AUTOMATED AND COMPUTER-CONTROLLED METHOD FOR THE MEASUREMENT OF THE CRYSTALLIZATION OF CALCIUM-OXALATE MONOHYDRATE IN URINE

Monitoring of crystallization of calcium salts with ion-selective elec trodes has turned out to be a very sensitive method. The difficulties of handling these electrodes in native whole urine and other biologica l fluids have been eliminated by new calcium analyzers, which clean an d calibrate the electrodes after each measurement. To study crystalliz ation kinetics, repeated calcium ion measurements have to be performed at regular intervals. For this purpose we have developed a special sa mpler and software. The sampler brings a thermostat-controlled crystal lization chamber to the analyzer at preselected intervals. The compute r directs and coordinates the sampler and the analyzer, stores the rec eived results and prints out growth curves. Furthermore it calculates the half-time (h) and the maximum decrease of ionic calcium at infinit e incubation time (Delta Ca-infinity(2+)). Both values are shown to ch aracterize the growth of calcium oxalate monohydrate in urine. Results are obtained within 40 min.