260/280 ratio

The “260/280 ratio” is a commonly used metric in molecular biology to assess the purity of nucleic acid samples, such as DNA and RNA. This ratio compares the absorbance readings at 260 nm and 280 nm wavelengths, measured using a spectrophotometer. A ratio of ~1.8 is generally accepted as pure for DNA, while a ratio of ~2.0 is typical for pure RNA. Deviations from these values may indicate contamination by proteins, phenol, or other substances, which can affect downstream applications. Understanding and monitoring the 260/280 ratio is essential for researchers to ensure sample quality and reliability in experiments like PCR, sequencing, and gene expression analysis.