUDY OF CALCIUM-OXALATE CR YSTALLIZATION

The crystallization process of calcium oxalates in synthetic urine at 37-degrees-C is followed by turbidimetry. As the solution adsorbance i s very sensitive to the number of particles in suspension, it is possi ble to distinguish nucleation and growth from agglomeration. In the fo rmer case, the slopes of the turbidimetric curves are positive whereas in the latter case, they are negative. Poisoning the solutions by som e active additives induces changes of the slopes so that it becomes po ssible to know whether the additive is a promotor or an inhibitor of n ucleation, growth or agglomeration. As an example, the model is tested for checking the influence of human urine on the crystallization proc ess. it is shown that urine fractions of non stone-formers inhibit agg lomeration when they contain macromolecules of high molecular weight ( > 30.000 Da).