Microfluidic chip-based capillary electrophoresis system with integrated supported-liquid-membrane extraction-back-extraction sample pretreatment

This article presents the designing and fabrication of a microfluidic chip with an integrated supported-liquid-membrane extraction-back-extraction and chip-based capillary electrophoresis system (SLMEBE-CCE). A 3-dimensional channel network for the SLMEBE-CCE system was fabricated with a four-layer glass/FIFE-membrane hybrid structure. With a gravity pump for sample and back-extraction solution delivery and a multi-channel high-voltage supply for CCE separation, the microchip with the coupled SLMEBE-CCE system was demonstrated by the pre-concentration, separation and detection of a mixed solution of fluorescein and butyl-rhodamine B. Compared to chip-based CCE without SLMEBE, the developed SLMEBE-CCE system produced a 7-fold increase in the signal of the model analyte of fluorescein and a 4-fold decrease in the signal of the model co-existing compound of butyl-rhodamine B.