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^{thorn} 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 (10⁸ and 10 ¹² mol L ¹). Even so, the limit of detection calculated was extremely low (2 10¹⁶ 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.