- Measurement of lactose crystallinity using Raman spectroscopy. BM Murphy, SW Prescott and I Larson. Journal of Pharmaceutical and Biomedical Analysis, 38(1), 186–190, 2005.
Abstract:
Raman spectroscopy (RS) was used to determine the crystallinity of
lactose (a commonly used carrier in dry powder inhaler (DPI) formulations).
Samples of alpha-lactose monohydrate and amorphous lactose were
prepared using ethanol precipitation and lyophilisation respectively.
The anomeric forms were confirmed using DSC at a rate of 10 °C/min
and heated to 250 °C. The Raman spectra of both alpha-lactose monohydrate
and amorphous lactose were obtained. Distinguishable differences
were seen between the two spectra including peak areas and intensities.
Depolarisation ratios (rho) of each form were then determined
to identify the crystallinity of the lactose carrier samples. At
the prominent Raman bands 865 and 1082 cm-1, significant differences
in rho values were observed for crystalline (0.80 ± 0.07, 0.89
± 0.06 respectively) and amorphous samples (0.44 ± 0.07, 0.51 ± 0.10)
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