Evaluation of nanometer thick mercury film electrodes for stripping chronopotentiometry

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 (Is) range, i.e., within the interval [75–500] × 10−9 A. The limit of detection (3σ) for lead(II) was 2.4 × 10−9 M for a deposition time of 40 s and an oxidation current of 75 × 10−9 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′) for the Pb(II)-carboxylated latex nanospheres system using a TMFE, agreed with the one obtained using the HMDE, for identical experimental conditions.