Enhancement of sensitivity of electrochemical heavy metal detection by evaporative concentration using a super-hydrophobic surface

A novel method to concentrate a droplet of a sample solution on a chip evaporatively and improve the sensitivity for electrochemical heavy metal detection was developed. The chip consisted of a working electrode and a Ag/AgCl reference electrode surrounded by a super-hydrophobic surface. When a droplet of an aqueous solution placed on the area was evaporated, it shrank to the sensitive area making contact with the sensitive area. This effectively concentrated the analyte heavy metal ions. Anodic stripping voltammetry was conducted using the system and the technique. To analyze various heavy metal ions, a bismuth or gold electrode was used as the working electrode. A significant increase in peak height was observed by the evaporative concentration, and the effect was enhanced as the volume of the solution increased and the area of the sensitive area decreased.