Calculating Proline Concentration Using Beer-Lambert Law

This question requires calculating the concentration of a proline ninhydrin complex using the Beer-Lambert Law.

Beer-Lambert Law Principle

The Beer-Lambert Law relates the absorbance of a solution to the concentration of the analyte and the path length the light travels through the solution. The formula is:

$A = \epsilon lc$

Where:

• A is the absorbance (unitless)
• \(\epsilon\) is the molar extinction coefficient (in $\mu$M$^{-1}$Cm$^{-1}$)
• l is the path length of the cuvette (in cm)
• C is the concentration of the analyte (in $\mu$M)

Given Information

• Absorbance, A = 0.68
• Molar extinction coefficient, \(\epsilon\) = 0.34 $\mu$M$^{-1}$Cm$^{-1}$
• Path length, l = 1 cm

Calculation Steps

1. Rearrange the Beer-Lambert Law formula to solve for concentration (C):

   $C = \frac{A}{\epsilon l}$

2. Substitute the given values into the rearranged formula:

   $C = \frac{0.68}{0.34 \, \mu \text{M}^{-1}\text{Cm}^{-1} \times 1 \, \text{cm}}$

3. Calculate the concentration:

   $C = \frac{0.68}{0.34} \, \mu \text{M}$

   $C = 2 \, \mu \text{M}$

Result

The concentration of the proline is 2 $\mu$M. This corresponds to Option 4.