The determination of the degree of zinc complexation by chelating agents with differential pulse voltammetry

The degree of zinc complexation was related to the type of the chelating agent and to the pH, whereas the stability of the zinc complexes was examined according to the chelating agents chosen from the group of aminopolycarboxylates. The degree of zinc complexation by the chelating compounds of the aminopolycarboxylates [ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), N-(hydroxyethyl)ethylenediaminetriacetic acid (HEEDTA), nitrilotriacetic acid (NTA), S,S-ethylenediaminedisuccinic acid (S,S-EDDS), methylglycinediacetic acid (MGDA), glutamic acid diacetic acid (GLDA)] in the environment of the supporting electrolyte was determined by differential pulse voltammetry using a mercury electrode operating in the SMDE mode. Reference electrode was silver-chloride electrode and auxiliary electrode was glassy carbon electrode. Voltammetric researches were carried out on the AUTOLAB PGSTAT 12 (Eco Chemie - The Netherlands) with GPES software with the use of mercury electrode 663 VA Stand (Metrohm - Swiss). The degree of zinc complexation increased with the increase in the concentration of the chelating agent and with the rise in the pH. Zinc complexes with EDTA, HEEDTA, DTPA and S,S-EDDS preserved their stability with time elapsed.