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OD260 Concentration Calculator

Calculate nucleic acid concentration from OD260 measurements

Configure Parameters
Select nucleic acid type and enter OD260 value
Results
Enter parameters to see calculation results

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Enter your parameters to see calculation results

Calculation Formulas & Scientific Background
Beer-Lambert Law principles for OD260 concentration calculations

Beer-Lambert Law

A = ε × l × c

Where A = absorbance, ε = molar extinction coefficient, l = path length (typically 1 cm), c = concentration

The Beer-Lambert Law relates the reduction of light to the materials which it travels through. Nucleotides absorb maximum light at 260nm due to their heterocyclic ring structures, making OD260 an accurate readout for nucleic acid concentration.

Concentration Calculation Formulas

1. Single-stranded DNA (ssDNA)

Concentration [μg/mL] = OD260 × 33

The extinction coefficient for ssDNA is 33 μg/mL per OD260 unit

2. Double-stranded DNA (dsDNA)

Concentration [μg/mL] = OD260 × 50

The extinction coefficient for dsDNA is 50 μg/mL per OD260 unit

3. Single-stranded RNA (ssRNA)

Concentration [μg/mL] = OD260 × 40

The extinction coefficient for ssRNA is 40 μg/mL per OD260 unit

Important Considerations

  • pH, buffer type, and guanine content can affect OD260 readings
  • Contaminating proteins absorb at 280nm; a 260/280 ratio of ~1.8 indicates pure DNA
  • Contaminating salts and organic compounds absorb at 230nm
  • Always use appropriate blanks and ensure the spectrophotometer is properly calibrated
  • Path length should be 1 cm for standard calculations; adjust if using different cuvettes