The in-situ solid-state NMR spectroscopy investigation of alcoholic lactose suspensions.
The polymorphic forms of lactose in alcoholic suspensions have been determined by (13)C CP-MAS NMR spectroscopy, employing hand-made glass inserts. Suspensions of alpha lactose monohydrate (Lalpha.H(2)O) with particle size between 2 and 200mum were prepared by 24h reflux or by storage for 28d in anhydrous ethanol without agitation. These suspensions were compared to an ethanolic sub-micron lactose suspension provided by a 3M Health Care (Loughborough). The (13)C CP-MAS NMR spectra indicated that Lalpha.H(2)O dehydrated to stable anhydrous alpha lactose polymorph (Lalpha(S)) whilst suspended in ethanol. In addition, strong ethanol (13)C 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 Lalpha.H(2)O to Lalpha(S) occurs as a result of sterically controlled interactions.
Crisp
J L
JL
Department of Chemistry, Loughborough University, Loughborough, Leicestershire LE11 3TU, UK.
Dann
S E
SE
Edgar
M
M
Blatchford
C G
CG
D000438:Alcohols / Q000737:chemistry*; D007785:Lactose / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D012997:Solvents / Q000737:chemistry; D013499:Surface Properties; D013535:Suspensions
D000438:Alcohols; D012997:Solvents; D013535:Suspensions; D007785:Lactose