The in-situ solid-state NMR spectroscopy investigation of alcoholic lactose suspensions

The polymorphic forms of lactose in alcoholic suspensions have been determined by 13C CP-MAS NMR spectroscopy, employing hand-made glass inserts. Suspensions of alpha lactose monohydrate (Lα·H 2O) with particle size between 2 and 200 μm were prepared by 24 h reflux or by storage for 28 d in anhydrou...

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Bibliographic Details
Published in:Solid state nuclear magnetic resonance 2010-05, Vol.37 (3), p.75-81
Main Authors: Crisp, J.L., Dann, S.E., Edgar, M., Blatchford, C.G.
Format: Article
Language:English
Subjects:
Alcohols - chemistry
Lactose - chemistry
Magnetic Resonance Spectroscopy
Solvents - chemistry
Surface Properties
Suspensions
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Summary:The polymorphic forms of lactose in alcoholic suspensions have been determined by 13C CP-MAS NMR spectroscopy, employing hand-made glass inserts. Suspensions of alpha lactose monohydrate (Lα·H 2O) with particle size between 2 and 200 μm were prepared by 24 h reflux or by storage for 28 d in anhydrous ethanol without agitation. These suspensions were compared to an ethanolic sub-micron lactose suspension provided by a 3 M Health Care (Loughborough). The 13C CP-MAS NMR spectra indicated that Lα·H 2O dehydrated to stable anhydrous alpha lactose polymorph (Lα S) whilst suspended in ethanol. In addition, strong ethanol 13C resonances were observed for some samples, indicating a liquid–solid interaction between the ethanol and lactose surface. Replacement of ethanol with anhydrous methanol, n-butanol and 3-methylbutan-2-ol implied that the solvent mediated dehydration of Lα·H 2O to Lα S occurs as a result of sterically controlled interactions.
ISSN:0926-2040
1527-3326
DOI:10.1016/j.ssnmr.2010.05.001