Novel selective optode membrane for terbium ion based on fluorescence quenching of the 2-(5-(dimethylamino) naphthalen-1-ylsulfonyl)-N-henylhydrazinecarbothioamid

For the first time, a highly sensitive and selective fluorimetric optode membrane sensor for determination of trace amounts of Tb(III) ions was prepared. The Tb(III) sensing system was prepared by incorporating 2-(5-(dimethylamino) naphthalen-1-ylsulfonyl)-N-phenylhydrazinecarbothioamide (L) as a neutral Tb(III)-selective fluoroionophore, in the plasticized PVC membrane containing sodium tetraphenyl borate as a liphophilic anionic additive. The response of the sensor is based on the strong fluorescence quenching of L by Tb(III) ions. At pH 4.7, the proposed sensor displays a calibration curve over a wide concentration range of 1.0 × 10−2 to 1.0 × 10−8 M, with a relatively fast response time of less than 1 min, high stability, high reproducibility and a relatively long working lifetime. The sensor shows a good selectivity towards Tb(III) ion respect to all lanthanide and common coexisting cations. The proposed fluorescence optode was applied successfully to determination of Tb(III) ion in water and phosphate rock samples.