Electrochemical Processes of Cadmium, Copper, Lead, and Zinc in the Presence ofN-(2-Hydroxyethyl)piperazine-N ′-3-Propanesulfonic Acid (HEPPS): Possible Implications in Speciation Studies

Abstract

The influence of N-(2-hydroxyethyl)piperazine-N ′-3-propanesulfonic acid (HEPPS) on the redox processes of cadmium, copper, lead and zinc was investigated by differential pulse anodic stripping voltammetry (DPASV), differential pulse polarography (DPP) and cyclic voltammetry (only for copper, lead and zinc). Depression of the metals peak current recorded by DPASV, DPP, and CV (only for copper and lead) were observed. HEPPS did neither complex cadmium or zinc nor modified the reversibility of the metals electrochemical DPASV and DPP (only for zinc) responses, but complexed copper and lead and modified the reversibility of the copper electrochemical DPASV and DPP responses, under the experimental conditions used. Stability constants for copper-HEPPS and lead-HEPPS systems were calculated by potentiometric titrations (pH measurements) using the SUPERQUAD computational program.