You were given an unknown protein solution. After 100 times dilution the absorba

Question

You were given an unknown protein solution. After 100 times dilution the absorbance of the protein using one of the methods you used is 0.432. What is the concentration of the protein in that solution? It has been labelled as 20g/150mL. Is this value correct? Please use the table given below.

Water (mL)

BSA (mL)

Reagent (mL)

BSA conc (mg/mL)

Water (mL)

1 0.8 0.6 0.4 0.2 0

BSA (mL)

0 0.2 0.4 0.6 0.8 1

Reagent (mL)

5 5 5 5 5 5 Water (mL) 4 4 4 4 4 4

BSA conc (mg/mL)

Absorbance 0 .079 .132 .289 .412 .521

Explanation / Answer

First, for the samples prepared from the 400 mg/mL stock solution, you need to calculate the final concentration of BSA in each sample. These will be 0, 8, 16, 24, 32 and 40 mg/mL. (for the highest, the calculation is:
1 mL X 400 mg/mL / 10 mL = 40 mg/mL)

Then, plot the absorbances of those samples as a function of the concentration. You can do this on paper or in Excel or something like that.

After you insert a trend line, and get the equation of that line, you can use the absorbance of your unknown sample (0.432) to calculate protein concentration in that sample. Multiply that by 10 to get the mass of protein in 1 mL of that sample, and then by 100 to account for the dilution made. If that comes out to be something on the order of 133 mg/mL (=20000 mg / 150 mL), then the unknown protein solution was labeled correctly.

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.