An optical copper(II)-selective sensor based on a newly synthesized thioxanthone derivative, 1-hydroxy-3,4-dimethylthioxanthone

A sensor membrane based on 1-hydroxy-3,4-dimethyl-9H-thioxanthen-9-one has been developed for the determination of copper(II) ions that displays excellent performance. The sensing membrane is capable of determining copper(II) with an outstanding high selectivity over a dynamic range between 1.6 × 10−7 and 1.3 × 10−2 M with a limit of detection of 4.0 × 10−7 M (25.1 ppb). The sensor shows a fast response time (<1 min) and the membrane can be used for more than 6 months without observing any major deviation. The optode revealed very good selectivity with respect to many cations including alkali, alkaline earth, transition and heavy metal ions. The proposed sensor could be used at a neutral pH of 7.5. It was applied to determination of copper in black tea, and in water. The optode was also used in photometric titration of the copper(II) ion with EDTA.