In the previous part, we explained how to go through the process of DNA extraction from blood by using the kit for extracting DNA from blood based on column method, which is an imported product from Taiwan’s Favorgen company. In this part, we are going to control the quality of DNA extraction process from blood.
After Blood DNA extraction kit process, you have to control the quality of the performed process.
Quantitative determination of the amount of extracted DNA is done using the DNA extraction kit from blood with the Nanodrop device. DNA samples with a ratio of 260/280 above 1.7 and a ratio of 260/230 with a value of 2.2 have acceptable purity in terms of DNA quality. Also, in order to determine the quality of DNA samples, these samples can be taken on a 1% agarose gel to check for qualified none smear DNA . (The existence of a smear indicates degraded DNA ).
How to calculate DNA extraction process quantitatively:
Quantity and quality of the DNA sample is checked by using Nanodrop . ( HORC-UB-W-30-00)
The concentration of DNA sample per 200 µl of whole blood is 5-50 µg, which depends on the type of sample and the number of cells. 260/280: 1.7-2.0 and 260/230: 1.7-2.2 are acceptable.
OD260 is the optical absorbance of the tested sample at a wavelength of 260 nm. The optical absorption of DNA is specifically investigated at this wavelength.
OD280: The optical absorbance of the tested sample at a wavelength of 280 nm. The optical absorption of protein is specifically investigated at this wavelength.
OD230: The optical absorbance of the tested sample at a wavelength of 230 nm. The optical absorption of RNA, EDTA, phenol, guanidine thiocyanate and carbohydrates are investigated at this wavelength.
DNA sample concentration above 10ng/µl, with a ratio of 260/280 value of 1.7-2.0 and a ratio of 260/230 value of 1.7-2.2 is acceptable.
DNA concentration lower than 10ng/µl and OD260/OD280 lower than 1.7 and OD260/OD230 lower than 1.7 are not suitable.
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