An integrated electrochemical capillary liquid chromatography-dual microelectrode system for bromine based reaction detection

Amperometric reaction detection of model peptides containing either a thiol or disulfide was successfully achieved with a novel coupled capillary liqu id chromatography-dual microelectrode system. Detection is facilitated via dual platinum wire electrodes fabricated directly on a liquid chromatograph y capillary column. The detection strategy is based on the electrogeneratio n of bromine at the upstream working electrode followed by reduction of the bromine to bromide at the downstream working electrode. When bromine react s with analyte eluting from the capillary column. the amount of bromine tha t reaches the downstream electrode decreases. As a result. the current at t he downstream electrode will decrease in proportion to the amount of analyt e eluting from the capillary column. Glutathione., glutathione disulfide, a lpha -TGF and oxytocin were used to characterize the system and to determin e system parameters. The feasibility of the determination of disulfide cont aining peptides is demonstrated with glutathione disulfide, alpha -TGF and oxytocin.