DEVELOPMENT AND CHARACTERIZATION OF A NEW COBALT OPTICAL SENSOR BASED ON INCORPORATTING OF SALOPHEN IN A PVC MATRIX

Abstract

A new optical sensor is described for determination of cobalt ions. The optode membrane is based on interaction of salophen (N,N’-bis (salicylidene)-o-phenylenediamine) with cobalt ions in plasticized polyvinyl chloride (PVC) membrane, supported on a glass plate. In the fabricated optode, salophen acts as sensing component. Color of the sensing membrane in contact with. Co2+ ions al pH 5.4, was changed from yellow to orange. The membrane composition and other affecting variables were optimized. Under the optimum conditions (i.e. 29.1 % PVC, 63.1 % DOS, 3.9% NaTPB, 7.8% salophen and response time of 5 min.), the proposed sensor displayed a linear range of 0.1-10 µg mL-1 with a detection limit of 0.016 µg mL-1. Also the precision (RSD %) was better than 1.34% for 7 replicate determinations of 2.5 µg mL-1cobalt (II) in various membranes. The sensor showed good selectivity for Co2+ ions with respect to several common al kali, alkaline earth and transition metal ions. The proposed optode was used for determination of Co2+ ions in water samples.