The absolute A260 and A280 values and their ratio provide what essential information for a DNA sample?

The absolute A260 and A280 values, along with their ratio, provide crucial insights into the quality and purity of a nucleic acid sample, specifically indicating concentration and the presence of RNA or protein contamination.

The A260 measurement is used to determine the concentration of nucleic acids (DNA or RNA) in a solution, as nucleic acids absorb UV light at 260 nm. A higher A260 indicates a higher concentration of nucleic acids. The A280 value, on the other hand, is used to assess the level of protein contamination, as proteins typically absorb UV light at 280 nm.

The ratio of A260 to A280 is particularly significant. A ratio of approximately 1.8 is generally considered indicative of pure DNA, whereas a lower ratio might suggest the presence of proteins or other contaminants. Thus, the A260 and A280 values, along with their ratio, are essential in evaluating the concentration of the DNA and assessing the level of RNA or protein contamination present in the sample.