Swati has extracted RNA from Rattus novergicus. She wants to quantify it for further downstream process. From prior experience, she knows that not more than 100 μg of RNA can be yielded from a fully grown rat. There is some problem in the quantification machine they are using and its absorbance reading is not showing beyond 0.5. She intends to dilute the RNA sample in 100 μl of distilled water. What is the ratio in which she should dilute the sample to get the absorbance range within 0.5?

To answer this question, we need to understand the relationship between absorbance, concentration, and path length, which is described by the Beer-Lambert Law: A = εlc, where A is absorbance, ε is the molar absorptivity, l is the path length, and c is the concentration.

In this case, we know that the maximum absorbance the machine can read is 0.5, and we want to find the dilution ratio that will bring a 100 μg RNA sample within this range.

First, we need to know the molar absorptivity of RNA, which is typically around 0.025 (μg/ml)^-1cm^-1 at 260 nm. The path length is usually 1 cm in most spectrophotometers.

So, we can rearrange the Beer-Lambert Law to solve for concentration: c = A / (εl).

Substituting the known values, we get: c = 0.5 / (0.025 * 1) = 20 μg/ml.

This means that in order to get an absorbance of 0.5, the concentration of the RNA sample needs to be 20 μg/ml.

If Swati has 100 μg of RNA, she would need to dilute it to a final volume of: 100 μg / 20 μg/ml = 5 ml.

Since she intends to dilute the RNA sample in 100 μl of distilled water, the dilution ratio would be: 5 ml / 100 μl = 50.

Therefore, Swati should dilute her RNA sample 1:50 in order to get the absorbance within the range of 0.5.