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Molecular exchange in thermal equilibrium between dissolved and crystalline tripalmitin by NMR
Author(s) -
Löfborg Negin,
Smith Paul,
Furó Istvan,
Bergenståhl Björn
Publication year - 2003
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-003-0840-8
Subject(s) - tripalmitin , chemistry , hydrogen–deuterium exchange , phase (matter) , solvent , analytical chemistry (journal) , chromatography , organic chemistry , mass spectrometry
An NMR technique to measure exchange kinetics at thermal equilibrium in dispersions of moderately soluble crystalline material is presented. By monitoring the exchange of molecules between pools in solid and dissolved form, one can characterize the surface specific exchange rate. Illustrative experiments were performed in a model system with β‐type crystals of tripalmitin as the solid phase and tripalmitin, a fraction of it deuterated, dissolved in a medium‐chain TG oil as the liquid phase. The concentration of deuterated tripalmitin in the solvent was followed by 2 H NMR after the crystals, which initially lack deuterated tripalmitin, were immersed in the liquid. The variation of the 2 H concentration in the solvent provided the surface specific exchange rate. No systematic errors, due to the slight difference in properties of the deuterated tripalmitin compared to hydrogenated tripalmitin, were observed. The methodology worked well between crystal concentrations of 2 and 4 wt%.