Novel erbium (III)-selective fluorimetric bulk optode

For the first time a highly sensitive and selective fluorimetric optode membrane was prepared for the determination of trace amounts of Er(III) ions. The Er(III) sensing system was constructed by incorporating 5-(dimethylamino) naphthalene-1-sulfonyl-4-phenylsemicarbazide (L) as a neutral Er(III)-selective fluoroionophore, in the plasticized PVC-membrane containing sodium tetraphenyl borate as a lipophilic anionic additive. The response of the optode is based on the strong fluorescence quenching of L by Er3+ ions. At a pH value of 5.0, the proposed optode displays a wide concentration range of 1.0 × 10−10 to 1.0 × 10−2 M, with a relatively fast response time of less than 50 s. In addition, to high stability and reproducibility, the sensor shows a unique selectivity towards Er3+ ion with respect to common cations. The proposed optode was applied successfully to the trace determination of erbium ion in binary mixture and water samples.