260/280 ratio protocol for nucleic acid analysis

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R Bishop
R Bishop's picture
260/280 ratio protocol for nucleic acid analysis

Just in case (like me) you forgot what a "good" 260/280 ratio is for your purified nucleic acid here's a simple rule of thumb.
Compute the absorbance ratio 260 nm to 280 nm. We use a Nanodrop, but any spectrophotometer will do.
Pure DNA (without protein or RNA) will have a 260:280 absorbance ratio of 1.85.
Pure RNA will have a 260:280 ratio of 2.0.