Discussion of reported work

Because most pharmaceutical active ingredients and excipients absorb NIR radiation, studies utilizing NIR may provide certain advantages over traditional methods of assay for blend homogeneity or complement the 

Pharmaceutical and medical applicatims of near-infrared spectroscopy 

The individual spectrum may be compared to a library of spectra that arise from previous homogenous blends. In this case, content uniformity is apparent when the spectrum or spectra collected from the current mixing is deemed similar to the library of spectra that represent previous homogenous blends. Any suitable algorithm for qualitative spectral identification would be appropriate for such calculations. 

Quantitative methods may be used to predict the homogeneity of the blend for the parameter(s) of interest based on the spectra. This approach varies from the quantitative analysis of spectra due to the fact that the regression model used to output predictions might 

The second and third means of collecting multiple spectra involve collection from numerous locations within the vessel at one or more times. Multiple spectra drawn at one time from various locations in a blender may be compared to themselves or to spectra collected at different times, with similarity indicating content uniformity. Parameters for comparison can again include common statistical factors such as standard deviation, relative standard deviation, variance, a host of indexes based on standard deviation, or the results from pattern recognition routines. Of course, spectra collected in this manner can also be compared to a library of spectra from previous homogenous blends. 

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