Polymorphism confirmation

Comparing experimental values (labeled G in Figure 9) and calculated values (labeled H) for all three polymorphs confirms the assumption... 

The Li-Zn phase diagram shows the presence of eight intermediate phases. Later x-ray diffraction results confirm the existence of five intermediate RT phases " . Polymorphism is shown by the three compounds shown in the Li-Cd phase system, and this has confused the interpretation of x-ray diffraction patterns ". 

Further confirmation that the HCN polymorphism is a general phenomenon came from the work of a colleague at the University of British Columbia, Fred Ganders (1990), who studied white clover from six sites in southwestern British Columbia and adjacent Washington. In all but one of the sites (the exception being a particularly... 

Three laboratories in addition to NIST participated in an inter-laboratory evaluation of the CHR template. All of the laboratories essentially followed the NIST protocol. Three of the four labs found essentially the same polymorphisms. Laboratory 4, who had less experience with sequencing mtDNA, did find differences that the other laboratories did not observe. The differences noted by Laboratory 4 confirm and emphasize the need for a standard reference material for sequencing mtDNA. Had Laboratory 4 had run NIST mtDNA SRM 2392 simultaneously with their unknown sample, they would have realized that they were finding an undue number of differences and could have reexamined their procedures to try to determine the reason for these differences. 

Table 7 shows the calculated weight percent of calcium carbonate and titanium dioxide in the white-colored paint sample. These levels are based on the calcium and titanium levels shown in Table 6. Calcium carbonate was evident by the FTIR spectrum acquired from the dried paint sample, shown in Figure 13. (Flad it been available, Raman spectroscopy, which gives ready access to the low wavenumber region, could have been used to confirm the presence (and polymorphic form) of titanium dioxide [4].) Given the white color of the paint, it is likely that the titanium present was present as titanium dioxide, and this was assumed in the calculations. The calculated weight percentage of calcium carbonate in the dried paint is 21.7 wt%, and 12.6 wt% in the paint containing the solvents. The titanium dioxide levels were calculated to be 30.6 and 17.7 wt% in the dried and solvent-containing paint sample, respectively.

Two polymorphs of (/q-penicillaminc are known [2], with the existence of these being confirmed using infrared spectroscopy and X-ray crystallography. It was reported that Form I has a minimum between its IR peaks at 1078 and 1101 cm-1 that are less intense than the adjacent peaks at about 1050 and 1160 cm-1, while Form II has an absorption peak at 1092 cm-1 which is more intense than the adjacent peaks at about 1050 and 10160 cm 1 [2],... 

A rate enhancement effect due to secondary nucleation has been identified in the solution-mediated transformation of the 7-phase of (i)-glutamic acid to its / -phase [82]. In this study, the kinetics of the polymorphic transition were studied using optical microscopy combined with Fourier transform infrared, Raman, and ultraviolet absorption spectroscopies. The crystallization process of n-hexatriacontane was investigated using micro-IR methodology, where it was confirmed that single... 

Polymorphisms of the beta adrenergic receptors have also been studied in patients with heart failure and cardiomyopathy, or other complex and rather ill-defined phenotypes. In patients with heart failure due to ischemic or idiopathic dilated cardiomyopathy, the Thrl64Ile polymorphism in the />2-adrerioreceplor was significantly associated with survival rate at one year [62]. Similarly, the Ser49Gly polymorphism of the /Vadrenoreceptor gene has been linked to the improved survival of patients with idiopathic cardiomyopathy [63]. However, sample size was limited in those studies and results need to be confirmed in adequately powered studies. 

Ulrich CM, Bigler J, Velicer CM et al. Searching expressed sequence tag databases discovery and confirmation of a common polymorphism in the thymidylate synthase gene. Cancer Epidemiol Biomarkers Prev 2000 9 1381-1385. 

As mentioned before, fosinopril sodium is known to be capable of existing in two polymorphic forms, and the diffuse reflectance IR spectra of the two forms indicated that the two structures differed in the conformation of one sidechain. The solid state 13C NMR spectra obtained on both forms were found to confirm this hypothesis [19]. As may be seen in Fig. 3, the significant spectral differences were all associated with nuclei contained within the acetal sidechain. 

The primary method for demonstration of the existence of drug polymorphs, or solvate species, is that of powder x-ray diffraction (XRD). Such measurements represent a specification of the internal structure within a crystal, and an evaluation of its lattice type. Since dissolution and subsequent drying can sometimes yield an undesired structure, it is also important to confirm crystal structures at each formulation stage during the beginning of the development process. 

In the case of DuP747 [24], XRD, DSC, and thermomicroscopic studies determined the polymorphic system to be monotropic. Distinct diffuse reflectance IR, Raman, and solid state 13C NMR spectra existed for each physical form. The complementary nature of IR and Raman gave evidence that the polymorphic pair were roughly equivalent in conformation. It was concluded that the polymorphic character of DuP 747 resulted from different modes of packing. Further crystallographic information is required in order to determine the crystal packing and molecular confirmation of this polymorphic system. 

---