The electroanalytical detection of sulfite has been explored at an in situ formed copper ultramicroelectrode array. 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 (
