Saeid Ahmadzadeh - Pharmaceutics Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, Iran.
Anoushirvan Mohseni-Bandpei - Department of Environmental Health Engineering, School of Public Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Somayeh Badakhshan - Department of Environmental Health Engineering, School of Public Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Majid Aghasi - Department of Environmental Health, School of Public Health, Kerman University of Medical Sciences, Kerman, Iran.

The increasing use of ion sensors in the fields of environmental, agricultural and medicinal analysis is stimulating environmental chemists to develop new sensors for the fast, accurate, reproducible and selective determination of various species. In the past decade, considerable efforts have led to the development of selective sensors for alkali, alkaline earth and heavy metals. In the current work the amount of membrane compositions including benzo-18-crown-6 as an ionophore (4 mg), PVC (30 mg), 2-nitrophenyl octyl ether (o-NPOE) as a plasticizer (65 mg) and sodium tetra phenyl borate (NaTPB) as a lipophilic additive (1 mg) were optimized. The fabricated sensor revealed nrenstian slope of 17.85 ± 0.52 (mV per decade of activity) over the pH range from 2.5 to 5.5 with a satisfactory concentration range of 1.0×10−6 to 1.0×10−1 M. The developed sensor revealed acceptable repeatability with a fast response time of 25 seconds over a period of about 3 months. The effects of various parameters such as composition of the membrane, different cation interferences and concentration of internal solution were investigated. The fabricated sensor was used successfully for direct determination of iron (III) content of tab water samples and the obtained results were validated by atomic absorption spectrometry (AAS).

Fe (III) Sensor; Potentiometry; Benzo-18-crown-6; PVC membrane