An Optode Sensor for Cu²⁺ with High Selectivity Based on Porphyrin Derivative Appended with Bipyridine

Abstract

A porphyrin derivative (fluorophore) appended with bipyridine (ionophore) has been applied for preparation of a Cu²⁺-sensitive optical chemical sensor, which is based on fluorescence quenching of porphyrin derivative entrapped in a poly(vinyl chloride) membrane by the energy transfer process. The sensor exhibits a linear response toward Cu²⁺ in the concentration range 2.0 × 10^-8 - 1.0 × 10^-5 M, with a working pH range from 6.0 to 8.0 and a high selectivity. The detection limit is 5 × 10^-9 M. The response time for Cu²⁺ is less than 5 min with concentrations lower than 5 × 10^-6 M. The optode can be regenerated using 0.3 M EDTA (pH 9) and acetate buffer solution. The effect of the composition of the sensor membrane was studied, and the experimental conditions were optimized. The sensor has been used for direct determination of Cu²⁺ in water samples with satisfied results.