Think a “perfect” A₂₆₀/A₂₈₀ means perfect DNA?

Not so fast!
That ratio is a quick screen—not a verdict. Under neutral conditions, dsDNA sits around ~1.8 while RNA is closer to ~2.0. So when a “DNA” sample reads >2.0, the most common culprit isn’t super-purity—it’s RNA carryover, which pushes absorbance up at 260 nm more than at 280 nm. Protein contamination would actually pull the ratio down, and phenol/salts usually show up as a low A₂₆₀/A₂₃₀ and shoulders in the spectrum. Ultra-dilute samples can even inflate the ratio due to baseline noise and blanking errors.

💡 See why >2.0 isn’t always “better”