Analytical Sciences
Online ISSN : 1348-2246
Print ISSN : 0910-6340
Original Papers
Preparation of a Clay-modified Carbon Paste Electrode Based on 2-Thiazoline-2-thiol-hexadecylammonium Sorption for Sensitive Determination of Mercury
Newton L. Dias FILHODevaney R. do CARMOFergus GESSNERAndré H. ROSA
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2005 Volume 21 Issue 11 Pages 1309-1316

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Abstract

A montmorillonite from Wyoming-USA was used to prepare an organo-clay complex, named 2-thiazoline-2-thiol-hexadecyltrimethylammonium-clay (TZT-HDTA-clay), for the purpose of the selective adsorption of the heavy metals ions and possible use as a chemically modified carbon paste electrode (CMCPE). Adsorption isotherms of Hg2+, Pb2+, Cd2+, Cu2+, and Zn2+ from aqueous solutions as a function of the pH were studied at 298 K. Conditions for quantitative retention and elution were established for each metal by batch and column methods. The organo-clay complex was very selective to Hg(II) in aqueous solution in which other metals and ions were also present. The accumulation voltammetry of Hg(II) was studied at a carbon paste electrode chemically modified with this material. The mercury response was evaluated with respect to the pH, electrode composition, preconcentration time, mercury concentration, “cleaning” solution, possible interferences and other variables. A carbon paste electrode modified by TZT-HDTA-clay showed two peaks: one cathodic peak at about 0.0 V and an anodic peak at 0.25 V, scanning the potential from -0.2 to 0.8 V (0.05 M KNO3 vs. Ag/AgCl). The anodic peak at 0.25 V presents excellent selectivity for Hg(II) ions in the presence of foreign ions. The detection limit was estimated as 0.1 µg L-1. The precision of determination was satisfactory for the respective concentration level.

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© 2005 by The Japan Society for Analytical Chemistry
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