A DNA sample yielded an OD260 of 0.041 at a 1:50 dilution from a 0.4 mL sample. What is the total amount of DNA in the 0.4 mL sample?

A DNA sample yielded an OD260 of 0.041 at a 1:50 dilution from a 0.4 mL sample. What is the total amount of DNA in the 0.4 mL sample?

• A. 41 μg
• B. 4.1 μg
• C. 410 μg
• D. 0.41 μg

Answer: (A)

A260 absorbance is used to estimate DNA concentration, with double-stranded DNA having 1 A260 corresponding to about 50 μg/mL. Here, the diluted sample shows an OD of 0.041 at a 1:50 dilution, so the concentration in the diluted solution is 0.041 × 50 μg/mL = 2.05 μg/mL. Since this was produced by diluting the original sample 50-fold, the original sample’s concentration is 2.05 μg/mL × 50 = 102.5 μg/mL. The total DNA in the 0.4 mL original sample is then 102.5 μg/mL × 0.4 mL = 41 μg.

A260 absorbance is used to estimate DNA concentration, with double-stranded DNA having 1 A260 corresponding to about 50 μg/mL. Here, the diluted sample shows an OD of 0.041 at a 1:50 dilution, so the concentration in the diluted solution is 0.041 × 50 μg/mL = 2.05 μg/mL. Since this was produced by diluting the original sample 50-fold, the original sample’s concentration is 2.05 μg/mL × 50 = 102.5 μg/mL. The total DNA in the 0.4 mL original sample is then 102.5 μg/mL × 0.4 mL = 41 μg.