Amperometric detection in microchip electrophoresis devices: effect of electrode material and alignment on analytical performance.

The fabrication and evaluation of different electrode materials and electrode alignments for microchip electrophoresis with electrochemical detection is described. The influences of electrode material, both metal and carbon-based, on sensitivity and LOD were examined. In addition, the effects of working electrode alignment on analytical performance (in terms of peak shape, resolution, sensitivity, and LOD) were directly compared. Using dopamine (DA), norepinephrine, and catechol (CAT) as test analytes, it was found that pyrolyzed photoresist electrodes with end-channel alignment yielded the lowest LOD (35 nM for DA). In addition to being easier to implement, end-channel alignment also offered better analytical performance than off-channel alignment for the detection of all three analytes. In-channel electrode alignment resulted in a 3.6-fold reduction in peak skew and reduced peak tailing by a factor of 2.1 for CAT in comparison to end-channel alignment.