You need to know the desired A260/A280 ratio and the concentration of RNA in order to determine the amount of RNA required for cDNA synthesis based on the A260/A280 ratio. The RNA content in this instance is 991 ng/l, while the A260/A280 ratio is reported as 2.07.
The ratio of A260 to A280 is frequently used to determine the purity of RNA. The A260/A280 ratio for pure RNA should ideally be around 2.0. Nevertheless, depending on the sample and purification technique, fluctuations in this ratio may occur.
You can use the following formula to determine how much RNA is required:
Volume (in l) x Concentration of RNA (in ng/l) = Amount of RNA (in g).
Let's start by supposing you wish to create c DNA from a certain amount of RNA.
For example, suppose you want to use 10 l of RNA The amount of RNA (in g) is equal to 991 ng/l 10 l = 9910 ng.
The amount must now be changed from nanograms (ng) to micrograms (g), as the latter unit is more frequently applied in molecular biology applications: The amount of RNA (in g) is equal to 9910 ng 1000 = 9.91 g.
The A260/A280 ratio is 2.07, therefore if you wish to use 10 l of RNA for cDNA synthesis, you would require about 9.91 g of RNA.