Question

A protein solution gives absorbance of 0.34 at λ280 using 0.5 cm path length cuvette. Given the extinction coefficient of the protein is 3.4 × 10³ M⁻¹ cm⁻¹, the concentration of protein in the solution in mM is ....... (decimal digits up to 2 places)

Hint:

To calculate concentration using Beer's Law, remember that absorbance is proportional to concentration and path length.

Answer 1

Correct Answer: 0.19

Step 1: Use Beer's Law.
Beer's Law is given by: \[ A = \epsilon \times c \times l, \] where \( A \) is absorbance, \( \epsilon \) is the extinction coefficient, \( c \) is the concentration, and \( l \) is the path length.

Step 2: Rearrange the formula.
To find the concentration, rearrange Beer's law: \[ c = \frac{A}{\epsilon \times l}. \]

Step 3: Substitute the values.
Substitute the given values into the equation: \[ c = \frac{0.34}{(3.4 \times 10^3) \times 0.5} = \frac{0.34}{1700} = 0.0002 \, \text{M} = 0.02 \, \text{mM}. \]

Step 4: Conclusion.
The concentration of protein in the solution is 0.02 mM.