Determination of the free metal Ion concentration using AGNES Implemented with environmentally friendly bismuth film electrodes
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Ex-situ plated Bi film electrodes (Bi-FE) have been employed, for the first time, to measure the free concentration of Pb(II) in aqueous solutions using AGNES (Absence of Gradients and Nernstian Equilibrium Stripping) with Stripping Chronopotentiometry (SCP) quantification. The amount of deposited Pbº,
below a certain threshold, follows a Nernstian relationship with the applied potential. This threshold can be interpreted as the frontier of transition from surface deposition to solid (bulk) formation of Pbº. AGNES with Bi-FE yielded a very good detection limit (3σ) for Pb(II) of 6.0×10-9 M with an applied gain of 398 and a deposition time of 400 s. The ability of the Bi film electrode to perform speciation measurements was demonstrated for Pb(II)-PSS and Pb(II)-IDA systems. The measured values with the Bi-FE were in good agreement with the values obtained using the Hg film electrode and/or the values reported in the literature.