Chemical image fusion. The synergy of FT-NIR and Raman mapping microscopy to enable a move complete visualization of pharmaceutical formulations

The pharmaceutical industry uses successfully both FTNIR and Raman microsco py to produce chemical images of solid dosage forms, typically in troublesh ooting roles. However, due to the chemical composition of the formulations, it is not always possible to describe the entire chemical formulation by us ing a single spectroscopic method. As Raman and NIR spectroscopies are comp lementary in nature, their combined usage offers the opportunity to describ e heterogeneous mixtures in more detail. A novel sample referencing approac h has been developed that allows data to be acquired from exactly the same area of the sample using both Raman and FT-NIR microscopies. The optimum im ages for the components are then overlaid, which gives rise to a combined c hemical image that visually describes the entire formulation. We have named this approach chemical image fusion (CIF). CIF has been applied to two exa mples. The first shows how a simple formulation was used to validate the CI F approach. In the second, CIF allowed an entire formulation to be visualiz ed and the cause of tabletting problems determined. CIF provides increased confidence in the results generated by each individual technique and offers a more powerful method for the evaluation of pharmaceutical formulations.