Optical sensor based on 1,3-di(2-methoxyphenyl)triazene for monitoring trace amounts of mercury(II) in water samples

A new optical sensor for highly sensitive and selective determination of mercury(II) ion in aqueous solutions is developed. The mercury sensing membrane was prepared by incorporating 1,3-di(2-methoxyphenyl)triazene (MPT) as chromoionophore in the plasticized PVC membrane containing tris(2-ethylhexyl)phosphate (TEHP) as plasticizer. The proposed sensor displays a wide linear range of 9.0 × 10−10–2.5 × 10−7 M with a low detection limit of 2.0 × 10−10 M in aqueous solutions at pH 4.0. This sensor has a relatively fast response time of less than 5 min. In addition to high stability and reproducibility, it shows a unique selectivity towards Hg2+ ion with respect to common coexisting cations. The sensor can readily be regenerated by exposure to a solution of sodium iodide (0.01 M). The proposed optode was applied to the determination of Hg2+ in water samples.