Synthesis and use of novel rhodanine derivatives to fabricate potentiometric sensors for the determination of toxic heavy metal ions

The detection of heavy metals in water samples is of high critical importance due to associated ecological and public health risks posed by heavy metals. In this study, we synthesized novel rhodanine derivative molecules (4a-4b and 5a-5b) and studied their potential uses as ionophores in the design of ion selective potentiometric sensors. Based on these rhodanine derivative molecules, we developed ion selective sensors sensitive for two different toxic heavy metal ions, cadmium(II) and copper(II). We investigated the potentiometric performance of these sensors in detail with respect to many sensor parameters such as linear concentration range and limit of detection, and also compared the analysis data obtained from these sensors with those from atomic absorption spectroscopy (AAS), and sensors from previous reports. Among multiple sensors developed in the present study, optimum two sensors (12 and 40) were found to have linear concentration ranges of 1.0 x 10-1-1.0 x 10-5 and 1.0 x 10-1-1.0 x 10-6 M; and limits of detection of 2.56 x 10-6 and 7.24 x 10-7 M for copper(II) and cadmium (II) ions, respectively. They were also shown to work ideally in the pH range of 4.0-10.0, and with a response time of less than 5s. Besides, the surfaces of these new sensors were characterized using scanning electron microscopy (SEM). We also successfully applied these sensors in the analysis of cadmium and copper ions in different water samples including environmental water samples.