Investigation of a fibre optic copper sensor based on immobilised α-benzoinoxime (cupron)

α-Benzoinoxime, a highly selective reagent used for the gravimetric and colorimetric determination of copper, was successfully immobilised on XAD-2 and coupled with optical fibres to investigate a sensor-based approach for determining copper. Reflectance measurements were used to quantify sensor response. Optimum response was obtained at a wavelength of 560 nm and at a solution pH of 7. Using a kinetic approach in which the rate of change of reflectance is measured over a 4-min period, the response was found to be linear in the range 5–127 ppm. After measurement, the sensor can be regenerated for reuse by immersing the probe in 0.1 M HCl. With continuous use, the sensing layer was found to be stable for at least 3 days. The advantages of using α-benzoinoxime in this way are compared with its use in the traditional gravimetric and colorimetric way.