Anodic stripping voltammetry

Anodic Stripping Voltammetry (ASV) is an electroanalytical method used extensively in the detection and quantification of trace metals in various environmental, biological, and industrial samples. This technique combines the pre-concentration of the analyte at the electrode surface with its subsequent detection by voltammetry, making it highly sensitive and selective.

Principle

The ASV method involves three main steps: deposition, equilibration, and stripping. During the deposition phase, the analyte is pre-concentrated onto the electrode surface by applying a negative potential, which reduces the metal ions and deposits them as a thin layer of metal. This is followed by an equilibration period, where the potential is held constant to allow the system to stabilize. Finally, in the stripping phase, the potential is scanned in the positive direction, and the deposited metals are oxidized back into the solution. The current generated during the stripping phase is measured, which is proportional to the concentration of the analyte.

Instrumentation

The basic components of an ASV system include a potentiostat, a three-electrode system comprising a working electrode (often made of mercury or bismuth), a reference electrode, and a counter electrode. The choice of the working electrode material is crucial for the sensitivity and selectivity of the method.

Applications

ASV is widely used in environmental monitoring for the detection of trace metals like lead, cadmium, zinc, and copper in water bodies. It is also applied in the food industry for the analysis of heavy metals in food products, in clinical laboratories for the determination of metal ions in biological fluids, and in industrial processes for the monitoring of wastewater.

Advantages and Limitations

The main advantages of ASV include its high sensitivity, low detection limits, and the ability to analyze multiple metals simultaneously. However, the technique has limitations, such as the potential interference from other substances present in the sample, the need for careful surface preparation of the electrode, and the toxicity of some electrode materials like mercury.

See Also

• Voltammetry
• Electrochemistry
• Trace metal analysis