Is supersaturation relative to Ca oxalate, for example, defined relative to the saturation value in pure water at a given T and pH, or relative to empirically measured or calculated saturations in actual urine with its host of Ca binding ligands?
I understand that all urine is supersaturated with respect to Ca oxalate, so that you can expect oxalate crystals to form over time. The question is where the saturation concentrations of dissolved Ca and oxalate in urine are assumed to be the same as those of pure water at the same T and pH?