Robust and simple interface for microchip electrophoresis–mass spectrometry

A robust and simple interface for microchip electrophoresis–mass spectrometry (MCE–MS) was developed using a spray nozzle connected to the exit of the separation channel of the microchip. The spray nozzle was attached to the microchip using a polyether ether ketone screw without adhesive, thus allowing easy replaced. Sample injection and electrophoretic separation was performed by control of the voltage only. The analysis of a few basic drugs was performed using the optimized MCE–MS system. The separation was improved by using a high-viscosity separation buffer and a spray nozzle with a small bore size. This system was also applied to the separation of peptides and protein–trypsin digests. Sample adsorption was minimized by adding acetonitrile to the separation buffer when using a quartz microchip.