A turn-on fluorescence-based fibre optic sensor for the detection of cadmium

Downloading of the abstract is permitted for personal use only. A stable, compact and portable optical fibre sensor for the real time detection of cadmium ions in dilute aqueous media has been designed, developed and evaluated. The sensing mechanism was based on fluorescence turn-on of a coumarin (acting as the fluorophore) bearing a dipicolylamine moiety (acting as the metal ion receptor) in the presence of metal ions via photoinduced electron transfer (PET). The fluorophore was covalently immobilized onto the fibre surface by polymerisation and exhibited a significant increase in fluorescence intensity in response to Cd2+ in the μM concentration range. A referencing scheme allowing for corrections due to fluctuations of the excitation light and transmission properties of the optical fibre or environmental perturbation to the sensor system has been introduced using a highly stable perylene red based material as the internal reference. A high selectivity, excellent photo-stability and reversibility have also been demonstrated, making this type of sensor potentially well suited for in-situ monitoring of the metal in the environment