Sulfite determination at in situ plated copper modified gold ultramicroelectrode arrays

The electroanalytical detection of sulfite has been explored at an in situ formed copper ultramicroelectrode arrays. The protocol is based upon the in situ deposition of copper at a gold ultramicroelectrode array of cubic geometry which consists of 256 ultramicroelectrodes which are 5 microns in radius and are separated from their nearest neighbor by 100 microns. The immobilized copper array is electrocatalytic for the electrochemical reduction of sulfur dioxide which is formed after protonation of sulfite at low pH values (< pH 2). A sensitivity and detection limit of 0.35 nA mu M-1 and 6 mu M respectively is shown to be possible in pH 2.5 using linear sweep voltammetrv with a linear range observed from 20-500 mu M.