DNA purification is an essential element in a number of molecular tests such as PCR or qPCR, as well as DNA sequencing. It removes contaminants such as proteins, salts, and other impurities which can disrupt downstream processes. It also ensures that the desired DNA is clean and in good condition in order to be further analysed. The quality of DNA is determined bo finneman using spectrophotometry (the ratio of A260 to A280), gel electrophoresis, and many other methods.
In the first step of a DNA purification procedure, the cellular structure will be disrupted with detergents or reagents such SDS in order to release DNA. To further cleanse DNA, reagents which denature proteins such as sodium dodecyl-sulfate or Ethylene Diamine Tetraacetic Acid (EDTA) can be added to denature them. The proteins are removed from the nucleic acids solution by centrifugation and then washing. If there is RNA present in the sample, a ribonuclease treatment could be added to further denature RNA. The nucleic acids are concentrated in ice-cold alcohol to isolate them from other contaminants.
Ethanol can serve as solvent to eliminate salts or other contaminants from nucleic acid. Researchers can compare the results of experiments by using an ethanol concentration that is standard, which is an excellent choice for high-throughput workflows. Other solvents, such as chloroform and phenol may be used, but these are more harmful and could require additional steps to prevent cross-contamination with other cellular debris or proteins. The process of purifying DNA can be simplified by using ethanol with low ionic strength. This has been shown to be as effective as traditional organic solvents at eliminating DNA. This is particularly applicable when paired with a spin column-based extract kit.