Correction of biased time domain NMR estimates of the solid content of partially crystallized systems

Abstract

The solid content values obtained from the intensity of the nuclear magnetic resonance free induction decay signal of partially crystallized samples such as fats, supersaturated solutions, solid dispersions of waxes, gels are biased due to the difference between the proton density and mass density of the samples. It is shown here that this can be easily corrected with the specific volumes (determined gravimetrically) and proton densities (determined by time-domain nuclear magnetic resonance) of completely liquefied models of the solid and liquid phases and provided that the total amount of crystallizable material is known. The corrected data are in excellent agreement with the values obtained by differential scanning calorimetry for both model systems and real petroleum samples.