Evaluation of nanometer thick mercury film electrodes for stripping chronopotentiometry

Abstract

In this work, the performance and applicability of the thin mercury film electrode (TMFE) in the heavy metal speciation, by stripping chronopotentiometry (SCP), were exploited. The TMFE thickness was optimized and a 7.6 nm mercury film was selected. This TMFE was mechanically stable and able to perform 60 SCP consecutive measurements, with no significant variation in the analytical signal of lead(II) (RSD less than 2%). Due to the small electrode thickness the measurements were performed under conditions of complete depletion over a wide oxidation current (I s ) range, i.e., within the interval [75-500] · 10 À9 A. The limit of detection (3r) for lead(II) was 2.4 · 10 À9 M for a deposition time of 40 s and an oxidation current of 75 · 10 À9 A. The TMFE was successfully applied to the construction of SSCP experimental waves, which were in conformity to those predicted by the theory. The stability constant calculated (K 0 ) for the Pb(II)-carboxylated latex nanospheres system using a TMFE, agreed with the one obtained using the HMDE, for identical experimental conditions.

A review on electrochemical methods for trace metal speciation in environmental media

“…Typical deposition times are of the order of 45-180s, so that an SSCP curve requires between 20 min and 1h. [75] Depends on free concentration, on lability of complexes and on the size of the electrode. In the worst scenario, when complexes do not contribute at all, with HMDE, a rough rule is a deposition time (in seconds) 7 times the gain (Y) [101].…”

Toxicokinetics and tissue distribution of cadmium-based Quantum Dots in the marine mussel Mytilus galloprovincialis

“…The free Cd ion (Cd 2þ ) and total labile Cd concentrations in seawater from control and exposure groups were determined by Absence of Gradients and Nernstian Equilibrium Stripping (AGNES) and Stripping Chronopotentiometry (SCP) techniques using Eco Chemie mAutolab III potentiostat, Metrohm 663VA stand, GPES 4.9 software (Eco Chemie) and disposable polystyrene cups (VWR 611-1366) in order to avoid losses to the container walls according to Rocha et al (2007) and Domingos et al (2011). The following parameters were used for AGNES analysis: initial purge time 600 s, deposition potential À0.705 V, deposition time 240 s, stripping current 4 mA.…”

Bioavailability of cadmium and biochemical responses on the freshwater bivalve Corbicula fluminea – the role of TiO2 nanoparticles

“…An EcoChemie μAutolab III potentiostat/galvanostat (Metrohm Autolab B.V.; The Netherlands) was used in conjunction with a Metrohm 663 VA stand and a personal computer using the GPES 4.9 software (EcoChemie). A Ag/AgCl reference electrode with a 0.1 M NaNO 3 salt bridge, a glassy carbon counter electrode and a thin mercury film electrode (TMFE, working electrode) plated onto a rotating glassy carbon disc (1.9 mm diameter; Metrohm, The Netherlands) (Rocha et al, 2007) were used. All Cd þ nTiO 2 containing exposure solutions were purged with nitrogen for 20 min prior to measurements which were carried out at room temperature (20 1C).…”