Development of a new fluorimetric bulk optode membrane based on 2,5-thiophenylbis(5- tert-butyl-1,3-benzexazole) for nickel(II) ions

Abstract

A highly sensitive and selective fluorimetric optode membrane for the determination of ultra trace amounts of Ni 2+ ions was prepared. The plasticized PVC-membrane incorporating potassium tetrakis( p-chlorophenyl)borate (KTpClPB) and 2,5-thiophenylbis(5- tert-butyl-1,3-benzexazole) (TTBB), as a highly fluorescent chromoionophore, displays a calibration response for Ni 2+ ions over a wide concentration range of 1.0×10 −3 to 1.0×10 −8 M. It has a relatively fast response of <40 s. In addition to high stability and reproducibility, and relatively long working lifetime, the sensor possesses good selectivity for nickel ions over several common diverse ions. The fluorescence signal of the optode membrane can be easily recovered by immersion in EDTA solution. The optode was applied successfully to the determination of traces of Ni 2+ ion in edible oil and a wastewater sample from nickel electroplating industries.