Biological samples are typically a mixture of molecules, viruses, bacteria, cells, and other particles. Considerable information can be acquired from a biological sample. However, before analysis, these samples are usually required to be separate in different components. For example, sample separation is an important step required in techniques such as PCR, gel-electrophoresis, DNA sequencing, etc. Accordingly, proper sample preparation is an important technique in the biomedical and research field. One of the techniques used for sample preparation is electrophoresis. During electrophoresis, the sample components are separated by applying  an electric field. One of the challenges associated with electrophoresis is the redox electrochemistry reactions that can result in corrosion and oxidation of the electrode and changes in pH. The following technology describes a method for controlling the pH changes in the flow channel.