A Modified Carbon Paste Sensor for Determination of Zn in Vitamin and Waste Water using Thiosemicarbazide and Acetaldehyde Thiosemicarbazone Complexes

Abstract

A novel carbon paste Zinc (II) ion-chemically modified carbon paste sensors highly selective and sensitive (CMCPE) based on the metal complexes Zn- incorporating thiosemicarbazide, [Zn(TS)2(ac)2]. C2H5OH (Zn-TSC) and Zn-acetaldehyde thiosemicarbazone [Zn(ATS)2]. 4H2O (Zn-ATSC) dissolved in tricresyl phthalate (TCP) as binder liquid. The chemically modified sensors were developed for determination of Zinc (II) in vitamin and waste water. The constructed sensors showed good linear response of Nernstian slopes 32.5 ± 0.5 and 28.5 ± 0.5 mV per decade over the concentration range of 5.0×10-8-2.0×10-3 and 6.3×10-8 - 7.9×10-3 M with a detection limit of 0.25 and 0.50 nM for (Zn-TSC) and (Zn-ATSC) ions respectively. The selectivity coefficients of the proposed sensors revealed very good selectivity with respect to alkali, alkaline earth and some transition metal ions and could be used in pH range of 3.5-8.0. As a result the proposed sensors were successfully applied to (Zn- TSC) or (Zn- ATSC) ions determination in mixture solutions, multivitamins and wastewater samples and as an indicator sensors for potentiometric titration of Zn2+ with EDTA. The isolated complexes, (Zn- TSC) or (Zn- ATSC) were synthesized by the anodic dissolution of Zinc metal in an anhydrous acetone solution of the ligands where TSC is thiosemicarbazide, ATSC is acetaldehyde thiosemicarbazone ligand and ac = acetone. Applications of the proposed sensors to the determination of zinc as an indicator sensor for potentiometric titration of Zinc (II) ion with EDTA are successfully applied. The obtained results were compared using the US Pharmacopeia method and there is no significant difference was observed.