Calculate percent recovery for each dye extract using the grape Kool-Aid spectrum as the starting value. Generically, percent recovery is calculated using this formula: % recovered = recovered amount/starting amount times 100% Since absorbance is directly related to concentration, the ratio of absorbances will be the same as the ratio of concentrations.
The Correct Answer and Explanation is :
Calculating percent recovery involves determining the efficiency of a process in retaining a substance after a procedure, such as dye extraction. The formula for percent recovery is:
Percent Recovery (%) = (Recovered Amount / Starting Amount) × 100
In the context of dye extraction, absorbance measurements can be utilized to estimate the concentration of dyes before and after extraction. According to the Beer-Lambert Law, absorbance (A) is directly proportional to the concentration (C) of a substance in a solution:
A = ε × l × C
Where:
- A is absorbance
- ε is the molar absorptivity coefficient
- l is the path length of the sample
- C is the concentration of the substance
Since ε and l are constants for a given substance and measurement setup, the ratio of absorbances before and after extraction reflects the ratio of concentrations, and thus, the percent recovery.
Steps to Calculate Percent Recovery Using Absorbance:
- Measure Initial Absorbance:
- Record the absorbance of the grape Kool-Aid solution at the wavelength corresponding to the maximum absorbance (A₀).
- Measure Final Absorbance:
- After the extraction process, measure the absorbance of the extracted dye solution at the same wavelength (A₁).
- Calculate Percent Recovery:
- Use the formula: Percent Recovery (%) = (A₁ / A₀) × 100
Example Calculation:
Suppose the initial absorbance (A₀) of the grape Kool-Aid solution is 0.8, and after extraction, the absorbance (A₁) of the extracted dye solution is 0.6.
Percent Recovery (%) = (0.6 / 0.8) × 100 = 75%
This indicates that 75% of the dye was successfully recovered during the extraction process.
Considerations:
- Ensure that measurements are taken at the same wavelength for both initial and final absorbance readings to maintain consistency.
- The Beer-Lambert Law assumes that the system adheres to linearity; deviations can occur at high concentrations or with complex mixtures.
- Matrix effects, such as interference from other substances in the solution, can affect absorbance readings. It’s important to account for these effects to obtain accurate recovery calculations.
By following these steps and considerations, you can effectively calculate the percent recovery of dyes in extraction processes using absorbance measurements.