Two-dimensional correlation in cyclic voltammetry and electrochemical quartz crystal microbalance: A complementary tool to conventional techniques

Two new chemometric electrochemical techniques based on generalized two-dimensional correlation are tested and validated. Two-dimensional cyclic voltammetry (2DCV) involves synchronous and asynchronous correlations between two identical sets of cyclic voltammograms; while correlation electrochemical quartz crystal microbalance (CEQCM) is a hybrid correlation between a set of charge vs. potential curves and a set of mass variation vs. potential curves. A model system with two Fe(III)/Fe(II) pairs is set up to evaluate the reliability and advantages of these two techniques. 2DCV analysis indicates that the charging of poly(vinyl ferrocene)/solution interface (non-faradic process) has a negative influence on the heterogeneous electron transfer (faradic process). CEQCM analysis clearly identifies which Fe(III)/Fe(II) pair is responsible for the mass variation of the poly(vinyl ferrocene) network. This is the first attempt that a two-dimensional correlation has been applied to electrochemical methods. We expect more electrochemical techniques will be expanded into two-dimensional analyses.