Infrared hyperspectral imaging for qualitative analysis of pharmaceutical solid forms

A multi-spectral imaging spectrometer records simultaneously spectra and spatial information of samples. The infrared (IR) imaging system used was the Hyperion 3000 microscope (Bruker Optics) equipped with a focal plane array (FPA) detector. The detector allows creating a 64 × 64 pixels image. For each pixel, a complete spectrum is acquired, which means that an IR image is in fact a data cube. Two methods for qualitative analyses of the data cube were applied: peak height and unfold principal component analysis (PCA). These methods were performed on two different pharmaceutical problems: the first one was the analysis of a contamination on the surface of a pharmaceutical solid dosage form and the second one was a set of six images of intact tablets with different dissolution properties. On the first data set, IR imaging and chemometrics identified the contamination (a concentration of wet dye). The imaging method applied on the second set allowed the determination of the main cause of the dissolution problem, which was the surface distribution of magnesium stearate. This study shows that infrared imaging can be useful for qualitative analysis and troubleshooting of pharmaceutical solid forms.