Abstract

A new optical sensor for highly sensitive and selective determination of ultra-trace amounts of mercury(II) ions is developed. This optode is based on the interaction of 1,15-diaza-3,4,12,13-dibenzo-8-oxa-16,18-pyridin-5,1-dithiacyclo octadecane-2,14-dione with Hg(II) in plasticized (2-nitrophenyloctyl ether (o-NPOE)) polyvinyl chloride (PVC) membrane incorporating chromoionophore V as a lipophilic H⁺-selective indicator. By increasing Hg(II) concentration, the absorbance of chromoionophore V in the membrane decreased at 668 nm whereas the absorbance at 567 nm increased. With the proposed sensor at pH 6.3, mercury(II) can be measured in the range of 1.0 × 10⁻¹²–8.6 × 10⁻⁴ mol L⁻¹ with a limit of detection 5.3 × 10⁻¹³ mol L⁻¹. The relative standard deviation for eight determination of 1.0 × 10⁻¹⁰ mol L⁻¹ Hg(II) was 2.8%. The results obtained for the determination of mercury ions in water samples, SRM, and tomato leaves using the proposed optode were found to be comparable with the well-established cold vapor atomic absorption spectrometry.