A self-catalytic carbon paste electrode for the detection of vitamin B12

A simple, sensitive, and selective method for the detection of vitamin B-12 (cyanocobalamin) is presented. A carbon paste electrode has been constructed with trans-1,2-dibromocyclohexane (DBCH) acting as both the paste binder and a reactive material facilitating the electrocatalytic detection of the target. The latter reaction is based on the electroreduction of the Co(III) center in vitamin B-12 to Co(I), which specifically reacts with DBCH to produce electrocatalytic currents with the regeneration of Co (II); a detection limit of 8.5 x 10(-10) mol dm(-3) (based on 3sigma) was found. The electrode has been successfully used for the quantification of Vitamin B-12 in pharmaceutical products and biological matrix media.