Low‐field nuclear magnetic resonance relaxometry: a new approach for monosaccharide identification in sugar solutions

Abstract

SummaryMonosaccharides such as glucose, fructose, and galactose are the building blocks of oligosaccharides and act as the major energy sources in our body. These three monosaccharides are the most prominent in food processing and widely consumed analytes, found in fruits or milk. Although several analytical methods are available to identify and quantify sugar solutions, their drawbacks urge the search for better possible alternatives. A simple, rapid, and efficient method for identifying monosaccharides (ᴅ‐fructose, ᴅ‐galactose, and ᴅ‐glucose) was investigated using low‐field nuclear magnetic resonance (LF‐NMR), exploring the applicability and reliability of this machine. The transverse (T2) relaxation curve was analysed to distinguish monosaccharides from each other. The increasing monosaccharide concentration in the sugar solution causes leftward shifts in signals, indicating a gradual reduction in the mobility of water molecules. The addition of sugar generated a secondary peak, which assisted in identifying monosaccharides. Notably, fructose exhibited distinct behaviour from that of glucose and galactose. The regression coefficient consistently exceeded 0.98, indicating the reliability of this experiment. LF‐NMR encountered challenges in differentiating stereo‐isomeric glucose and galactose. However, quantification of monosaccharides from known binary mixtures (water and one monosaccharide) is possible by preparing standard curves of different concentrations of sugars. These standard curves can be either T2 or the total surface area of the peaks as a function of sugar concentration. The study concludes that LF‐NMR has potential for the qualitative and quantitative analysis of monosaccharides in pure solutions or powdered samples. It is hoped that the rapid and easy way of monosaccharide identification by simple analysis of peaks obtained from NMR spectra will enhance its accessibility for users. However, it also acknowledges limitations in applying this method to complex systems (mixtures of different sugars in a solution).