Quantification of monolaurin synthetically produced from Lauric acid and glycerin esterification: novel method via 1H NMR

Monolaurin (ML) is a monoglyceride naturally present in human breast milk, which exhibits beneficial results against pathogenic microorganisms, including various bacteria and viruses. Thus, given the importance of ML to prevent several diseases in newborn children, it is necessary to investigate efficient routes to produce it synthetically and to develop novel analytical methods to characterize it. This work focuses on the development of a method based on the quantitative 1 H Nuclear Magnetic Resonance Spectroscopy (q 1 H NMR), to approach the selectivity to ML produced through the acid-catalyzed esterification of LA with GL. Interestingly, the developed method is also capable to quantify the amount of dilaurin (DL) and eventually trilaurin (TL) coproduced in the synthesis of ML. From three replicated LA-GL esterification experiments carried out in batch over a commercial catalyst at the conditions: 3 mol/mol GL to LA, 150 °C, 5 g catalyst/100 g LA and 60 min, the q 1 H NMR results show that selectivity to ML, DL and TL amounts to 53.28 ± 2.05, 43.39 ± 2.0 and 1.33 ± 0.14 wt%, respectively, with variation coefficients below 10 %. These values are very close and exhibit a similar precision level compared to those obtained via chromatography coupled to mass spectrometry (GC–MS), i.e., 55.89 ± 1.60, 41.80 ± 1.45 and 1.09 ± 0.10 wt%, respectively. Moreover, the detection limit of the proposed q1H NMR method was found to be 0.4 mg/mL for ML. It is demonstrated that the q 1 H NMR is a nondestructive, low-cost, simple, efficient, high precision and reproducible technique for determining the selectivity to ML, DL and/or TL in the esterification of LA with GL, the precision of the reported method is comparable to that displayed by more sophisticated techniques such as GC–MS. • q 1 H NMR was able to quantify the selectivity to ML, DL and TL in the acid-catalyzed esterification of LA and GL. • q 1 H NMR is a non-destructive, efficient, and reproducible alternative technique to traditional methods like GC–MS. • q 1 H NMR produced reliable results with the coefficients of variation for selectivity below 10 %. • q 1 H NMR displayed precision levels for the selectivity to ML, DL and TL comparable to GC–MS • q 1 H NMR is a simple, low cost, and reproducible option to readily quantify products selectivity in chemical reactions.