LAUSR

The value of double potential pulse differential techniques for electrochemical studies of dynamic chemical speciation is investigated within the context of liquid|liquid electrochemistry. Then, not only information about the speciation thermodynamics and kinetics is accessible, but also about the species lipophilicity. This provides a comprehensive view of their behaviour in natural and biological media. With the above aim, the current-potential response of the ACDT mechanism (aqueous complexation-dissociation coupled to transfer), where two chemically linked species can transfer between a hydrophilic and a lipophilic phase, is modelled in differential double pulse voltammetry (DDPV) and additive differential pulse voltammetry (ADPV). Explicit closed-form expressions are deduced for both techniques at liquid|liquid macrointerfaces, applicable to any charge number and lipophilicity of the species. The DDPV and ADPV signals are shown to be well sensitive to the features of the chemical reaction, as well as to the species charge and lipophilic character. Also, these techniques offer higher resolution and discrimination against superimposed signals than direct-current techniques, together with high sensitivity and minimization of capacitive effects and background currents, which are key advantages for accurate quantitative analysis.