Saturday, May 9, 2009

How To Make TAE Buffer

Tris-acetate-EDTA (TAE) buffer is historically the most common buffer used for agarose gel electrophoresis in the analyses of DNA products resulting from PCR amplification, DNA purification protocols, or DNA cloning experiments. This buffer has a low ionic strength and low buffering capacity. It is best suited to electrophoresis of large (>20 kb) pieces of DNA and will need to be replaced frequently or recirculated for longer (>4 h) gel run times.

Time Required: 30 minutes

1. Prepare a Stock Solution of EDTA

An EDTA (ethylenediamine tetraacetic acid) solution is prepared ahead of time. EDTA will not go completely into solution until the pH is adjusted to about 8.0. For a 500 mL stock solution of 0.5 M EDTA, weigh out 93.05 g EDTA disodium salt (FW = 372.2). Dissolve in 400 mL deionized water and adjust the pH with NaOH. Top up the solution to a final volume of 500 mL.

2. Prepare a Stock Solution of TAE

Make a concentrated (50x) stock solution of TAE by weighing out 242 g Tris base (FW = 121.14) and dissolving in approximately 750 mL deionized water. Carefully add 57.1 ml glacial acid acid and 100 mL of 0.5 M EDTA (pH 8.0) and adjust the solution to a final volume of 1 L. This stock solution can be stored at room temperature. The pH of this buffer is not adjusted and should be about 8.5.

3. Prepare a Working Solution of TAE

The working solution of 1x TAE buffer is made by simply diluting the stock solution by 50x in deionized water. Final solute concentrations are 40 mM Tris acetate and 1 mM EDTA. The buffer is now ready for use in running an agarose gel.

What You Need:

• EDTA disodium salt
• Tris base
• Glacial acetic acid
• pH meter and calibration standards as appropriate
• 600 mL and 1500 mL beakers or flasks
• Graduated cylinders
• Deionized water
• Stir bars and stir plates


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