Biomedical Engineering Reference
In-Depth Information
Fig. 10.8.
PCA scores plot from a freeze-drying process of mannitol, a solution
monitored by in-line Raman spectroscopy [52]. Copyright by American Chemical
Society
et al. performed 3D Raman mapping in a fluidised bed to study the distri-
bution of a poloxamer glass bead mixture [51]. The authors also discuss the
potential of solid-state determination using Raman to obtain physical informa-
tion in 3D within a fluidised bed. Tumuluri et al. used Raman spectroscopy to
investigate hot-melt extruded films [10]. Quantitative in-line measurements of
the content of clotrimazole and ketoprofen in films were reported. In addition,
off-line determination of solid-state form of ketoprofen indicated a transition
from the API during the hot-melt extrusion procedure. De Beer et al. [52]
and Romero-Torres et al. [53] demonstrated the use of in-line Raman spec-
troscopy for monitoring of freeze-drying of mannitol solutions. Both groups
could show the potential for Raman monitoring of physical state changes
during the freeze-drying process. Figure 10.8 shows mannitol crystallisation
during freeze-drying as measured with Raman spectroscopy [52]. Wikstrom
et al. reported on online monitoring of content uniformity of acetaminophen
tablets and discussed sampling statistics of batch characterisation [54].
In addition to the small number of in-line applications reported in the lit-
erature, many off-line applications of Raman spectroscopy reported show the
potential for in-line use of Raman spectroscopy in a manufacturing environ-
ment. Folestad et al. reviewed the role a Raman spectroscopy in secondary
manufacturing and discussed potential applications in terms of pharmaceu-
tical unit operations [20]. Results were shown for content uniformity of a
tabletting process, Fig. 10.9. Williams et al. used FT-Raman spectroscopy
to gain understanding of granulation, tabletting and storage processes and
to assess crystalline hydrochloride form versus amorphous free base of the
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