Determination of Hg(II) in natural waters using a carbon paste electrode modified with hybrid mesostructured silica nanoparticles

Mesostructured silica nanoparticles functionalized with a 5-mercapto-1-methyltetrazole derivative (MTTZ-MSU-2) were employed to prepare a chemically modified carbon paste electrode for Hg(II) determination in aqueous media by square wave adsorptive anodic stripping voltammetry. Under optimized operating conditions, 60 s of electrolysis time in HCl 0.1 M, the voltammetric signal increased with increasing preconcentration time from 1 to 10 min. The voltammetric responses measured (peak areas) were linear with respect to Hg(II) concentration in the range of 0.1–1 μM with a detection limit of 0.099 μM after 5 min preconcentration time and in the range of 0.025–0.25 μM with a detection limit of 0.023 μM for 10 min of preconcentration time. The chemically modified carbon paste electrode had good single and inter-electrode reproducibility (RSD of 2 and 12%, respectively). Applicability to spiked groundwater and river water was demonstrated without any sample pretreatment (recoveries of 99 and 92%, RSD 4–7%, respectively).