Characterization of an azo-calix[4]arene-based optical sensor for Europium (III) ions

Selective and sensitive optical sensor membranes (optodes) were elaborated to detect cations in aqueous solutions. The sensing films are based on chromogenic calix[4]arene derivatives. The optode membranes were studied using UV/Vis absorption spectroscopy measurements. The sensitivity of the optode has been tested for Pb2 +, Cd2 +, Mg2 + and Eu3 + ions at pH 6.8. The results showed a good selectivity response towards Eu3 +. Low selectivity coefficients were observed for Cd2 + and Mg2 + where Pb2 + can be considered as interfering ions. The characteristics of this optode such as response time, regeneration, reproducibility and lifetime are discussed.