Development of a novel fluorimetric bulk optode membrane based on meso-tetrakis(2-hydroxynaphthyl) porphyrin (MTHNP) for highly sensitive and selective monitoring of trace amounts of Hg2+ ions

The fluorescence spectra and response characteristics of two porphyrin compounds meso-tetrakis(2-hydroxynaphthyl) porphyrin and meso-tetra (2-thiophene) porphyrin (MTHNP) to Hg2+ were investigated. MTHNP showed preferable fluorescence response to Hg2+. Thereby, an efficient and selective fluorimetric optode membrane based on the fluorescence quenching of MTHNP for Hg2+ ion determination at low concentration levels has been developed. The sensing membrane containing MTHNP reversibly responded to Hg2+ with a working concentration range covering from 5.0 x 10(-9) to 1.25 x 10(-5) M with a relatively fast response time less than 3 min. In addition to high stability, reversibility and reproducibility, the sensor showed extremely high selectivity toward Hg2+ ion with respect to some alkali, alkaline earth and heavy metal ions. The limit of detection for Hg2+ was 5.0 x 10(-9) M. The proposed fluorescent sensor was successfully applied to the direct determination of mercury content of biofenac eye drop, hair and different water samples. (C) 2014 Elsevier B.V. All rights reserved.