The composition of the system used is essentially as described by Robertson et al. (6), where the growth of calcium
oxalate crystals was monitored in 50 mL of a metastable solution consisting of, per liter, 1 mmol of calcium chloride, 0.2
mmol of sodium oxalate, and 10 mmol of sodium cacodylate
buffer adjusted to pH 6.0. A constant ion strength was maintained by addition of sodium chloride to the system to give a
concentration of 0.15 mol/L. [‘4C]Oxalate was added to give
a final isotope concentration in the crystallization system of
5 uCi/L.