# Prbbbb:dna measurement on plate v1

(Difference between revisions)
 Revision as of 07:02, 20 May 2009 (view source) (→Calculation)← Previous diff Revision as of 10:23, 20 May 2009 (view source) (→Calculation)Next diff → Line 19: Line 19: * DNA extinction coefficient e: 50 [(ng * cm) / µl] * DNA extinction coefficient e: 50 [(ng * cm) / µl] - * path length: + * path length in mm / in cm: - d = V / (3.3^2 * mm^2) + d' = V / (3.3^2 * mm^2) - V... volume per well in µl + d  = d'/10 + **V... volume per well in µl '''formula''' '''formula''' Line 27: Line 28: c = (A * e) / d c = (A * e) / d - * c... DNA concentration in ng / µl + ** c... DNA concentration in ng / µl - * A... Absorbance @ 260 nm + ** A... Absorbance @ 260 nm - * d... path length in cm + ** d... path length in cm ==Procedure== ==Procedure==

## Materials

• (or any reader that accepts 384 plates and can measure at 260 and 280 nm)
• 384 well UV transmissive plate with flat clear bottom
• we use Greiner UV star Cat # 781 801
• miniprepped DNA, at least 30 µl

## Calculation

parameters

• well dimension: flat bottom 3.3 mm x 3.3 mm
• DNA extinction coefficient e: 50 [(ng * cm) / µl]
• path length in mm / in cm:
``` d' = V / (3.3^2 * mm^2)
d  = d'/10
```
• V... volume per well in µl

formula

``` c = (A * e) / d
```
• c... DNA concentration in ng / µl
• A... Absorbance @ 260 nm
• d... path length in cm

## Procedure

1. Pipette exact volume of DNA samples into 384 well plate
2. measure 260 nm and 280 nm absorbance on plate reader
3. Pipette sample back into storage plate
4. calculate DNA concentration from formula above (compare to reference)

## Notes

Please feel free to post comments, questions, or improvements to this protocol. Happy to have your input!

raik: This protocol is quick and robust in my hands.