The electrodes used in the electrophoresis process can vary widely, depending on the type of electrophoresis being performed. For example, when carrying out gel electrophoresis, one can choose from several different types of electrode depending on their requirements. Agarose gel electrophoresis, for instance, requires a buffer-filled chamber and two distinct electrodes, a cathode and an anode. These electrodes are placed at opposite ends of the chamber, with the buffered solution entraining the sample molecules poured in somewhere in between the two electrodes.
Polyacrylamide gel electrophoresis, another type of gel electrophoresis, usually requires two different electrodes. A power supply is used to place a gradient within the chamber, allowing the sample molecules to migrate through the gel to the various molecular destinations. As with agarose gel electrophoresis, an anode and a cathode are often chosen for this type of electrophoresis, although it is possible to try other types of electrodes.
The type of electrode chosen for a particular type of electrophoresis often depends on the results one hopes to gain from the experiment. The shape and size of the electrodes has an effect on the electrical field that is produced, in turn affecting the results of the electrophoresis. In addition, special pairings of different electrodes can be utilized to produce desired shapes and sizes of electrical field. For example, if one wishes to create a larger electrical field, one might choose to use an Ag/AgCl bead-filled anode and a plain stainless steel cathode. This combination of electrodes, while potentially more difficult to construct, will produce an effective electrical field in the desired shape and size.
The material chosen for the electrodes can vary as well. Stainless steel, silver, and gold are common, as is graphite. It is generally advisable to choose an electrode material that can handle the current needed to generate the desired field while still being cost effective. Of course, the ease of constructing the electrode is also a factor; if building the electrode is a difficult task, the end result may not be worth the effort involved.
Before beginning any type of electrophoresis, one needs to make sure that the proper electrodes have been chosen. Selecting the wrong type or having an inferior electrode construction can lead to skewed results. Therefore, it is important to research the process ahead of time and choose the appropriate electrode material and setup based on the criteria of the process in order to ensure successful results.
