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 Cu(II) can be detected using FSCAV in different matrices. We find that matrices with different Cu(II) binding ability do not affect the equilibrium of Cu(II) adsorption onto CFMs, and thus are an excellent predictor for free Cu(II) ([Cu(II)]free) in solution. We modelled a correlation between the FSCV response, [Cu(II)]free and logKf for 15 different Cu(II) complexes. Using our model, we rapidly predicted, and verified [Cu(II)]free and Kf of a real groundwater sample spiked with Cu(II). We thus highlight the potential of fast voltammetry as a rapid trace metal speciation sensor. To read the rest of the article click here.