Sharp Absorption Peaks in THz Spectra Valuable for Crystal Quality Evaluation of Middle Molecular Weight Pharmaceuticals
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Middle molecular weight (MMW) pharmaceuticals (MW 400~4000) are attracting attention for their possible use in new medications. Sharp absorption peaks were observed in MMW pharmaceuticals at low temperatures by measuring with a high-resolution terahertz (THz) spectrometer. As examples, high-resolution THz spectra for amoxicillin trihydrate, atorvastatin calcium trihydrate, probucol, and α,β,γ,δ-tetrakis(1-methylpyridinium-4-yl)porphyrin p-toluenesulfonate (TMPyP) were obtained at 10 K. Typically observed as peaks with full width at half-height (FWHM) values as low as 5.639 GHz at 0.96492 THz in amoxicillin trihydrate and 8.857 GHz at 1.07974 THz for probucol, many sharp peaks of MMW pharmaceuticals could be observed. Such narrow absorption peaks enable evaluation of the crystal quality of MMW pharmaceuticals and afford sensitive detection of impurities.
KeywordsTerahertz spectroscopy High resolution and high accuracy Middle molecular weight pharmaceuticals Sharp absorption peaks
We thank Dr. Jun-ichi Nishizawa for his important suggestion about high-resolution THz spectroscopy.
This work was partly supported by Grants-in-Aid for Scientific Research (B) (No. 16H03882) from the Japan Society for the Promotion of Science.
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