Research on molecular dynamics of sucrose hydrolysis process based on mid-infrared evanescent wave absorption spectroscopy technology.

This work develops a high-sensitivity mid-infrared evanescent wave (MIR-EWs) sensing platform based on tellurium chalcogenide tapered fibers. A spatial optical coupling system enables efficient light coupling between the mid-infrared source and the fiber, while tapered chalcogenide fibers strengthen the interaction between the evanescent field and liquid analytes. Label-free and derivatization-free, the platform achieves precise discrimination of glucose (1030 cm-1) and fructose (1060 cm-1) structural isomers. Within 0-2 mol/L, the linear correlation coefficient exceeds 0.98 with negligible cross-interference in mixed-component quantification. Utilizing the 998 cm-1 characteristic peak of sucrose α-1,2-glycosidic bonds, in-situ continuous monitoring of acid-catalyzed hydrolysis is realized. Pseudo-first-order kinetics is accurately identified at high substrate concentrations, with a rate constant of 3.37 × 10-4 min-1. The sensor presents outstanding stability: the repeatability relative standard deviation (RSD) is below 0.4%, temperature-induced RSD within 15-50 °C is less than 0.64%, and stable performance is maintained across pH 1.1-7.2 with an RSD under 0.11% after over 500 min of continuous operation. Combined with the partial least squares regression model, the prediction determination coefficient of sucrose hydrolysis conversion reaches 0.987, with a root mean square error of only 3.60%. This work offers a novel route for in-situ kinetic analysis of liquid-phase reactions and provides a cost-effective, reliable strategy for multicomponent quantification and dynamic monitoring of complex organic systems.