What’s in Your Tube?: A Quick Guide to Measuring DNA by Spectrophotometry
Type
Blog Post
Published
July 1, 2025, 1:15 p.m.
... easy to measure sample concentration and purity using only a tiny bit of the sample itself — so easy ...instrument can calculate a sample’s nucleic acid concentration based on the sample’s absorption at 260 nm (...spectra of a mixed sample.
But, other molecules that may be present in the sample also absorb light...levels exceed 70% of the sample content (Loughrey and Matlock, 2016). So, even samples with “good” A260/280...nm, you may have phenol in your sample.
RNA contaminants
DNA samples can also be contaminated with RNA.... To confirm RNA in your DNA sample, you will need to use a complementary assay, such as a fluorescence...especially problematic in low-concentration samples (samples with concentrations < 10 ng/μL), where absorbance...