Determination of Cesium on Nickel Hexacyanoferrate‐Aluminum Oxide Modified Electrodes

This report investigates the electrochemical behavior of hexacyanoferrate casted on Ni‐Al₂O₃ modified electrodes and the preconcentration and detection of cesium ions on such films. It also studies the morphology and the composition of these surfaces. The film was grown on a glassy carbon (GC) surface. Five consecutive voltammetric cycles applied within 0.0 V and ?1.6 V at a scan rate of 10 mV/s were enough to cast the film. Scanning electron microscopy (SEM) analyses showed a homogeneous, porous but broken surface of the film. Its composition was studied by X‐ray diffraction (XRD). The presence of NiHCFe was confirmed by Fourier transformed infrared spectroscopy (FT‐IR). The Cs⁺ preconcentration from diluted solutions was accomplished in 90 s, under a negative potential of ?0.20 V applied to the modified working electrode. The detection of cesium has a good sensitivity and a wide linear interval (10^?8 and 10^?12 mol L^?1). Even so, the limit of detection calculated was extremely low (2×10^?16 mol L^?1), cesium concentrations lower than 10^?12 mol L^?1 gave signals with no analytical significance. However, to our knowledge, this is the lowest level of cesium ever detected by an electroanalytical technique.