Clotrimazole-Triiodide Ion Association as an Ion Exchanger for a Triiodide Ion-Selective Electrode

Abstract

There has been continuing growth in the number of PVC membrane electrodes that have been prepared for a variety of substances. These electrodes can be prepared by incorporating any of the many ion-exchanger or neutral-sequestering agents within a plasticized PVC matrix, and used as very useful tools for clinical, chemical and environmental analysis. 1 and Schiff-base complexes 6 have been reported as possessing improved characteristics in selectivity. Despite an urgent need for a triiodide-selective sensor for a direct determination of iodine or an indirect determination of some important specific oxidizing substances in many industrial, medical and environmental samples, there has been limited reports on a triiodide ion-selective electrode in the literature. 7,8We recently studied the electrochemical behavior and some chemical properties of various antifungal drugs containing piperazine or imidazole groups such as, ketoconazole in aqueous and non-aqueous media. [9][10][11][12] In this work, we initially studied the reaction between clotrimazole (CT) (a drug containing an imidazole ring) and triiodide ions. We found that the protonated clotrimazole (CTH + ) is precipitated in the presence of excess I3 -ions as a (CTH)I3 ion pair. Since the obtained ion pair is very stable and insoluble in aqueous solutions, we therefore employed this ion pair to prepare a new solvent polymeric membrane sensor for selective monitoring of the I3 -ion. Applications of the proposed membrane electrode as an indicator electrode in the potentiometric titration of triiodide ions in solutions and in the indirect potentiometric determination of CT from pharmaceutical preparations were investigated. Experimental Reagents and chemicalsReagent-grade benzyl acetate (BA), 2-nitrophenyl octyl ether (NPOE), nitrobenzene (NB), acetophenone (AP), bis(2-ethyl hexyl) sebacate (DOS), tetrahydrofuran (THF), chloroform and high relative molecular-weight PVC were purchased from Aldrich and used as received. Reagent-grade CT, oleic acid (OA), tetraphenyl phosphonium chloride (TPPC), iodine and all of the anionic salts used (all from Merck) were of the highest purity available, and were used without any further purification. Aqueous solutions were prepared by dissolving the appropriate salt or diluting standard solutions as specified in doubly distilled water. ApparatusA WTW multilab 540 Ionalyzer (Germany) pH/mV meter was used for the potential and pH measurements at 25.0 ± 0.1˚C. The cell used was of the type Ag/AgCl, KCl (3 M) | internal solution KI3 (0.01 M) | PVC membrane | test solution | Ag/AgCl, KCl (3 M). The activities of anions were calculated using the Debye-Hückel procedure. 13 An LKB Model 4054 UV-Vis recording spectrophotometer with 10 mm quartz cells was used for absorbance measurements. Preparation of ion-exchanger (CTH)I3To a 10 ml aliquot of a 0.01 M aqueous CT solution containing a few drops of HCl (1 M) was slowly added a triiodide solution (0.01 M) with continuous stirring until precipitation was completed. The resulting brown ion-pa...

Novel triiodide ion-selective polymeric membrane electrodes based on some transition metal–Schiff base complexes

“…Despite the need for the determination of triiodide in indirect evaluation of concentration of some important oxidizing substances; there have been limited reports on the applicability of triiodide ISEs. To the best of our knowledge, there are only nine reports available for triiodide ion selective electrodes (ISEs) [14][15][16][17][18][19][20][21][22][23]. The first triiodide ISE based on manganese (III) tetraphenyl porphyrine was reported in 1993 [14].…”

Charge-Transfer Triiodide Ion-Selective Electrode Based on 7,16-Dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane

“…Among different anion carriers used for this purpose, 4 the use of metalloporphyrins, [5][6][7][8][9][10] metal complexes, 11,12 and organometalic compounds 13,14 as ionophores in solvent polymeric membrane electrodes are well known to induce potentiometric anion selectivity sequences that differ significantly from the classical Hofmeister pattern. [5][6][7][8][9][10][11][12][13][14] Despite the need for a triiodide ion-selective electrode for the determination of iodide and triiodide ion in many medical, 17,18 juice (as ascorbic acid in orange juice) 20 and environmental samples (such as dissolved O2 in water), [15][16][17][18][19][20][21][22][23] to date there have been limited reports on an I3 -ion-selective electrode in the literature. [17][18][19]22,23 Furthermore, it is interesting to note that, to the best of our knowledge, there is one literature report concerning the use of charge-transfer complexes of crown ethers for preparing an ion-selective electrode.…”

“…[5][6][7][8][9][10][11][12][13][14] Despite the need for a triiodide ion-selective electrode for the determination of iodide and triiodide ion in many medical, 17,18 juice (as ascorbic acid in orange juice) 20 and environmental samples (such as dissolved O2 in water), [15][16][17][18][19][20][21][22][23] to date there have been limited reports on an I3 -ion-selective electrode in the literature. [17][18][19]22,23 Furthermore, it is interesting to note that, to the best of our knowledge, there is one literature report concerning the use of charge-transfer complexes of crown ethers for preparing an ion-selective electrode. 23 In this article, we report on a highly selective PVC-based membrane sensor for the I3 -anion based on a charge-transfer complex between iodine and 7,16-dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecan (DBZDA18C6), formulated as (DBZDA18C6·I + )I3 -, as suitable sensing material.…”

Sequential Flow Injection Determination of Chlorine Species Using a Triiodide-selective Electrode Detector

“…24,36 In the present work, we applied this membrane as a triiodide flow-through detector, which enabled the speciation of CAC, TAC, FAC and chlorite to be conducted. Although other triiodide selective electrodes using ionophores [37][38][39][40][41][42][43] have been reported, the blank PVC membrane is preferred due to its simplicity in preparation and its economy.…”