Potentials of Infrared Spectroscopy and X-Ray Structural Analysis in Assessing Mineral Composition of Urinary Concrements

Abstract

This paper presents the results of the combined use of infrared spectroscopy and X-ray structural analysis in assessing the mineral composition of urinary concrement obtained during extracorporeal shock wave lithotripsy in 34 patients with urolithiasis. Registration of infrared spectra was carried out by an IKS-29 (LOMO) infrared spectrophotometer in the spectral range 4000 - 400 cm-1. X-ray structural analysis was carried out by X-ray diffraction using an X-ray diffractometer DRON-4-07. The mineral composition of 22 (64,70%) urinary stone samples according to infrared spectroscopy data, fully corresponded to the data of X-ray structural analysis. Vevellite, hydroxylapatite and uric acid were identified in most stones. In 4 (11,76%) cases, this method did not allow us to identify the phosphate component in the composition of the concrements accurately. Among the mineral components, which had the same characteristics in the infrared spectrum and corresponded to calcium phosphate, during the X-ray structural analysis, hydroxyapatite was identified in 3 (8,82%) cases, and struvite in 1 (2,94%) sample. 8 (23,52%) samples of urinary concrements had an amorphous-crystalline structure, which in the infrared spectrum was characterized by absorption bands corresponding to vevellite. When X-ray diffraction analysis of these samples was carried out, undifferentiated areas in the form of a halo were determined on the diffractogram that pointed out the presence of an amorphous phase. The data obtained demonstrate the potential of using infrared spectroscopy as the first choice method in assessing the mineral composition of urinary stones. X-ray structural analysis can be recommended as a clarifying technique in order to identify the phosphate component of stones of a crystal structure, as well as in the case of detecting rare, atypical minerals.