A novel non-extractive sequential injection procedure for determination of cadmium

This paper presents a novel non-extractive procedure for cadmium determination in a sequential injection (SI) system. The reaction is based on the formation of a complex by Cd(II), iodide ions, and 2-[2-(4-dimethylamino-phenyl)-vinyl]-1-ethyl-quinolinium iodide (R), commonly known as Quinaldine red. Complex-formation results in significant changes in the UV-Vis spectrum of R: the peak is significantly broadened and a shoulder appears near 618 nm. It is important to emphasize that no surfactant addition is needed for solubilization of the system. Under the optimum reaction conditions the calibration plot was linear in the range 1.12–11.24 mg L−1 Cd and the detection limit was 0.24 mg L−1 Cd. The method was tested for the analysis of mineral water and pharmaceutical samples spiked with cadmium.