Comparison of solid-state NMR and isothermal microcalorimetry in the assessment of the amorphous component of lactose

The aim of this study was to evaluate the use of solid-state nuclear magnetic resonance (NMR) in the assessment of the degree of disorder of processed lactose. The results obtained from 13C cross-polarisation/magic angle spinning NMR were compared with those obtained from isothermal heat-conductive...

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Bibliographic Details
Published in:International journal of pharmaceutics 1998-11, Vol.174 (1), p.243-252
Main Authors: Gustafsson, Christina, Lennholm, Helena, Iversen, Tommy, Nyström, Christer
Format: Article
Language:English
Subjects:
Analysis
Biological and medical sciences
Crystallinity
Disorder
General pharmacology
Isothermal microcalorimetry
Lactose
Medical sciences
Pharmacology. Drug treatments
PLS analysis
Solid-state NMR
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Summary:The aim of this study was to evaluate the use of solid-state nuclear magnetic resonance (NMR) in the assessment of the degree of disorder of processed lactose. The results obtained from 13C cross-polarisation/magic angle spinning NMR were compared with those obtained from isothermal heat-conductive microcalorimetry, in which the heat flow during crystallisation of the amorphous lactose in the samples was recorded. A series of lactose mixtures was prepared and studied. In agreement with earlier studies, the microcalorimetric analyses resulted in a linear relationship between heat flow and the nominal crystallinity of the lactose mixtures. Mathematical models established from NMR spectra accurately predicted results even when the lactose mixture contained an additional component, acetylsalicylic acid. The results obtained by microcalorimetry and solid-state NMR were in agreement. Both methods were very sensitive and could detect as low as 0.5% amorphous lactose in a mixture. In addition, solid-state NMR has the advantage of being able to provide structural information about a sample containing several different components.
ISSN:0378-5173
1873-3476
DOI:10.1016/S0378-5173(98)00272-5