Agarose gel electrophoresis is a fundamental technique in molecular biology used to separate, identify, and purify DNA or RNA fragments based on their size.
DNA fragments migrate toward the positive anode based on size
Source: Rungnaree Jaitham / Getty Images
Buffer and Gel Concentration Selection
0.7%–1.0% Agarose Gel: Best for separating large DNA fragments (2 kb – 10 kb).
1.2%–1.5% Agarose Gel: Ideal for medium-sized DNA fragments (0.2 kb – 3 kb).
2.0% Agarose Gel: Recommended for small DNA fragments or PCR products (50 bp – 500 bp).
Running Buffer: Use 1x TAE for large fragments (>12 kb) or 1x TBE for small fragments (<1 kb) with higher resolution.
Prepare the Agarose Gel
Take 2% agarose gel for example:
2g agarose powder
100ml buffer solution
Weigh the appropriate amount of agarose powder and add 1x TAE or TBE buffer. Microwave in short intervals until the agarose is completely dissolved and clear. Allow the solution to cool to approximately 50–60°C.
Cast the Gel and Insert the Comb
Avoid creating air bubbles near comb teeth. Cast the Gel and Insert the Comb：Avoid creating air bubbles near comb teeth. Add nucleic acid stain (e.g. Ethidium Bromide or safe nucleic acid dyes) if performing pre-casting. Pour the mixture into the gel casting tray and insert the comb. Allow it to solidify completely at room temperature for 20–30 minutes.
Set Up the Electrophoresis Tank
Place the solidified gel into the horizontal electrophoresis tank. Fill the tank with 1x running buffer (same buffer as in the gel) until the gel is fully submerged. Carefully remove the comb straight up to keep the wells intact.
Load DNA Samples and Ladder
Mix your DNA samples with 6x loading dye. Pipette the DNA ladder into the first well, then carefully load the prepared samples into subsequent wells.
Run the Gel
Connect the power leads (Black to negative/cathode, Red to positive/anode). Run the gel at 5–10 V/cm (distance between electrodes). Once the dye front reaches 70–80% of the gel length, turn off the power and visualize bands under a UV Transilluminator or Blue Light UV Transilluminator.
Horizontal Gel Operation
Beijing Liuyi Biotechnology Co., Ltd. (Liuyi Biotechnology) has over 50 years of expertise in manufacturing electrophoresis instruments. With a dedicated technical team and R&D center, we provide reliable and comprehensive production, from design to inspection and warehousing. We offer a full range of products, including:
- Electrophoresis Cells (Tanks/Chambers)
- Electrophoresis Power Supplies
- Blue LED Transilluminators
- UV Transilluminators
- Gel Imaging & Analysis Systems
In addition, we supply other laboratory instruments such as PCR machines, vortex mixers, and centrifuges.
If you are considering purchasing our products, please don’t hesitate to reach out. You can contact us via email at sales@ly.com.cn or info@ly.com.cn. Alternatively, feel free to call us at +86 15810650221, add us on WhatsApp at +86 15810650221, or connect with us on WeChat at 15810650221.
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Post time: Sep-09-2026
