USE OF RAMAN-SPECTROSCOPY FOR THE QUANTITATIVE-ANALYSIS OF CALCIUM-OXALATE HYDRATES - APPLICATION FOR THE ANALYSIS OF URINARY STONES

The potential use of the Raman spectroscopy (RS) for the quantitative analysis of the mineral components of urinary stones consisting mainly of the mono- and dihydrate salts of calcium oxalate has been demonstr ated. The quantitative analysis was based on the construction of calib ration curves made of known mixtures of synthetically prepared pure ca lcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD), T he Raman spectra of well-mixed powdered samples of COM and COD were re corded, and the characteristic bands at 1462 and 1477 cm(-1) for COM a nd COD, respectively, were used as the basis for the quantitative anal ysis. It was found that x(M) = (I-R - 0.134)/(0.8I(R) + 1.52), where x (M) is the molar fraction of COM in the solid mixture anti I-R represe nts the intensity ratio of the Raman band at 1462 cm(-1) to that of 14 77 cm(-1). The calibration curve was used for the analysis of a typica l urinary stone surgically removed, and it was found that x(M) = 0.33. This finding was confirmed by infrared quantitative spectroscopic ana lysis. Quantitative analysis using the proposed Raman technique had a detection limit of approximately 0.6 mol % content in COM. The relativ e advantage of RS lies in its potential use as a nondestructive analyt ical technique for the mineral composition of urinary stones.