Selective and sensitive optical chemical sensor for the determination of Hg(II) ions based on tetrathia-12-crown-4 and chromoionophore I

A reversible optical membrane sensor for detection of Hg(II) was developed based on the colorimetric determination of tetrathia-12-crown-4-Hg(II), incorporating chromoionophore I (ETH5294) as a lipophilic H+-selective indicator, and sodium tetra phenyl borate (NaTPB) as a lipophilic anionic site. A decrease in absorption of the membrane at 664 nm and/or increase at 555 nm could be used as a suitable wavelength for quantitative determination of Hg(II). This membrane is capable of determining mercury(II) ions over a wide linear dynamic range 1.0 × 10−9 to 9.5 × 10−5 mol L−1 Hg(II) at pH 7.0 with detection limits of 8.1 × 10−10 mol L−1 Hg(II) and response time of 100 s. The optode reveals a very good selectivity toward Hg(II) ions over a wide variety of other metal ions in solution and the response to Hg(II) is fully reversible. Performance characteristics of the sensor evaluated as good reversibility, wide dynamic range, long life span, long-term response stability, and high reproducibility. The optode was applied to the determination of mercury(II) in water samples. The accuracy of the results was comparable to those obtained by cold vapor atomic absorption spectrometry.