A DNA sample shows OD260 0.041 at a 1:50 dilution. The diluted sample concentration is

A DNA sample shows OD260 0.041 at a 1:50 dilution. The diluted sample concentration is

• A. 2.05 μg/mL
• B. 0.041 μg/mL
• C. 20.5 μg/mL
• D. 102.5 μg/mL

Answer: (A)

Measuring DNA by absorbance at 260 nm uses the fact that for double‑stranded DNA, an A260 of 1 equals about 50 μg/mL. So the concentration in a sample is A260 × 50 μg/mL, provided the measurement is done in a standard 1 cm path-length cuvette. Here, after a 1:50 dilution, the diluted sample has A260 = 0.041. Multiply by 50 to convert to μg/mL: 0.041 × 50 = 2.05 μg/mL. So the diluted sample concentration is 2.05 μg/mL. If you needed the original concentration before dilution, you’d multiply by 50 again to get 102.5 μg/mL.

Measuring DNA by absorbance at 260 nm uses the fact that for double‑stranded DNA, an A260 of 1 equals about 50 μg/mL. So the concentration in a sample is A260 × 50 μg/mL, provided the measurement is done in a standard 1 cm path-length cuvette.

Here, after a 1:50 dilution, the diluted sample has A260 = 0.041. Multiply by 50 to convert to μg/mL: 0.041 × 50 = 2.05 μg/mL. So the diluted sample concentration is 2.05 μg/mL. If you needed the original concentration before dilution, you’d multiply by 50 again to get 102.5 μg/mL.