Detection of trace amounts of Hg2+ in different real samples based on immobilization of novel unsymmetrical tetradentate Schiff base within PVC membrane

Abstract

A novel fluorescence optical sensor for sensitive and selective determination of Hg2+ ions in aqueous solution has been prepared. The sensing system is made of a novel unsymmetrical tetradentate Schiff base namely N-(2-hydroxyphenyl)-N′-(2-mercaptophenyl)-o-phthalylidene (HMP), as a neutral Hg2+-selective fluoroionophore immobilized in a plasticized PVC membrane containing potassium tetrakis-(4-chlorophenyl) borate (KTpClPB) as a lipophilic anionic additive. The response of the optode is based on the strong fluorescence enhancement of HMP upon exposure to Hg2+ ions. Under the optimum conditions, the proposed sensor displays a linear response in concentration range of 2.27×10−11 to 1.13×10−3mol/L, with a detection limit of 9.57×10−12mol/L. Furthermore, the proposed optode displays a good selectivity toward Hg2+ ions in comparison with common coexisting cations. The sensor was applied successfully for determination of mercury ions in different real samples.