DNA purification is an essential step in many molecular tests, including PCR and qPCR. It eliminates contaminants like salts, proteins and other impurities that can disrupt downstream processes. It also ensures the desired DNA is clean and is present so that it can then be used for further analysis. The quality of DNA can be assessed by using spectrophotometry or gel electrophoresis, and other methods.

The first step in the process of DNA purification is cell lysis. In this process, the cellular structure is disturbed with detergents or reagents such as SDS to release DNA. To further purify the DNA, reagents that are protein denatured such as sodium dodecyl sulfate and Ethylene grade school science classes diamine tetraacetic acids (EDTA) are added to denature the proteins. They are then removed from the nucleic acids solution through centrifugation and wash steps. If RNA is detected in the sample, it can be further denatured by adding ribonuclease. The nucleic acid is then concentrated in ice-cold alcohol to separate them from other contaminants.

Ethanol can serve as solvents to eliminate salts or other contaminants from nucleic acid. Researchers can evaluate the results of different experiments using a standard ethanol concentration, which is a good choice for workflows with high-throughput. Other solvents, such as chloroform or phenol can be used, however, they are more hazardous and require additional steps to avoid cross-contamination. The purification of DNA is made easier by using ethanol with a low ionic strength. This has been shown to work as well as conventional organic solvents in cleaning DNA. This is especially the case when paired with spin column-based extract kits.