Fast voltammetry of metals at carbon-fiber microelectrodes: towards an online speciation sensor

Speciation controls the chemical behavior of trace metals. Thus, there is great demand for rapid speciation analysis in a variety of fields. In this study, we describe the application of fast scan cyclic voltammetry (FSCV) and fast scan adsorption controlled voltammetry (FSCAV) to trace metal speciation analysis. We show that Cu2+ can be detected using FSCAV in different matrices. We find that matrices with different Cu2+ binding ability do not affect the equilibrium of Cu2+ adsorption onto CFMs, and thus are an excellent predictor for free Cu2+ ([Cu2+]free) in solution. We modelled a correlation between the FSCV response, [Cu2+]free and log Kf for 15 different Cu2+ complexes. Using our model, we rapidly predicted, and verified [Cu2+]free and Kf of a real groundwater sample spiked with Cu2+. We thus highlight the potential of fast voltammetry as a rapid trace metal speciation sensor.