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 optical sensor responded to Hg2 + from 5.0 × 10− 9 to 1.25 × 10− 5 M with a relatively fast response time.•It showed excellent reproducibility, reversibility and selectivity.•The fluorescent sensor was successfully applied to the determination of mercury content of different real samples.

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 × 10− 9 to 1.25 × 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 × 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.

Graphical abstractQuenching of fluorescence emission of the mercury-selective optical sensor in the presence of varying concentrations of Hg2 + ion from 5.0 × 10− 9 to 1.25 × 10− 5 M. The inset: Fluorescence excitation and emission spectra of optode membrane, λex = 425 nm and λem = 655 nm.Figure optionsDownload full-size imageDownload as PowerPoint slide