Microchip Capillary Electrophoresis with an End-Channel Amperometric Detector and Its Preliminary Application

An end‐channel amperometric detector with a guide tube for working electrode was designed and integrated on a home‐made glass microchip. The guide tube was directly patterned and fabricated at the end of the detection reservoir, which made the fixation and alignment of working electrode relatively easy. The fabrication was carried out in a two‐step etching process. A 30 µm carbon fiber microdisk electrode and Pt cathode were also integrated onto the amperometric detector. The baseline separation of dopamine (DA), catechol (CA) and epinephrine (EP) was achieved within 80 s. Relative standard deviations of not more than 5.2% were obtained for both peak currents and migration times of DA and CA (n=5). Using standard adding method, DA in urine and plasma samples was detected. The recoveries were in the range of 83–103%.