Near-infrared (NIR) spectroscopy has been shown to be a highly useful tool for analysis of pharmaceuticals. It can be used for many diverse industrial applications such as qualitative and quantitative analysis of powders, pellets, tablets, freeze-dried products, etc. Most notable advantages of NIR analysis are that the method is nondestructive, fast, and can be performed remotely; all this makes it especially useful for fabrication process analysis and quality control. In addition, the spectroscopic analysis of solids may offer probing of solid state properties such as crystallinity and sample density, parameters that are entirely lost by chromatography and other wet-chemistry methods.
In spite of all its advantages wide practical application of the NIR spectroscopy is hindered due to apparent difficulties one faces wile analyzing and quantifying the data. The problem is rooted in the fact that the light propagation in typical pharmaceutical tablet is heavily affected by the scattering and eventual absorption can not be directly related to active substance concentration and the sample geometry as in the case of classical spectroscopic experiment based on Beer-Lambert law. This generally necessitates evaluation of the NIR data on the basis of elaborated multivariate chemo-metric methods which prevents use of the NIR analysis in early stage of pharmaceutical product R&D and drastically raises the cost for its application in the fabrication process control.
In collaboration with AstaraZeneca, Biophotonics group at LLC undertakes a project aimed on development of new types of analytical instruments for NIR absorption spectroscopy. The powerful time-of-flight spectroscopic methods enable one to decouple scattering and chemical absorption contributions in NIR spectra of the pharmaceuticals. This strongly facilitates and simplifies the NIR data analysis and eventually leads to the decreased costs and widened application arias for the method in pharmaceutical industry.
Scatter correction of transmission NIR spectra by photon migration data: quantitative analysis of solids
C. Abrahamsson, S. Andersson-Engels, S. Svanberg, J. Johansson, S. Folestad Proceedings of the SPIE - The International Society for Optical Engineering, 6009 60090A-1-10 (2005)
Time-resolved NIR spectroscopy for quantitative analysis of intact pharmaceutical tablets
C. Abrahamsson, J. Johansson, S. Andersson-Engels S, et al. Analytical Chemistry 77 1055-1059 (2005)
Time and wavelength resolved spectroscopy of turbid media using light continuum generated in a crystal fiber
C. Abrahamsson, T. Svensson, S. Svanberg, S. Andersson-Engels, J. Johansson, S. Folestad, Optics Express, 12 4103-4112 (2004)
Time-resolved NIR/Vis spectroscopy for analysis of solids: Pharmaceutical tablets
Johansson J, Folestad S, Josefson M, et al. Applied Spectroscopy 56 725-731 (2002)