Three-Layer Electrospray Constructing Charged Microdroplets for Online Derivatization and Position Identification of Lipid CC Bonds

Numerous studies have demonstrated that charged microdroplets can significantly accelerate chemical reactions. In this work, we developed a novel three-layer electrospray ionization source (TL-ESI). This source generated charged microdroplets capable of facilitating the rapid epoxidation of unsaturated lipid CC bonds with the derivatization reagent 3-chloroperbenzoic acid (m-CPBA) in an online process, achieving a conversion rate of up to 92.8%a performance not achievable with conventional electrospray ionization source (ESI). Compared to conventional ESI, the TL-ESI effectively compartmentalized reactants, enabled precise control over the reaction process, and supported rapid online derivatization of lipid CC bonds with m-CPBA. When integrated with tandem mass spectrometry (MS/MS), this source further enabled the localization of lipid CC bond positions. The TL-ESI is characterized by its simplicity in design, ease of operation, and seamless integration with mass spectrometry (MS). These advantages make it an efficient and practical tool for locating CC bond positions in unsaturated lipids, even within complex sample matrices. Additionally, this work highlights the potential of the TL-ESI as an innovative platform for accelerating chemical reactions via charged microdroplets, offering a valuable addition to the toolbox of modern analytical chemistry.