Pharmaceutical Applications of Chemical Mapping and Imaging

Abstract

The sections in this article are Introduction The Technology and Rationale for Chemical Images Sample‐Preparation Considerations for Chemical Mapping and Imaging Chemical Mapping and Imaging Applications Polymorph Analysis Product Design and Development Product Performance and Support Chemical Image Production Using Chemometric Analysis The Hyperspectral Cube and Chemical Images Image Data Analysis Data Preprocessing Principal Component Analysis ( PCA ) Ordinary Least Squares ( OLS ) Partial Least Squares ( PLS ) PLS Quantitative Analysis PLS Classification Analysis of Chemical Images Conclusion Acknowledgments

Investigating the relationship between drug distribution in solid lipid matrices and dissolution behaviour using raman spectroscopy and mapping**Maike Windbergs and Miriam Haaser contributed equally to this work.

“…Near‐infrared (NIR), mid‐infrared (IR) and Raman microscopy have been used, and the data acquisition has involved point mapping, line mapping and global imaging. While global imaging has the advantage of speed, the mapping approaches provide rich spectral data which is important when analysing complex or poorly defined systems 8. The maximum spatial resolutions possible with NIR and IR radiation are approximately 6 µm8 and 4 µm, respectively,9 while in principle Raman microscopy may approach submicron levels 10.…”

“…While global imaging has the advantage of speed, the mapping approaches provide rich spectral data which is important when analysing complex or poorly defined systems 8. The maximum spatial resolutions possible with NIR and IR radiation are approximately 6 µm8 and 4 µm, respectively,9 while in principle Raman microscopy may approach submicron levels 10. NIR microscopy is characterised by a greater penetration depth than both Raman and IR microscopy (if the IR microscope is fitted with an attenuated total reflection [ATR] setup) 9.…”

Comparison of chemometric methods in the analysis of pharmaceuticals with hyperspectral Raman imaging

“…[26,27] The concentrations estimated by CLS usually differ from the real concentration values (the construction of reliable calibration samples is not possible in the case of unknown analytes); thus the terms 'spectral concentrations' and 'Raman score' will be used instead, to avoid confusion.…”

“…Although the relationship between these two are not clear without calibration, based on certain technology-based considerations a good estimation of the quantitative composition can be given based on the Raman CLS scores in the case of pharmaceuticals. [26] In addition, the relative standard deviation of the Raman scores is a quantitative measure of the homogeneity of an ingredient. [27] Thus, it was desirable to see how the statistical properties of the estimated Raman scores differ at the different chemometric methods.…”

Complementary Near‐Infrared and Raman Chemical Imaging of Pharmaceutical Thin Films

“…Raman spectroscopy may also be used in a confocal manner providing a depth profile of the sample. Overall, the two techniques offer many opportunities for the complementary characterization of pharmaceutical formulations 17–19…”