Discriminant analysis of urinary calculi by near-infrared reflectance spectroscopy.

Near-infrared reflectance analysis has been used to determine the qualitative and semi-quantitative composition of urinary calculi. This simple method requires calibration of the most common urinary calculi. Analysis time is short (less than 1 min) and only very small amounts of calculus in powder form (less than 100 micrograms) are required without the use of any reagent. Moreover, when compared to infrared spectroscopy, this method provides sufficient accuracy to identify mixed calculi containing two or three components, and permits semi-quantitative determinations. The speed and simplicity of this technique makes it a powerful method for the routine analysis of urinary calculi in clinical laboratories.