Ultra trace mercury(II) detection by a highly selective new optical sensor

This paper presents the development and construction of a sensitive new optical sensor that is highly selective to Hg2+ ion in aqueous solution. The sensing element, the newly synthesized (1Z,2Z)-N′1,N′2-dihydroxy-N1,N2-dipyridin-2-ylethanediimidamide, incorporated into a plasticized poly(vinyl chloride) membrane, is capable of determining mercury(II) with a high selectivity over a wide dynamic range from 5.78 × 10−9 to 1.05 × 10−3 M at pH 4.0 with a lower detection limit of 1.71 × 10−9 M. The optode membraneʹs response to Hg2+ is fully reversible and reveals a very good selectivity towards Hg2+ ion over a wide variety of other metal ions in solution. Performance characteristics of the sensor evaluated as good reversibility, wide dynamic range, long life span, long-term response stability, and high reproducibility. The proposed optical sensor gives good results for applications in direct determination of mercury(II) in environmental real samples that are satisfactorily comparable with corresponding data from cold-vapor atomic absorption spectrometry.