On the Method of Ammonium Acetate in DNA Precipitation
If you want to study the technique of DNA precipitation, the use of 7.5M ammonium acetate (Ammonium Acetate) is the most important method. 7.5M, the concentration is moderate, and the DNA can be effectively precipitated during the process of DNA precipitation. The reason is that ammonium acetate can change the ionic strength of the solution, promote the interaction between DNA molecules, and then precipitate out of the solution.

To perform this precipitation method, follow strict steps. Prepare the solution containing DNA first, slowly add an appropriate amount of 7.5M ammonium acetate, and stir gently in between to fully mix the two. Then, put it in a suitable environment, or let it stand at low temperature, or apply moderate centrifugation force. In this way, DNA is gradually precipitated, and a pure DNA sample can be obtained.

In contrast, 75M ammonium acetate is used for DNA precipitation, and this concentration is very different from 7.5M. If the concentration of 75M is too high, although it can accelerate the precipitation of DNA, it is easy to cause impurities to sink together and affect the purity of DNA. Therefore, when using 75M ammonium acetate, it is necessary to carefully control the conditions or supplement other purification methods to ensure the purity of the obtained DNA.

Generally speaking, 7.5M ammonium acetate precipitates DNA because the operation is smooth and the resulting product has high purity; although 75M ammonium acetate precipitates rapidly, it is necessary to pay attention to the interference of impurities. Both have their advantages and disadvantages. Experimenters should make careful choices according to their specific needs to achieve the desired effect.