A Universal Roadmap for Quantification of Glycerol Electrooxidation Products Using Proton Nuclear Magnetic Spectroscopy (1H NMR)

The electrochemical oxidation of glycerol, a byproduct of biofuel production, can transform this low-value material into a range of valuable compounds to foster a circular bioeconomy. However, developing catalysts and unraveling the mechanisms behind glycerol oxidation hinge on the precise quantification of reaction products, a task requiring analytical techniques. Our research introduces proton nuclear magnetic spectroscopy (1H NMR) as a viable alternative to existing chromatographic and spectroscopic techniques, allowing a sensitive, rapid, and nondestructive detection and quantification of glycerol oxidation reaction products. Utilizing 1H NMR, we outline a comprehensive framework for identifying the products formed during glycerol oxidation with a focus on the chemical transformations that occur within the reaction medium. As a proof of concept, we employ a platinum catalyst for glycerol electro-oxidation in an alkaline electrolyte, specifically examining the influence of pH and identifying potential discrepancies in calculating Faradaic efficiencies for the reaction. Comparison of the results from 1H NMR with literature results obtained using high-performance liquid chromatography (HPLC) showed that both methods are coherent. To demonstrate the capabilities, a mixture containing known quantities of glycerol oxidation reaction products was analyzed by 1H NMR. Concentrations quantified by 1H NMR matched the real concentrations with an error margin of less than 8%, demonstrating the effectiveness of 1H NMR for the analysis of a complex mixture of species. These findings lay the groundwork for the broader integration of 1H NMR into complex liquid product analyses, particularly in organic mixtures.