Novel fluorimetric bulk optode membrane based on a dansylamidopropyl pendant arm derivative of 1-aza-4,10-dothia-7-oxacyclododecane ([12]aneNS2O) for selective subnanomolar detection of Hg(II) ions

A novel fluorescence chemical sensor for the highly sensitive and selective determination of mercury(II) ions in aqueous solutions is prepared. The mercury sensing system was prepared by incorporating 1-(dansylamidopropyl)-1-aza-4,10-dithia-7-oxacyclododecane (L) as a neutral Hg2+ selective fluoroionophore in the plasticized PVC membrane containing potassium tetrakis(p-chlorophenyl)-borate as a liphophilic anionic additive. The response of the sensor is based on the strong fluorescence quenching of L by Hg2+ ions. At a pH 3.3, the proposed sensor displays a calibration curve over a wide concentration range of 1.0×10−4 to 5.0×10−12 M, with a relatively fast response time of less than 1 min. In addition to high stability and reproducibility, the sensor shows a unique selectivity towards Hg2+ ion with respect to common coexisting cations. The proposed fluorescence optode was applied to the determination of mercury content of amalgam alloy, hair and well water samples.