2. Single-stranded dna (ssdna) concentration expressed in µg/ml
To determine the concentration of single-stranded DNA (ssDNA) as a µg/ mL
amount, the following conversion factor is used:
1 OD of ssDNA = 33 µg/mL
2
3. Single-stranded DNA isolated from M13mp18, a derivative of bacteriophage M13 used in
cloning and DNA sequencing applications, is diluted 10 µL into a total volume of 1000 µL
water. The absorbance of this diluted sample is read at 260 nm and an A260 value of 0.125 is
obtained. What is its concentration in µg/mL?
1 OD = 33 µg/mL
0.125 OD = x µg/mL ?
x µg/mL = 0.125 OD X 33 µg/mL
= 4.125 µg/mL
Therefore, the concentration of the diluted sample is 4.125 µg/mL
3
4. To determine the concentration of the M13mp18 DNA stock solution, this value must be
multiplied by the dilution factor:
4.125 µg/mL X 1000µl/10µl = 4125 µg/mL /10
= 412.5 µg/mL
Therefore, the stock of M13mp18 DNA has a concentration of 412.5 µg/mL.
4
5. Reference
Calculations for molecular biology and Biotechnology – A Guide to
mathematics in the laboratory, Second Edition – Frank. H. Stephenson
sivasan91@gmail.com
5
