The transesterification reaction used to produce biodiesel was monitored with 1H high-resolution nuclear magnetic resonance (HRNMR), conventional low-resolution NMR (LRNMR), and unilateral NMR (UNMR) spectroscopy. HRNMR was used as a standard method to compare with the methods of LRNMR and UNMR. A Carr–Purcell–Meiboom–Gill (CPMG) pulse sequence was used in both LRNMR and UNMR experiments. In LRNMR, the CPMG signal was used to measure the transverse relaxation time (T 2), which depended on sample viscosity; it showed a good correlation (R = 0.994) for the concentration of biodiesel in the oil/biodiesel mixture. These measurements could only be used when the samples contained less than 1% of methanol. In UNMR, the CPMG decay of the biodiesel/oil mixture strongly depended on molecular diffusion because of the intrinsic high magnet field gradient (G) associated with the magnetic. The T 2eff had a good and negative correlation (R = −0.997) with the biodiesel concentration in the biodiesel/oil mixture. The UNMR measurements were insensitive to the methanol contamination up to 50%, which was contrary to the LRNMR method. As methanol diffused rapidly, its magnetization lost coherency quickly in the presence of strong G and it was not fully refocused by the CPMG sequence. Therefore, the use of the fast, portable, and low cost UNMR sensor to monitor transesterification reactions was demonstrated ex situ. Now, the UNMR sensor has been adapted to monitor the transesterification reaction in situ, in a biodiesel pilot plant.

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As injury alters T2 values it is necessary to use intact bananas to study relaxation times during ripening. The novel interpretation for the increase in T(2vac) based on reduction of Fe+3 and O2 concentration is an alternative mechanism to that based on the hydrolysis of starch in amyloplasts.

Cassia ferruginea (Schrad.) DC. (Fabaceae) is a native plant widely used as an ornamental tree and for the restoration of degraded areas in Brazil. Although no previous ethnopharmacological or chemical information was available, bioprospecting studies on this species found out a high concentration of dihydromyricetin (DHM) in different parts of the plant. DHM, also known as (+)-ampelopsin, is a flavonoid that presents important pharmacological and biological activities, including anticancer, cardioprotective and hepatoprotective effects. The aim of this study was to develop and validate a simple method for the determination of DHM in hydroethanolic extracts of C. ferruginea by quantitative 1 H NMR (qHNMR) using the internal standard approach. The parameters as linearity, specificity and selectivity, accuracy, precision (repeatability and intermediate) and robustness showed satisfactory results. Five ethanolic extracts from different stages and organs of C. ferruginea were investigated, the DHM concentration ranges from 52.08 ± 3.95 to 201.83 ± 4.71 mg/g. The proposed method appears to be a suitable tool for fast quality control of herbal extracts, with no need of tedious sample preparation and chromatographic separations increasing the efficiency of natural products analysis. This is the first study reporting the presence and determination of DHM in Cassia ferruginea (Schrad.) DC.