Pharmaceutical Applications
Transmission Raman lends itself to rapid, non-invasive and non-destructive analysis of pharmaceutical dosage forms such as capsules and tablets. This addresses several limitations of traditional pharmaceutical assay techniques including limitations due to surface sensitivity (e.g., reflectance NIR), the presence of phase changes due to sample preparation (liquid chromatography) or sub-sampling (conventional Raman, NIR). Transmission Raman is largely insensitive to surface, requires no sample preparation, involves no phase change and is rapid. Transmission Raman spectroscopy of pharmaceutical tablets and capsules was first demonstrated by Matousek and Parker. Subsequent research established the technique’s accuracy and applicability to quantifying tablet and production-style capsule formulations.
Pharmaceutical tablets and capsules are typically composed of a combination of APIs and excipients, each of which will produce a Raman spectral component with a relative intensity proportional to the ingredient concentrations. Analysing Raman spectra to produce assay results requires a method to separate the individual spectral components and correlate their intensity contributions with a relative concentration measure. This is typically facilitated using chemometric analysis methods.
Transmission Raman spectroscopy can be used as a process analytical technology (PAT) tool for the detection of physical state of the API and for obtaining qualitative and quantitative information about the composition.
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