Thermo Fisher Scientific
29
Thermo Scientific KingFisher Plant DNA Kit Instruction Manual
Protocols and Pipetting Instructions
Quantification and determination of the purity of DNA
It is recommended to measure the absorbance at 320 nm,
280 nm, and 260 nm. The concentration of DNA can
be defined with the absorbance at 260 nm (A260). One
unit at 260 nm corresponds to 50 µg of DNA per ml.
The ratio between the A260/A280 indicates the purity of
the DNA, and the value for DNA should be ≥ 1.7–2.0.
A Thermo Scientific NanoDrop can be used for the direct
measurement of DNA without diluting the sample.
It is recommended that A320 correction is used for the
absorbance values. Subtract the A320 from the A260 and
A280 ratios to remove the effects of carryover of the
magnetic beads.
Use these calculations to measure the DNA content:
• Concentration of DNA
=
50 µg/ml x (A260 – A320) x dilution factor
• Total amount of DNA
=
concentration x volume of sample in ml
• Purity of DNA
=
(A260 – A320)/(A280 – A320)
Quantification and
determination of
the purity of DNA
