Techniques of Paper Electrophoresis: Introduction, Procedure, Type, Advantages & Disadvantages

Introduction:

• Paper electrophoresis involves the use of a strip or sheet of filter paper as the stationary or supporting phase.

• This technique is commonly applied for the separation of small molecules like amino acids, peptides, and nucleotides.

Procedure:

illustration of paper electrophoresis

1. Preparation of the Paper:

• The filter paper strip is cut to the required size and soaked in a buffer solution to maintain a stable pH throughout the experiment.

2. Sample Application:

• A small aliquot of the sample is applied onto the paper, generally some distance away from one end.

• Precise application is crucial to prevent excessive spreading, which can degrade resolution.

3. Electrophoresis Chamber Setup:

• The paper strip is positioned in a chamber filled with a buffer solution. Both ends of the strip should be in contact with this buffer to ensure electrical conductivity.

• Electrodes (anode and cathode) are then placed at each end of the chamber.

4. Application of Electric Field:

• Upon connection to a power supply, an electric field is established across the paper strip.

• Charged molecules in the sample migrate toward the electrode of opposite charge.

5. Detection and Analysis:

• After electrophoresis, the paper strip is removed.

• The separated molecules can be detected using suitable staining or detection techniques, and their migration distance can be utilized for analysis.

Type of paper electrophoresis

• Paper electrophoresis can be classified based on the voltage applied during the process.

Here's a brief differentiation between high voltage and low voltage paper electrophoresis:

1. High Voltage Paper Electrophoresis:

1. Voltage: Uses higher voltages, typically above 2000V.

2. Duration: Faster separation due to the higher voltage, so the process is relatively shorter.

3. Resolution: Offers better resolution and sharper bands because of rapid movement.

4. Applications: Especially useful when rapid results are required or for separating smaller molecules.
   

2. Low Voltage Paper Electrophoresis:

1. Voltage: Uses lower voltages, typically below 300V.

2. Duration: Takes a longer time for separation due to the lower voltage.

3. Resolution: Bands may not be as sharp as in high voltage electrophoresis, but the process is gentler.

4. Applications: Suitable for separating larger molecules or when samples are sensitive to higher voltage conditions.

Advantages of paper electrophoresis:

1. Simplicity:

• Straightforward setup and minimal equipment required.

2. Low Cost:

• Filter paper and buffers are relatively inexpensive.

3. Educational Value:

• Great for teaching the basic principles of electrophoresis due to its simplicity.
  

Disadvantages of paper electrophoresis:

1. Resolution:

• Lower resolution compared to gel and capillary electrophoresis.

2. Fragility:

• Wet paper can tear easily during handling.

3. Capacity:

• Limited amount of sample can be loaded.