1. What is RNA Concentration?

RNA concentration is typically measured by absorbance at 260 nm (A260), where nucleic acids absorb UV light most strongly. The standard conversion factor is 40 μg/mL for 1 absorbance unit at 260 nm.

2. How Does the Calculator Work?

The calculator uses the RNA concentration formula:

Where:

• \( C \) — RNA concentration (μg/mL)
• \( A_{260} \) — Absorbance at 260 nm
• 40 — Conversion factor (μg/mL per absorbance unit)

Explanation: Pure RNA has an extinction coefficient of 40 μg/mL for each absorbance unit at 260 nm.

3. Importance of RNA Concentration

Details: Accurate RNA concentration measurement is crucial for downstream applications like RT-PCR, sequencing, and other molecular biology techniques.

4. Using the Calculator

Tips: Enter the A260 value from your spectrophotometer. The value should be between 0.001 and 1.0 for best accuracy (dilute samples if A260 > 1.0).

5. Frequently Asked Questions (FAQ)

Q1: Why is 40 used as the conversion factor?
A: This is the standard extinction coefficient for RNA, meaning 40 μg/mL of RNA gives an A260 of 1.0 in a 1 cm pathlength cuvette.

Q2: What if my A260 is above 1.0?
A: Samples with A260 > 1.0 should be diluted as absorbance readings become less accurate at higher values. Dilute and remeasure.

Q3: How does this differ from DNA concentration?
A: DNA uses a conversion factor of 50 μg/mL per A260 unit, while RNA uses 40 μg/mL.

Q4: What affects the accuracy of this measurement?
A: Contaminants like proteins or phenol can affect A260 readings. The A260/A280 ratio should be ~2.0 for pure RNA.

Q5: Can I use this for RNA in TE buffer?
A: Yes, but note that TE buffer itself has some absorbance at 260 nm, so blank with TE buffer.