III. DNA and RNA Oligonucleotide Concentration:
•
Concentration = A/(
ε
b) * 10
6
pmole/µl
•
Concentration = A/(
ε
b) * MW * 10
3
µg/ml
where A = absorbance,
ε
= molar extinction coefficient in liter/mole/cm,
b = pathlength in cm and MW = molecular weight.
For cuvettes with a 10 mm (1 cm ) pathlength, these equations simplify to:
•
Concentration = A/
ε
* 10
6
pmole/µl = (µg/ml)* (1000)/MW
•
Concentration = A/
ε
* MW * 10
3
µg/ml = (pmol/µl) * (MW)/1000
IV. dsDNA, RNA, ssDNA concentration:
•
A
260
* Conversion Factor * Dilution Factor = µg/ml concentration
OR
•
(A
260
- A
320
) * Conversion Factor * Dilution Factor = µg/ml concentration
Default conversion factors are:
1.0 O.D. unit = 50 µg/ml dsDNA concentration
1.0 O.D. unit = 40 µg/ml RNA concentration
1.0 O.D. unit = 33 µg/ml ssDNA concentration
A
260
/A
280
ratios are 1.8 and 2.0 for pure DNA and RNA preparations, respectively.
V. Quantitating UV-proteins:
Protein (mg/ml) = 1.55 * (A
280
– A
320
) – 0.76 * (A
260
-A
320
)
Coefficients 1 and 2 (defaults 1.55 and 0.76, respectively) can be changed for different proteins.
VI. Cells/ml:
Cells/ml = A600 * Conversion Factor * dilution factor
Default conversion factor is 5 x 10
8
cells/ml
50
