Structural and microstructural chracterization of seven human kidney stones using FTIR spectroscopy, SEM, thermal study and X-ray Rietveld analysis

Abstract

Abstract Structural and microstructural parameters of seven kidney stones (UKS1–UKS7) retrieved from patients of eastern India were investigated using FTIR spectroscopy, scanning electron microscopy, thermogravimetric analysis and X-ray powder diffractometry. Quantitative phase analysis of kidney stones was performed following the Rietveld method. Crystallite sizes and thermal stability were evaluated from the X-ray peak-broadening analysis and thermogravimetric study. Rietveld analysis of X-ray powder diffraction data indicates that kidney stones are a mixture of phases with whewellite as the major constituent in UKS1–UKS4 and UKS7, whereas the major phase in UKS5 and UKS6 is anhydrous uric acid. The crystallite size of whewellite phase in stones with more than 50 wt% of whewellite (UKS1-UKS4 and UKS7) varies from 149(5) to 182(1) nm, whereas the corresponding sizes of uric acid crystallites in stones with more than 50 wt% of uric acid (UKS5 and UKS6) are 163(2) and 190(3) nm, respectively. Thermogravimetric analysis (TG) of UKS1 reveals that whewellite is stable upto 400 K and above this temperature anhydrous calcium oxalate is formed, which tranforms into calcium carbonate at 750 K and finally to calcium oxide above 970 K. The kidney stone UKS5 with more than 90 wt% of uric acid is stable upto 708 K.