ABSTRACT
Objective To establish an innovative methods for the identification of nimodipine polymorphs. Methods Nimodipine of two crystal forms were prepared by rapid solvent removal and identified by powder X-ray diffraction, infrared spectroscopy and Raman spectroscopy.The dissolution study of the powder samples were carried out in six different mediums. Results Powder X-ray diffraction patterns of crystal form A and B could be used for the identification of crystal forms of nimodipine.Crystal form B has characteristic diffraction peaks at 2θ=5° and 2θ=13° in the pattern,while crystal form A has characteristic diffraction peaks at 2θ=27° distinguishing two crystal forms effectively. Raman spectrum could be used to identify the crystal forms.Compared with Raman spectra of crystal form B, there exists characteristic scattering peak at 500 cm-1 in crystal form A. According to the position and intensity of the peaks of crystal form A and B, it could distinguish two crystal types effectively.The results of dissolution tests showed that the solubility of crystal form A is better than crystal form B. Conclusion Various analysis techniques in different principle were used in the research, such as Powder X-ray diffraction, Infrared spectroscopy and Raman Spectroscopy etc.Crystal forms were confirmed in several aspects according to the properties of different crystal form, and the solubility of crystal form A is better than crystal form B.
ABSTRACT
Objective To establish an innovative methods for the identification of nimodipine polymorphs. Methods Nimodipine of two crystal forms were prepared by rapid solvent removal and identified by powder X-ray diffraction, infrared spectroscopy and Raman spectroscopy.The dissolution study of the powder samples were carried out in six different mediums. Results Powder X-ray diffraction patterns of crystal form A and B could be used for the identification of crystal forms of nimodipine.Crystal form B has characteristic diffraction peaks at 2θ=5° and 2θ=13° in the pattern,while crystal form A has characteristic diffraction peaks at 2θ=27° distinguishing two crystal forms effectively. Raman spectrum could be used to identify the crystal forms.Compared with Raman spectra of crystal form B, there exists characteristic scattering peak at 500 cm-1 in crystal form A. According to the position and intensity of the peaks of crystal form A and B, it could distinguish two crystal types effectively.The results of dissolution tests showed that the solubility of crystal form A is better than crystal form B. Conclusion Various analysis techniques in different principle were used in the research, such as Powder X-ray diffraction, Infrared spectroscopy and Raman Spectroscopy etc.Crystal forms were confirmed in several aspects according to the properties of different crystal form, and the solubility of crystal form A is better than crystal form B.
ABSTRACT
Objective:To study the molecular composition of bismuth potassium citrate. Methods:The content of bismuth was de-termined using a volumetric method, the content of potassium was determined by atomic absorption spectrometry, and the content of cit-rate root was determined by ion chromatography. The structure was predicted using 1 HNMR and the crystal structure was studied using X-diffraction test and scanning electron microscopy. The changes in the percentage ratio of the three components were investigated by accelerated stability tests. Results:On the dried basis, the percentage of the three molecular components was bismuth of 35%-38%, potassium of 7%-11% and root citrate of 49%-52%. The NMR spectra and the data indicated that the product had three isomers with the molecular structure of bismuth∶potassium∶root citrate=2∶2∶2. The X-diffraction test and SEM showed that the three forms of amor-phous, monocrystalline and polycrystalline might exist. The percentage ratio of the three elements before and after the stability test was basically stable. Conclusion:Bismuth potassium citrate may have three crystal forms with the percentage of the three structure parts within a certain range, and the structure is relatively stable.