Alcohol, particularly ethanol, can reduce or remove DNA from surfaces, but its effectiveness depends on several factors. It doesn't completely destroy DNA, but rather inhibits its recovery.
How Alcohol Affects DNA Removal
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Reduced DNA Recovery: Studies show that alcohol-based hand sanitizers significantly reduce the amount of DNA recovered from surfaces, especially when combined with DNA-rich materials like saliva. 1 This doesn't mean the DNA is gone, but the remaining DNA may be too fragmented or diluted for detection using standard methods.
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Interference with DNA Extraction: The alcohol's presence can interfere with the DNA extraction process itself, making it more difficult to isolate and purify DNA from a sample. 1
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Effectiveness Varies with Concentration: Higher concentrations of alcohol (like 96% ethanol) are more effective at reducing amplifiable DNA than lower concentrations or water alone. Cleaning with water and then 96% ethanol reduced DNA by 100-200 times. [2, 3](https://www.sciencedirect.com/science/article/abs/pii/S187517681730269X, https://www.fsigeneticssup.com/article/S1875-1768(17)30269-X/pdf) Hypochlorite (bleach) is even more effective at completely removing traces of DNA. 2
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Use in DNA Extraction: Interestingly, cold isopropyl alcohol is often used in DNA extraction experiments to precipitate DNA out of solution, making it visible. This is because DNA is insoluble in alcohol. [4, 5, 6, 7, 8](https://learn.genetics.utah.edu/content/labs/extraction/howto/, https://www.genome.gov/about-genomics/teaching-tools/strawberry-dna-extraction, https://imb.uq.edu.au/strawberry-dna-extraction-activity, https://www.genome.gov/sites/default/files/media/files/2023-04/How_to_extract_DNA_from_a_strawberry_508.pdf, https://www.michigan.gov/explorelabscience/-/media/Project/Websites/explorelabscience/pdf/Atomic-Lab-Kids/StrawberryExtractionInstructions_.pdf?rev=9479b08e29fd4221aba928e8d98b82a3&hash=992452537C72D773F764FCF0E935528D) This highlights the complex relationship between alcohol and DNA.
Conclusion:
While alcohol can reduce the amount of recoverable DNA from a surface, it is not a guaranteed method for complete DNA removal. The effectiveness depends on the type of alcohol, its concentration, and the nature of the DNA sample. Other methods, such as using bleach, are much more effective for complete DNA elimination.
