Versatile Procedures for Reliable NMR Quantification of CO2 Electroreduction Products

Electrochemical reduction can capture and utilize CO2 through its conversion to small chemicals and fuels. Analytical standard operating procedures for the accurate quantification of short-chain acids, aldehydes, and alcohols by high-performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC-MS), or NMR are not well established. Electrochemical reduction of CO2 produces the smallest conceivable organic compounds, which necessitates slow NMR quantifications due to slow T1 relaxation toward equilibrium magnetization. It is shown that the use of paramagnetic contrast agents or cooling of water/DMSO provides T1-optimized measurements with attractive sensitivity and speed. 1H NMR experiments that are widely used in the study of biological mixtures are found unsuitable for quantitative analyses of T1-optimized samples.