Iodide–Selective Electrodes Based on Two New Carriers: Influence of Various Nanoparticle Materials on the Response Performance of proposed electrodes

Abstract

The influence of various nanoparticles such as oxidized multiwall carbon nanotubes (MWCNTs), silver, zinc sulfide and zinc selenide loaded on the active carbon on the response properties of new iodide carbon paste electrodes based on bis(3-phenyl-2-propenaldehydene)-1,3-propanediamine zinc(II) chloride, [ZnL1Cl2] and bis(4-nitrobenzylidene) ethylenediamine mercury(II)bromide [HgL2Br2] as suitable carriers are described. It was seen, for both ionophores among different nanoparticle, the best response (wide linear range and low detection limit) was observed in the presence of oxidized MWCNT. The effects of various parameters such as amount of ionophores, amount of additive and role and amount of nanoparticles on the response properties of proposed electrodes were investigated. Amount of oxidized multiwall carbon nanotube (MWCNT), additives (MTOACl), ionophores and Nujol were optimized and their values are set as: carbon powder, oxidized MWCNT: Nujol, Carrier: MTOACl (0.15 g, 12 mg, 50 mg, 27 mg, 21.2 mg) and (0.15g, 8 mg, 50 mg, 20 mg, 10 mg) for [ZnL1Cl2] and [HgL2Br2], respectively. The electrodes based on [ZnL1Cl2] and [HgL2Br2] complexes exhibits Nernstian slope of 57.3 ± 1.2 and 59.8 ± 0.8 mV per decade over a wide concentration range from 1.0×10-6 to 1.0×10-1 and 1.0×10-7 to 1.0×10-1 M with detection limit of 8.8×10.-7 and 7.5×10.-8 M. They have relatively fast response times (20 s and 15 s), satisfactory reproducibility (±1.2 and ±0.8) and relatively long life times (2 months). The proposed sensors show high selectivity toward iodide ion in comparison to other common anions, while there potentiometric responses are independent of the solution pH in the pH of 2.5–11.0. The proposed electrodes especially based on mercury complex in the presence of oxidized MWCNT show very unique selectivity and low detection limits. They were used successfully as indicator electrodes in potentiometric titration and direct determination of iodide content in drug containing compound.