DNA is less soluble in solutions containing isopropanol than in solutions containing ethanol. In contrast to precipitation with ethanol, which requires 2-3 volumes of alcohol, precipitation with isopropanol is performed with 0.6-0.7 volume of alcohol. Isopropanol is often the better choice when precipitating DNA from large volumes of solution. Precipitation with isopropanol, described here, is performed at room temperature to lessen the risk that solutes like sucrose or sodium chloride will be coprecipitated with the DNA.
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