17.5
ng/µL
1.84
2.19
17.5
ng/µL
1.84
2.19
The OD260 DNA Quantification tool calculates nucleic acid concentration from spectrophotometric readings and evaluates sample purity using the A260/A280 and A260/A230 ratios. This comprehensive analysis helps you determine both the quantity and quality of your DNA or RNA preparation in a single step. Purity assessment is critical before using samples in downstream applications such as PCR, cloning, sequencing, and transfection.
The tool performs two calculations:
1. Concentration:
C = A260 × Dilution Factor × Extinction Coefficient
2. Purity Ratios:
Inputs
Results
A260/A280 of 1.84 and A260/A230 of 2.19 indicate a clean dsDNA sample with a concentration of 17.5 ng/µL.
Inputs
Results
An A260/A280 of 1.32 suggests significant protein contamination, and A260/A230 of 0.91 indicates organic solvent or salt contamination. The sample should be re-purified.
A ratio below 1.7 for DNA or below 1.9 for RNA indicates protein contamination. Proteins absorb strongly at 280 nm due to aromatic amino acids (tryptophan, tyrosine, phenylalanine), which decreases the A260/A280 ratio. Phenol contamination can also lower this ratio. Consider additional purification steps such as phenol-chloroform extraction or column-based cleanup.
This pattern typically indicates contamination with organic compounds such as guanidinium thiocyanate (from RNA extraction kits), EDTA, carbohydrates, or residual phenol. These substances absorb at 230 nm. Try an additional ethanol precipitation or re-run the sample through a cleanup column.
Yes. NanoDrop spectrophotometers use the same Beer-Lambert principle with a micro-volume path length. Since NanoDrop automatically calculates concentration and ratios, this tool is useful for understanding the calculations or for standard cuvette-based spectrophotometers. Set the dilution factor to 1 if measuring undiluted on a NanoDrop.
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