A pharmaceutical active compound, chloramphenicol palmitate, appears in three polymorphic forms, that can be observed at room temperature.The stable form A (biologically inactive modification), the meta-stable form B (active modification) and unstable form C were found to have distinct Raman spectra, with bands attributable to the different polymorphs.The use of hot-stage Raman microscopy (the direct coupling of Raman microscopy and hot-stage) is demonstrated for the drug substance chloramphenicol palmitate form C. All modifications of form C were produced and identified by hot-stage Raman microscopy. A close correlation of thermal and spectroscopic information was achieved by this combination of techniques.As reported in several pharmacopoeias, the content of form A should be less than 10%; therefore, a mixture of 10% (w/w) A in B was prepared, and the presence of the characteristic bands of form A after subtraction of the pure B was revealed. Moreover, mixtures between 2 and 12% (w/w) A in B were investigated and the intensity ratio (as peak area) I413–435/I1035–1158 as a function of A percentage has been demonstrated to show a linear trend. Other methods for the characterization of polymorphs were used: Fourier transform infrared spectroscopy (FT-IR), Diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), Differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD).
Solid state characterization of chloramphenicol palmitate. Raman spectroscopy applied to pharmaceutical polymorphs / Gamberini, Maria Cristina; Baraldi, Cecilia; A., Tinti; Rustichelli, Cecilia; Ferioli, Valeria; Gamberini, Gianfranco. - In: JOURNAL OF MOLECULAR STRUCTURE. - ISSN 0022-2860. - STAMPA. - 785:1-3(2006), pp. 216-224. [10.1016/j.molstruc.2005.10.012]
Solid state characterization of chloramphenicol palmitate. Raman spectroscopy applied to pharmaceutical polymorphs
GAMBERINI, Maria Cristina;BARALDI, Cecilia;RUSTICHELLI, Cecilia;FERIOLI, Valeria;GAMBERINI, Gianfranco
2006
Abstract
A pharmaceutical active compound, chloramphenicol palmitate, appears in three polymorphic forms, that can be observed at room temperature.The stable form A (biologically inactive modification), the meta-stable form B (active modification) and unstable form C were found to have distinct Raman spectra, with bands attributable to the different polymorphs.The use of hot-stage Raman microscopy (the direct coupling of Raman microscopy and hot-stage) is demonstrated for the drug substance chloramphenicol palmitate form C. All modifications of form C were produced and identified by hot-stage Raman microscopy. A close correlation of thermal and spectroscopic information was achieved by this combination of techniques.As reported in several pharmacopoeias, the content of form A should be less than 10%; therefore, a mixture of 10% (w/w) A in B was prepared, and the presence of the characteristic bands of form A after subtraction of the pure B was revealed. Moreover, mixtures between 2 and 12% (w/w) A in B were investigated and the intensity ratio (as peak area) I413–435/I1035–1158 as a function of A percentage has been demonstrated to show a linear trend. Other methods for the characterization of polymorphs were used: Fourier transform infrared spectroscopy (FT-IR), Diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), Differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD).File | Dimensione | Formato | |
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