Anodic Stripping Voltammetry
Anodic Stripping Voltammetry is a method to demonstrate the presence of multiple metals in water. This method is usually applied to investigate the water quality of sewage, surface or drinking water.
For Anodic Stripping Voltammetry several steps need to be performed during which, low, medium and high potential are applied to an electrode in a certain volume of water.
First a high potential is applied, to clean the electrode. The samples (water) is stirred for a certain period (usually between 60 and 300 seconds) at a low potential. With this low potential, all dissolved metal ions (charged atoms) in the water are reduced and remain on the electrode as metal film.
After stirring, the electrode is covered with metal particles. Their amounts are measured with a potentiostat. The potentiostat linearly increases the potential. At each redox potential of a metal, this metal oxidizes on the electrode flap. Each time one of the metals is oxidized an electrical current flows and is read by the potentiostat (Figure 1).
When the values found are displayed in a graph, this graph will show various peaks (see below). These buds each stand for the redox potential associated with a certain kind of metal.
Advantages of Anodic Stripping Voltammetry
Anodic Stripping Voltammetry allows researchers to detect multiple types of metal in one trial. Researching water quality using Anodic Stripping Voltammetry is also fast and accurate.
An anodic Stripping Voltammetry test is very easy to perform on location (outside) by taking a sample of the water, testing it with the potentiostat linked to a laptop or tablet.
(photo test fixture)
The metal film formed during the reduction step concentrates the metal particles at the electrode, thus the detection of very low concentrations (ppb range) of metal ions is possible.
Applications of Anodic Stripping Voltammetry
Anodic Stripping Voltammetry is widely used for testing drinking water quality (water coming out of the tap) and sewage or waste water – water that leaves the treatment plant before being discharged into surface water.
However, there are also known applications in which the water quality of sewage water in the sewage pipes is continuously measured, using a clever underground test rig. When a pipe starts to rust, this is immediately noticed by means of the increased concentration of metals in the water. It is therefore possible to intervene in good time.
What do you need for Anodic Stripping Voltammetry?
To perform a water quality test you only need a potentiostat, such as the EmStat Blue with a sensor sensitive to metals. When you connect the potentiostat to the device (for example, your laptop) and use the included user-friendly software, you can directly measure and analyze results.