Exploring the Crystallinity of Different Powder Sugars Through Solid Echo and Magic Sandwich Echo Sequences.

Time domain NMR (TD-NMR) techniques are frequently used in polymer, pharmaceutical and food industries as they offer rapid experimentation and generally do not require any considerable preliminary sample preparation. Detection of solid and liquid fractions in a sample is possible with the Free Induction Decay (FID). However, for the classical FID sequence that consists of a single pulse followed by relaxation decay acquisition, the dead time of the probe (ring-out of resonance circuitry) occurs and varies between 5-15 μs for standard 10 mm tubes. In such a case, there arises a risk that the signal from the solid fraction cannot be detected correctly. To obtain quantitative measurement on crystalline and more mobile amorphous fractions, alternative sequences to the classical FID in the solid-state NMR were developed. Solid echo (SE) and Magic Sandwich Echo (MSE) sequences perform the relaxation decay refocusing somehow excluding the dead time problem and allow detection of the signal from the solid fraction. In this study, knowledge of amorphous/crystal fraction, which is obtained through SE and MSE has been explored on powder sugar samples for the purpose of developing a groundwork for a reliable quality control method. Different sugars were examined for the utilization of the sequences. What is important to add and make this study unique is that the method proposed did not involve multiparameter fitting of the 'bead' pattern FID signal that normally suffers from ambiguity; just the integration of the FFT of the solid echo was needed to calculate the second moment, (M2 ).