Assessment and maintenance of the quality of urolith analyses in a comparison of methods. 4th International Ring Test to check quality.

For five test samples of the fourth International Ring Test to check the quality of methods for urinary calculus analysis, 45 findings obtained by 10 different methods were sent from 16 countries. The mean deviation of 0.11 molecular parts per component for all five samples is considerably low. The average standard SQ for all participants is 2.44. It falls off from X-ray diffraction via IR down to other quantitative methods. Advantages and disadvantages of X-ray diffraction and IR-spectroscopic analyses are discussed. Analysis of urinary calculi according to centralized, methodically uniform standards offers advantages in analytical quality.