I do isolation of RNA from liver rat using genezol triRNA purekit geneaid company when i measure conc of RNA by nanodrop this ratio appear what does it mean ?
Hi Duaa Adnan,
with the Nanodrop, the UV absorbance at different wavelengths is measured. The important absorbances are at 230, 260 and 280 nm. However, regarding the absorbance at 230 and 280 nm not the absolute values but rather the ratios with the absorbance at 260 nm is important.
- A260: absorbance of nucleotides (RNA)
- A260/A280: should be around 2.0; if lower there might be protein, phenol or other contamination
- A260/A230: should be around 2.0-2.2, but definitely >1.7; if lower there might be EDTA, carbohydrates, guanidium or other contamination
Note: low RNA concentrations lead to low A260/A230 → in that case only check A260/A280 ratio
To ensure significance, A260 readings should be greater than 0.15. An absorbance of 1 unit at 260 nm corresponds to 44 μg of RNA per ml (A260 = 1 → 44 μg/ml). This relation is valid only for measurements at a neutral pH.
To sum this up, the ratios you get from your Nanodrop measurements tell you some information about your RNA's purity. If these ratios are too low, you should consider another round of RNA purification as you cannot really trust any downstream analysis/application.
Best,
Selene
Selene Lickfett Thank you very much for your clarification this ratio appear but i dont know how to explain it
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