Visualization of Streams of Small Organic Molecules in Continuous-Flow Electrophoresis

Continuous-flow electrophoresis (CFE) separates a stream of a multi-component mixture into multiple streams of individual components inside a thin rectangular chamber. CFE will be able to benefit flow chemistry when it is capable of generically detecting streams of small organic molecules. Here we propose a general approach for molecular stream visualization via analyte-caused obstruction of excitation of a fluorescent layer underneath the separation chamber – fluorescent sublayer-based visualization (FSV). We designed and fabricated a CFE device with one side made of quartz and another side made of UV-absorbing visibly-fluorescent, chemically-inert, machinable plastic. This device was demonstrated to support non-aqueous CFE of small organic molecules and quantitative detection of their streams in real-time with a limit of detection below 100 µM. Thus, CFE may satisfy conditions required for its seamless integration with continuous flow organic synthesis in flow chemistry.