Polymer microchip integrated with nano-electrospray tip for electrophoresis–mass spectrometry

A novel cyclo-olefin polymer (COP) microchip was developed integrated with an electrospray ionization (ESI) emitter tip for microchip electrophoretic separation and mass spectrometric detection. The microchip was fabricated by hot embossing and low-temperature direct bonding. The ESI emitter tip structure was formed directly at the microchip electrophoresis (MCE) outlet. Since these microchips enable negligible dead volume at the electrospray port, efficient spray of the sample necessary for acceptable resolution mass spectrometry (MS) was realized. Stable spray was also achieved at the low flow rate (∼0.1 μL/min) without additional pump. By applying the fabricated COP chip to the MCE–ESI-MS analysis, successful separation and detection of caffeine and arginine was achieved.