Sonoelectroanalysis: Anodic Stripping Voltammetric Determination of Cadmium in Whole Human Blood

The quantitative detection of cadmium in human blood is shown to be possible by anodic stripping voltammetry under conditions of insonation. An immersion horn probe is introduced into a thermostatted conventional three‐electrode cell opposite a Nafion‐coated mercury plated glassy carbon electrode. The enhanced mass transport associated with power ultrasound yields efficient preconcentration of the cadmium before it is detected using anodic differential‐pulse stripping voltammetry. Insonation further offers the crucial benefits of first surface activation and cleaning, helping to prevent electrode fouling by the organic components in blood and second fully equilibrating “free” and “bound” Cd²⁺ ions in the complex matrix. Acoustic streaming and cavitation promote the mass transport of cadmium to the surface of electrode, facilitating measurements in solutions of low cadmium concentration, where “silent” measurements fail to yield an analytical signal. The system is calibrated using standard micro additions of cadmium to give the total amount of cadmium in blood. The calibration plot, showing the dependence of the cadmium stripping peak height on cadmium concentration in 1 : 50 diluted blood samples, was linear in the range 1×10^?10 M to 4×10^?9 M Cd²⁺. The values of cadmium concentration obtained using sonoelectroanalytical methodology were compared with the results obtained by independent atomic absorption spectroscopy (AAS) measurements and good agreement was found.