Biomedical Engineering Reference
In-Depth Information
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Tablet
Fig. 10.9.
Raman monitoring of tablet content uniformity during tablet manufac-
turing
API [55]. Romero-Torres et al. used a revolving-focus Raman probe for whole
area sampling to characterise coating variations [56]. The authors discuss the
role of Raman versus NIR for coating applications and suggest the use of
Raman for coating concentration, sample weight increment and tablet disin-
tegration times. Kauffman et al. evaluated different multivariate approaches
for determining coating thickness in acetaminophen tablets [57] and found
target factor analysis to be a viable method. Several authors have addressed
the problem of sub-sampling in tablets. Jedvert et al. [58] and Johansson et
al. [16] used and investigated rotating tablet holders for extending the probed
surface. Kim et al. described the use of a wide area illumination probe for a
similar purpose for process applications [59]. Matousek et al. described the
concept Raman sampling in a transmission geometry for further enhanced
sampling volume [17] and Johansson et al. [19] presented quantitative aspects
and modelling of transmission Raman spectra of tablets and capsules. Trans-
mission Raman is the latest development for improved sampling volumes but is
presented in a separate chapter of this topic (Chap. 3 by Matousek et al.). Kim
et al. described the use of Raman spectroscopy for monitoring the content am-
broxol in intact capsules [60]. Kim et al. presented measurements of povidone
in solution through plastic bottles [61]. Recently, chemical imaging has been
proposed to present PAT opportunities [62].
10.4.3 Bioprocessing
Biopharmaceutics is a fast growing area with many new opportunities for the
pharmaceutical industry. Raman process monitoring has some great potential
in this field due to its compatibility with water, in contrast to, e.g. IR or THz
spectroscopy, although very little has been demonstrated so far. There are
also challenges to be considered such as significant fluorescence background
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