1. What is the NEB Concentration Equation?

The NEB (Nucleic Acid Extraction Buffer) concentration equation calculates the molar concentration of a nucleic acid solution from its optical density and extinction coefficient. This is a fundamental calculation in molecular biology for quantifying DNA or RNA samples.

2. How Does the Calculator Work?

The calculator uses the NEB concentration equation:

Where:

• \( od \) — Optical density (absorbance units)
• \( ext \) — Extinction coefficient (L/mol/cm)
• \( conc \) — Concentration (mol/L)

Explanation: The equation is based on Beer-Lambert law which states that absorbance is directly proportional to concentration.

3. Importance of Concentration Calculation

Details: Accurate concentration measurement is essential for downstream applications like PCR, sequencing, and cloning where precise amounts of nucleic acids are required.

4. Using the Calculator

Tips: Enter optical density (typically measured at 260nm for nucleic acids) and the appropriate extinction coefficient. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical extinction coefficient for DNA?
A: For double-stranded DNA, it's approximately 0.020 L/μg/cm (or 6600 L/mol/cm when using molar units).

Q2: What wavelength should I use for measurement?
A: Nucleic acids are typically measured at 260nm, while proteins are measured at 280nm.

Q3: How do I prepare samples for measurement?
A: Use a blank with the same buffer as your sample. For accurate results, the OD should be between 0.1 and 1.0.

Q4: What affects the accuracy of this calculation?
A: Sample purity, proper blanking, and using the correct extinction coefficient for your specific nucleic acid.

Q5: Can I use this for RNA concentration?
A: Yes, but use the appropriate extinction coefficient for RNA (typically 0.025 L/μg/cm or 7700 L/mol/cm).