Make a TAE Buffer in a Few Steps

The TAE Buffer Is Used to Study DNA Movement

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TAE buffer is a solution made up of Tris base, acetic acid and EDTA (Tris-acetate-EDTA). It 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 low ionic strength and low buffering capacity. It is best suited to electrophoresis of large (>20 kilobases) pieces of DNA and will need to be replaced frequently or recirculated for longer (>4 hours) gel run times. With that in mind, you may want to consider making several batches of the buffer.

Given that the buffer is easy to make and the steps can be carried out quickly, making more than one batch at a time shouldn't be particularly time-consuming or difficult. Using the instructions below, it should take just 30 minutes to make the TAE buffer.

What You Need for the TAE Buffer

Since making the TAE buffer only requires a quick and simple set of instructions, the number of materials needed for it isn't excessive. You'll just need EDTA (ethylenediaminetetraacetic acid) disodium salt, Tris base, and glacial acetic acid.

Making the buffer also requires a pH meter and calibration standards, as appropriate. You'll also need 600 milliliter and 1500 milliliters beakers or flasks as well as graduated cylinders. Finally, you'll need deionized water, stir bars, and stir plates.

In the following instructions, formula weight (each element's atomic mass is multiplied by the number of atoms, then the mass of each is added together) is abbreviated as FW.

Prepare a Stock Solution of EDTA

An EDTA solution is prepared ahead of time. EDTA will not go completely into a solution until the pH is adjusted to about 8.0. For a 500-milliliter stock solution of 0.5 M (molarity, or concentration) EDTA, weigh out 93.05 grams of EDTA disodium salt (FW = 372.2). Dissolve it in 400-milliliters deionized water and adjust the pH with sodium hydroxide (NaOH). Top up the solution to a final volume of 500 milliliters.

Create Your Stock Solution

Make a concentrated (50x) stock solution of TAE by weighing out 242 grams of Tris base (FW = 121.14) and dissolving it in approximately 750 milliliters of deionized water. Carefully add 57.1 milliliters of glacial acid and 100 milliliters of 0.5 M EDTA (pH 8.0).

After that, adjust the solution to a final volume of 1 liter. This stock solution can be stored at room temperature. The pH of this buffer is not adjusted and should be about 8.5.

Prepare a Working Solution of TAE Buffer

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 (millimolar) Tris-acetate and 1 mM EDTA. The buffer is now ready for use in running an agarose gel.

Wrapping Up

Check the inventory before you begin to make sure you have all of the above materials for the TAE buffer. Your supply personnel should be able to tell you if they have all the items you need in stock. You don't want to end up missing something in the middle of the procedure.