Construction and Characterization of Indium Liquid Ion Selective Electrodes Based on Crown Ethers in a PVC Matrix Membrane

Authors : Najwa I ABDULLA, AbdulMuhsin AlHAIDER

Pages : 687-696

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Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :Several indium ion selective electrodes were constructed based on 15-crown-5 insert ignore into journalissuearticles values(15C5);, dicyclohexano-18-crown-6 insert ignore into journalissuearticles values(DCH18C6); and dibenzo-24-crown-8 insert ignore into journalissuearticles values(DB24C8); as sensors and di-octyl phenyl phosphonate insert ignore into journalissuearticles values(DOPP);, di-butyl phthalate insert ignore into journalissuearticles values(DBPH);, tri-butyl phosphate insert ignore into journalissuearticles values(DBP);, tri-n-amyl phosphate insert ignore into journalissuearticles values(TAP); and bis insert ignore into journalissuearticles values(2-ethyl hexyl); phosphate insert ignore into journalissuearticles values(BEHP); as plasticizers in a PVC matrix membrane. Electrode parameters, pH effect and interferences were also studied. The indium electrode based on 15C5 using DOPP as a plasticizer gave the best response for low levels of In3+ ions. The linear range for this electrode ranged from 3.8 x 10-5 to 5.0 x 10-2 M insert ignore into journalissuearticles values(with correlation coefficient r = 0.9997);, the slope was 20.1 mV/decade with a detection limit of 1.2 x 10-5 M, and the working pH range was 3.8--5.9. Interferences of Na+ , K+ , NH4+ , Ca2+ , Ba2+ , Cd2+ , La3+ , Nd3+ and Eu3+ on the electrode response were also investigated using a mixed solution method. Mono- and divalent cations were found to interfere less than trivalent cations. The concentrations of indium ions in the prepared standard solutions were determined by direct, standard addition insert ignore into journalissuearticles values(SA);, multiple standard addition insert ignore into journalissuearticles values(MSA); and titration methods. The results were compared with those obtained by atomic absorption spectrophotometry. The precision and accuracy of each method were calculated and expressed in terms of the relative standard deviation and the relative error. Optical measurements were also studied by measuring the absorbance for each membrane after steady intervals of immersion in a standard solution of its ions using UV/Visible spectrophotometry. Each membrane showed a rapid decrease in absorbance when it reached the end of its life due to leaching of the membrane contents to the external solution.
Keywords : Indium electrodes, crown compounds, selectivity measurements, optode measurements