Coulometric Detection of Peptides by Reversed-Phase Liquid Chromatography Using an In-Line Reactor Containing Copper Metal

Abstract

A general method has been developed for the selective coulometric detection of peptides using reversed-phase liquid chromatography. This method is based on the formation of electrochemically oxidizable copper(II)-peptide complexes by the reaction of peptides with copper(II) ions in an alkaline mobile phase through an in-line reactor containing copper metal. Di-, tri- and tetrapeptides used as model compounds (6 species) are separated on a column containing C18- bonded vinyl alcohol copolymer gel (Asahipak ODP-50, 5μm, 150mm×6mm i.d.) and an alkaline mobile phase (pH 11.0, 25mM phosphate buffer). A detection limit of 3ng was obtained for alanylalanylalanylalanine.