Electrophoresis technique is a method of separation in clinical laboratories to separate charged molecules from each other and into their constituents’ components. This happen in the presence of electric field. The electric field device is a typical ion exchanger, You can use it to separate many things such as proteins in body fluids for example urine, proteins in erythrocytes such as hemoglobin and Nucleic acids. Typically DNA and RNA just to mention a few.
In fact, many factors are responsible for the output of this procedure and are inherent, external and environmental. Inherent factors include magnitude of charge, charge density, molecular weight, and shapes of the material under investigation. Likewise, external and environmental factors include pH, electric field, viscosity of the solution, and temperature.
However, this process employs the use of electricity to separate charges in the presence of electric fields. The main electrical parameters used in electrophoresis are Voltage and Current or Power. High voltage is responsible to provide the electric field. However, when current pass through a substance with resistance and in this case the buffer, it evolves heat. Therefore, it is important to choose carefully combination of parameters to use for a particular procedure.
A typical instrument comprises of an electrophoresis tank and an electrophoresis power supply. The power supply is usually high voltage source to create the presence of electric field within the solution. The tank is a plastic material with two electrodes of tungsten or constantan. One electrode connects to the negative terminal of the power supply. The other electrode connects to the positive terminal of the high tension power supply. Moreover, the tank serves as container for the buffer and gel.
In electrophoresis, you hold one electrical parameter, current, voltage or power constant, but ideally you keep voltage constant. That is, keeping the voltage steady. But why is this so?
- Under constant current conditions (velocity of moving charge is directly proportional to current). With constant current, the velocity of the molecules is maintained but generates heat.
- With constant voltage conditions, the velocity of moving ions slows, but it does not generate heat during the course of the run
- At constant power conditions, the velocity slows but heating is kept constant