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Solid State Characterization of Sodium Eritadenate

American Journal of Analytical Chemistry 2011年第2期2卷 164-173页

作者： Josefine Enman Anuttam Patra Kerstin Ramser Ulrika Rova kris arvid berglund Department of Chemical Engineering and Geosciences Lulea University of Technology Department of Computer Science and Electrical Engineering Lulea University of Technology

Knowledge of the solid state is of great importance in the development of a new active pharmaceutical ingredient, since the solid form often dictates the properties and performance of the drug. In the present study, solid state characteristics of the sodium salt of the candidate cholesterol reducing compound eritadenine, 2(R), 3(R))-dihydroxy-4-(9-adenyl)-butanoic acid, were investigated. The compound was crystallized by slow cooling from water and various aqueous ethanol solutions, at different temperatures. Further, the compound solution was subjected to lyophilization and to high vacuum drying. The resulting solids were screened for polymorphism by micro Raman spectroscopy (λex = 830 nm) and the crystallinity was investigated by X-ray powder diffraction. Further, thermal analysis was applied to study possible occurrence of solvates or hydrates. Solids obtained from slow cooling showed crystallinity, whereas rapid cooling gave rise to more amorphous solids. Analysis of difference spectra of the Raman data for solids obtained from slow cooling of solution revealed subtle differences in the structures between crystals derived from pure water and crystals derived from aqueous ethanol solutions. Finally, from the thermal analysis it was deduced that crystals obtained from pure water were stoichiometrically dihydrates whereas crystals obtained from aqueous ethanol solutions were 2.5 hydrates;this formation of different hydrates were supported by the Raman difference analysis.

关键词： Sodium Eritadenate Solid state Chemistry Raman Spectroscopy Thermal Analysis Crystal Hydrates Polymorphism

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Pyranine Fluorescence Quenching for the Characterization of Solutions

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American Journal of Analytical Chemistry 2016年第1期7卷 43-56页

作者： Qiuxia Wang kris A. berglund Departments of Chemical Engineering & Materials Science Michigan State University East Lansing MI USA Departments of Chemistry Michigan State University East Lansing MI USA Departments of Food Science & Human Nutrition Michigan State University East Lansing MI USA Division of Chemical Engineering Lulea University of Technology Lulea Sweden

Fluorescence quenching of pyranine by tryptophan, phenylalanine, and nicotinic acid was investigated by using steady state and time resolved fluorescence spectroscopy. On a comparative basis, nicotinic acid is a very strong quencher of pyranine fluorescence, tryptophan is a moderate quencher and phenylalanine is a weak quencher. The strong quenching is the result of the hydrogen bonding complex between pyranine and amine which existed in both tryptophan and nicotinic acid. Contact complex will form between phenylalanine and pyranine which is the reason of quenching of pyranine by phenylalanine. Associates will form in tryptophan and phenylalanine due to the zwitterion +H3NRCOO- or/and hydrogen bond. Higher concentrations favor the formation of aggregates in the supersaturated solution which made the quenching curve different from unsaturated solution dramatically.

关键词： Fluorescence Quenching Pyranine Solution Structure Tryptophan

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