A new NMR method for directly monitoring and quantifying the dissolution kinetics of starch in DMSO.
The kinetics of dissolution of starch is needed for (i) understanding digestive processes; (ii) providing data that could correlate with higher levels of starch structure; (iii) improving techniques for starch characterization in solution. A novel method is presented here to directly monitor these dissolution kinetics by time-resolved (1)H solution-state nuclear magnetic resonance (NMR); studies were carried out in deuterated dimethyl sulfoxide (DMSO-d(6)). By assuming pseudo-first-order kinetics with respect to starch concentration, the data for various starch samples yield values of the apparent rate coefficients for the rate of appearance of completely dissolved anhydroglucose units, results which have not been obtained hitherto. The presence of a limited amount of water in DMSO had a drastic effect on dissolution kinetics (slowing it down at high temperatures), indicating multiple pathways for the dissolution mechanism. Dynamic light scattering (DLS) appears to be more limited than the NMR method to monitor the kinetics of dissolution. The newly developed NMR method can be extended to other solvents and polysaccharides.
Dona
Anthony
A
Key Centre for Polymer Colloids, School of Chemistry F11, University of Sydney, NSW 2006, Australia.
Yuen
Chun-Wai Wayne
CW
Peate
Jonathan
J
Gilbert
Robert G
RG
Castignolles
Patrice
P
Gaborieau
Marianne
M
D002241:Carbohydrates / Q000737:chemistry*; D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D007700:Kinetics; D008027:Light; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D012275:Oryza / Q000378:metabolism; D012542:Scattering, Radiation; D013213:Starch; D013696:Temperature; D013997:Time Factors
D002241:Carbohydrates; D013213:Starch; D004121:Dimethyl Sulfoxide