title: [Study of the transformation of weddellite to whewellite in calcium oxalate stones by x-ray diffraction].
abstract: A clay film was made of the stone powder and water drops on a slide glass and dried at 100 to 110 degrees C or at room temperature in the horizontal position for 20 calcium oxalate stones which had been received between April, 1978 and August 1980. Each clay film was scanned with an X-ray diffractometer using CuK alpha radiation, stored at room temperature in a wooden sample case and analysed again by X-ray five to seven years after the first X-ray analysis. Then the recent diffractograms of 20 powder samples were compared with the previous ones regarding the peak heights at 14.2 degrees, 14.8 degrees and 25.8 degrees (2 theta), which were considered representative of weddellite, whewellite and apatite contents and designated as Iwe, Iwh and Iap, respectively. Since there was a good correlation between Iwe/Iwe + Iwh + Iap and weddellite/weddellite + whewellite + apatite that was determined by thermogravimetry (Fig. 1), the transformation rate of weddellite to whewellite can be expressed as the change of Iwe/Iwe + Iwh + Iap. One sample Iwe/Iwe + Iwh + Iap of which decreased by 48% in seven years (Fig. 3) and another sample Iwe/Iwe + Iwh + Iap of which increased by 10% in five years (Table) were excluded from this study because the clay films of these samples might have been overheated or incompletely dried before the first X-ray analysis.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D002129:Calcium Oxalate / Q000032:analysis*; D006801:Humans; D014545:Urinary Calculi / Q000032:analysis*; D014961:X-Ray Diffraction
chemical_list: C016189:whewellite; D002129:Calcium Oxalate