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Article Dans Une Revue Applied Spectroscopy Année : 2006

Water evaporation analysis of L-phenylalanine from initial aqueous solutions to powder state by vibrational spectroscopy

Résumé

The water evaporation from L-phenylalanine (L-phe) aqueous solutions at different initial pH (0-13) was studied by vibrational spectroscopy. Next, the attenuated total reflection-Fourier transform infrared (ATR-FT-IR) spectra of aqueous solutions were compared to those recorded after drying for 72 h at 21 °C at appropriate initial pH values. Micro-Raman results collected after the water evaporation process are also presented and interpreted. Between pH = 2.5 and 8.76 a white non-transparent gel was observed, possibly due to the presence of the NaCl salt. The significant differences of the band intensities of L-phe functional groups noticed at pH near pKa values indicate the structural changes of L-phe molecules due to dimer formation (hydrogen bonds between the -COOH and -CO2− groups, and the -NH3+ and -NH2 groups). The presence of the hydrophobic interactions leads to the aggregation of L-phe molecules, most probably via phe-phe stacking as well as complexes of phe with Na+ ions, HCl, or H2O molecules.
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Dates et versions

hal-00267840 , version 1 (28-03-2008)

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S. Olsztynska, N. Dupuy, L. Vrielynck, M. Komorowska. Water evaporation analysis of L-phenylalanine from initial aqueous solutions to powder state by vibrational spectroscopy. Applied Spectroscopy, 2006, 60, pp.1040-1053. ⟨10.1366/000370206778397425⟩. ⟨hal-00267840⟩

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