Question

If your "low salt" sample has 1.9 mg/ml protein, how many microliters (υl) would you need in order to have exactly 30 micrograms of protein? [hint: first express everything in micrograms and microliters)

(give you answer to the nearest 0.1 ul)

Answer 1

To find out how many microliters (µl) of the sample you need to obtain exactly 30 micrograms (µg) of protein, you can use the following formula:

\[
\text{Concentration} = \frac{\text{Amount of substance}}{\text{Volume}}
\]

Given:
- Concentration of protein = 1.9 mg/ml
- Desired amount of protein = 30 µg

First, convert the concentration from mg/ml to µg/µl:

\[
1.9 \, \text{mg/ml} = 1.9 \, \text{µg/µl} \text{ (since 1 mg = 1000 µg and 1 ml = 1000 µl)}
\]

Now, we set up the equation to find the volume (V) needed:

\[
30 \, \text{µg} = 1.9 \, \text{µg/µl} \times V \, \text{(µl)}
\]

Now solve for \(V\):

\[
V = \frac{30 \, \text{µg}}{1.9 \, \text{µg/µl}} \approx 15.7895 \, \text{µl}
\]

Rounding to the nearest 0.1 µl:

\[
V \approx 15.8 \, \text{µl}
\]

Thus, you would need approximately **15.8 µl** of the "low salt" sample to obtain exactly 30 micrograms of protein.