Fitting of the beat pattern observed in NMR free-induction decay signals of concentrated carbohydrate-water solutions.
A series of mathematical functions has been used to fit the proton free-induction decays (FIDs) of concentrated carbohydrate-water samples. For the solid protons, these functions included a sinc function, as well as the Fourier transforms of single and multiple Pake functions multiplied by a Gaussian broadening. The NMR signal from the mobile protons is described by an exponential function. It is found that in most cases the sinc function gives a satisfactory result and provides valuable information about the second moment M(2) and the ratio of solid to mobile protons (f(s) / f(m)). A good indication for using the sinc function is the presence of a beat in the FID. For high temperatures this approach breaks down, and a biexponential fit is more appropriate. If a clear dipolar splitting is observable in the NMR spectra, the Pake function (or a multiple Pake fit) should be used. In this case information about M(2) and f(s) / f(m) can also be obtained.
Derbyshire
W
W
Division of Food Sciences, School of Biological Sciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LEICS, LE12 5RD, UK.
Van Den Bosch
M
M
Van Dusschoten
D
D
MacNaughtan
W
W
Farhat
I A
IA
Hemminga
M A
MA
Mitchell
J R
JR
D000465:Algorithms; D002241:Carbohydrates / Q000032:analysis / Q000737:chemistry*; D003201:Computers; D005583:Fourier Analysis; D005947:Glucose / Q000032:analysis / Q000737:chemistry; D046911:Macromolecular Substances; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008358:Mannose / Q000032:analysis / Q000737:chemistry; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D009991:Oscillometry / Q000379:methods*; D014867:Water / Q000032:analysis / Q000737:chemistry*
D002241:Carbohydrates; D046911:Macromolecular Substances; D014867:Water; D005947:Glucose; D008358:Mannose