An optical sensing film was fabricated for sensitive determination of zinc ion in aqueous solutions. The optical sensor was prepared by synthesized ionophore, 5-Br salophen, dioctyl sebacate (DOS) as a plasticizer, sodium tetraphenyl borate (NaTPB) as a lipophilic anionic additive in a poly(vinyl chloride) membrane. The optode response is based on the cation-exchange membrane and indicated a significant absorbance signal change on the exposure to Britton-Robinson buffer solution of pH 5.7 containing Zn2+ ion. The proposed sensor showed a linear range of 4.9 × 10-5-4.5 × 10-12 mol L-1 with a limit of detection of 3.9 × 10-12 mol L-1. Furthermore, satisfactory analytical sensing characteristics including selectivity, stability, and reproducibility for the determination of zinc ion were obtained. The response time of the sensing film was less than 5 min, depending on the concentration of Zn2+ ions. The proposed sensor was successfully applied for determination of zinc in tap water, river water, and sea water.
Keywords:
optical sensor; zinc ion; UV-Vis spectrophotometry; 5-Br salophen
