Final answer:
The A260/A280 ratio is used to evaluate the purity of a DNA sample. Ratios between 1.8 and 2.0 are considered pure DNA samples.
Step-by-step explanation:
The A260/A280 ratio is calculated by dividing the absorbance at 260 nm by the absorbance at 280 nm. This ratio is used as an indicator of nucleic acid purity.
An A260/A280 ratio between 1.8 and 2.0 is generally considered to indicate pure DNA. Ratios below 1.8 suggest protein contamination, while ratios above 2.0 suggest RNA contamination.
For example, if the A260/A280 ratio of your DNA sample is 1.9, it indicates that your DNA sample is relatively pure.