Ratiometric fluorescent monitoring of methanol in biodiesel by using an ESIPT-based flavonoid probe

Abstract

Developing an analytical method for monitoring methanol content in biodiesel in a rapid and precise manner is of great importance for biodiesel production quality control, due to that an excessive amount of methanol in biodiesel will accelerate the engine aging thereby affect driving safety. In this study, we reported a novel flavonoid-based fluorescent probe HOF with the excited-state intramolecular proton transfer (ESIPT) character. This study demonstrated that the alcohols could form strong intermolecular hydrogen bonds with the HOF molecules and consequently block the ESIPT process, triggering a fast and specific fluorescence response. This alcohol-sensing method was proven to be rapid, sensitive, ratiometric, and visually discernible for detection of methanol with multi-channel signal output (fluorescent wavelength, intensity, and lifetime). Moreover, this method was successfully applied for determination of methanol content in commercial biodiesel, which may provide a practical tool for real-time monitoring of biodiesel production process.