Fabrication of a totally renewable off-channel amperometric platform for microchip electrophoresis

• A novel method to construct an off-channel based EC device is demonstrated.
• All electrodes used in this device can be easily regenerated.
• Microscopy is unnecessary in assembling of the PDMS chip and the EC device.
• A low background with a noise level of 1.4 pA (peak to peak) is achieved.
• The LOQ of dopamine and catechol can be down to sub-micro molar level.

In this approach, a novel method to fabricate an integrated amperometric platform used in off-channel electrophoresis has been introduced. A simple screen printed protocol combining a wet etching procedure was used to define the pattern on a glass substrate, and whole electrodes were constructed by filling the conductive carbon ink into the etched cavities. A simple Teflon tape was used to align this platform with the micro-channel, and the variation of reassembling of this device can be down to 2.2% without the assistance of microscope. This device was characterized by dopamine (DA) and catechol (CA), and the width of half peak is around 4 s, even a 100 μm double T shape injection design and a 550 μm working electrode were used in this work. Under the optimum condition, this device possesses a low background with a noise level of 1.4 pA (peak to peak). The linear range for DA and CA are 0.1–100 μM (R = 0.998) and 0.2–200 μM (R = 0.996) with a theoretical plate number of 1.57 × 104 and 3.46 × 104 (plate/m), respectively.

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