INFLUENCE OF SOME AMINO-ACIDS ON THE SPONTANEOUS PRECIPITATION OF CALCIUM-OXALATE FROM HIGH IONIC-STRENGTH SOLUTIONS

Kinetics of spontaneous batch precipitation of calcium oxalate from hi gh ionic strength (0.3 mol dm-3) solutions, at PH = 6.50+/-0.05 and 29 8 K, was followed by size distribution and thermogravimetric analysis, X-ray diffraction and optical microscopy. The effect of glutamic acid , ornithine or tryptophan on nucleation, crystal growth and aggregatio n was investigated in a wide range of concentrations, including that o f physiological significance. The investigated aminoacids affected the nucleation of the solid phase. Their influence on growth and aggregat ion of crystals depended on the type and the concentration of aminoaci d used. Results are interpreted in terms of critical time and supersat uration when crystal growth or aggregation commences, control mechanis m of crystal growth and/or aggregation and the effect of aggregation o n the rate of crystal growth.