Quantitative evaluation of indomethacin using probe-type Raman spectroscopy.

The heterogeneity of the sample governs the model design.

In this study, we conducted a quantitative evaluation of the indomethacin α/γ polymorphic mixed system using probe-type Raman spectroscopy. In mixed polymorphic systems, sample heterogeneity due to differences in crystal morphology and dispersion state is unavoidable, and in Raman spectroscopy, which involves local measurements, this can manifest as variability in quantitative values. In this study, we constructed multiple quantitative models with different sampling conditions and compared factor number dependency (PRESS) and quantitative performance indicators (R², SEC, SECV). As a result, it became clear that quantitative accuracy strongly depends not on differences in instrument performance, but on model design tailored to the desired accuracy and concentration range. This case illustrates that in the quantitative evaluation of crystalline polymorphs using probe-type Raman spectroscopy, it is not a matter of "whether it can be measured," but rather "how to design the model" that governs the results. Tech Analysis Co., Ltd. provides practical support that includes not only the optimization of measurement conditions but also analysis design and model construction.

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