Determinations polyvinylpyrrolidone

It is surprising to note that for all four columns there is good agreement between the M determined in water and in water/methanol, despite the fact that PEO and polyvinylpyrrolidone have different hydrodynamic volumes in these two mobile phases and that the column packings may swell or shrink differently in these two mobile phases. 

An early example of Raman mapping by Breitenbach et al. [52] showed that when crystalline ibuprofen is formulated in a hot melt extrudate the API changes to the amorphous form. Ibuprofen is a sparingly water-soluble compound, so this formulation provides a route to better bioavailability via the more soluble amorphous form. Using confocal Raman mapping the form of the API was determined at the time of manufacture and under stress conditions and was used to assess the stability of the amorphous form. These studies also showed that the API was homogeneously distributed throughout the formulation based on the relative band intensities of the amorphous API and a formulation excipient, polyvinylpyrrolidone (PVP). 

FIGURE 7.6 Determination of the intrinsic viscosity of polyvinylpyrrolidone in 70% isopropyl alcohol at 23 °C. 

G 3 — Weight average molecular weight of polyvinylpyrrolidone preparations as determinated by light scattering. J. Phann. and Pharmacol. 9,230 (1957). 

Structural or geometric isomers as well as nearly identical molecules may be discriminated by NIR. Some early work was performed by Kradjel and Ciurczak and presented in 1985. Work has been performed where the type of polyvinylpyrrolidone is determined by NIR. The only differences between types are polymerization conditions. 

Faulkner A, DeMontigny P. High-performance liquid chromatographic determination of denatonium benzoate in ethanol with 5 % polyvinylpyrrolidone. / Chromatogr-A 1995 715(1) 189-194. Henderson MC, Neumann CM, Buhler DR. Analysis of denatonium benzoate in Oregon consumer products by HPLC. Chemo-sphere 1998 36(1) 203-210. 

As the description of the nitrogen determination in the povidone (and crospovidone) monographs included in Ph.Eur. 5 and in USP26 is not exact enough to obtain always a complete degradation of the polyvinylpyrrolidone polymer a modified Ph.Eur. method is given here ... 

The most important and clearest method of identification is by infrared spectroscopy. The same method can be used for all the types of crospovidone. Figure 72 shows this infrared spectrum. The only disadvantage of this method of identification is that soluble polyvinylpyrrolidone (povidone) gives the same infrared spectrum (see Section 2.3.1.1, Fig. 24). However, the difference can readily be determined from the solubility. 

Most of the colour and precipitation reactions described in the literature for soluble polyvinylpyrrolidone can be used in the qualitative determination of copovidone (Table 160). 

Laser-source confocal Raman spectroscopy was used to analyze solid dispersions to evaluate the physical properties and determine the distribution of ibuprofen in extrudates of polyvinylpyrrolidone (PVP). As is shown in Figure 14, a shift in the Raman spectra occurs when the crystalline form of ibuprofen is compared to a solution or a PVP extrudate containing ibuprofen. For comparison purposes, ibuprofen was completely dissolved in dimeric... 

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