eBook: Raman Imaging in Pharmaceutical Research - 5

chemical ingredients on its curved surface and within
a groove approximately 500 µm deep (Figure 1).
Quantitative Distribution Analysis of
Tablet Components
Figure 1. Topographic Raman image of a pharmaceutical tablet.
The Raman image is overlaid on the topography, revealing the distribution
of the tablet's ingredients on the curved sample surface and in the
approximately 500 µm deep groove: two different APIs (red and blue),
adjuvant (orange) and excipients (green and yellow). Scan area 7 x 7 mm².
A
B
Many drugs have a narrow therapeutic window, in
which an insufficient dose will not be therapeutically
effective, but an excessive dose will cause adverse
effects. Thus, a pharmaceutical tablet must contain
the correct dose of each component and this must
be precisely determined. From a Raman image, the
area fraction of each component can be quantified
C
D
E
Figure 2. Raman analysis of a painkiller tablet. The high-resolution, large-area Raman image of the tablet's surface (A) is color coded according to the Raman
spectra of the identified compounds (B): acetaminophen (blue), aspirin (purple), caffeine (red), magnesium stearate (yellow), starch (green), lactose (cyan). (1x1
mm² with 1000x1000 pixels.) From the individual Raman images (C), area fractions for each identified compound (D) and grain size distributions for lactose and
caffeine (E) were determined.
5

eBook: Raman Imaging in Pharmaceutical Research

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