Can anyone help me with this question.
Propose a method in detail to determine the concentration of two components, quinine and anthracene in a mixture using fluorimetry. You have access to pure sulutes and an appropriate solvent.
The excitation and emission spectra of quinine and anthrancene are given
Without any data all I can do is get you started generally. Use the excitation spectra of each to determine the wavelength to use for excitation (either at the same time or in separate runs), then use the fluorescent data (emission data) to determine the wavelength to use to read the output. You will then want to set up standard curves, plot A vs C for each.
Thank you so much DrBob222. Thanks to your suggestion, I come up with this answer:
The wavelength of quinine to use for excitation is 250nm and 350nm and for emission is 470nm. The wavelength of anthracene to use for exciation is 350nm and for emission is 400nm. However, what do you mean "set up standard curves"? If I need to plot A vs C, I need to know concentration, but how can I suppose to find concentration?
You prepare standard solutions of anthracene and quinine in the range you expect unknowns to be, go through your procedure, measure the fluorescence of each standard and plot that [I guess you don't call it A if it is emitting :-)] against the concn to get a standard curve. Since the problem specifically states that you want the method for quantitatively determining the two components, I think you must include the part about preparing the standards and preparing the working curve.
I came up with this answer, can you possibly help me to check it?
- Calibration standards:
+ We prepare standard solutions of anthrancene and quinine solution in the range of concentration we expect. We dilute to the mark with water in volumetric flask. (We do 5 samples for each)
+ Record ultraviolet spectrum of each of the 10 standards with water in reference cuvet. Not the wavelengthof peak absorbance for quinine (in this case: 250 and 350) and the wavelength of peak absorbance of anthrancene (in this case 350). Then we prepare calibration graphs of absorbance vs concentration on each compound at 250 and 350. We take 3-4 replicates readings for each standard.
+ We prepare the unknown. Then we measure the ultraviolet absorption. With the absorbance at 250 and 350, we can find the concentration of quinine and anthrancene.
That is my answer. However, I do not know why I have to use the fluorescent data to determine the wavelength to use to read the output? That wavelength of emission for quinine is 470 and for anthrancene is 400. Do I need to include it in my answer?
Certainly! To determine the concentration of quinine and anthracene in a mixture using fluorimetry, you can follow these steps:
1. Prepare a calibration curve for each component separately: Start by preparing a series of standard solutions with known concentrations of quinine and anthracene. These standards should cover a range of concentrations that you expect to find in your mixture. Measure the fluorescence intensity of each standard solution using a fluorimeter, noting the excitation and emission wavelengths used.
2. Collect excitation and emission spectra of the mixture: Using the fluorimeter, collect the excitation and emission spectra of the mixture containing quinine and anthracene. These spectra will help you select the appropriate excitation and emission wavelengths for further analysis.
3. Determine the excitation and emission wavelengths: From the collected spectra, identify the excitation and emission wavelengths that provide the highest fluorescence intensity for each component (quinine and anthracene). These wavelengths will be used for subsequent measurements.
4. Prepare the mixture sample: Create a sample solution by dissolving a known mass or volume of the mixture in an appropriate solvent. Ensure that the sample is well-mixed and homogenous.
5. Set up the fluorimeter: Set up the fluorimeter, ensuring that it is calibrated and properly aligned. Set the excitation and emission wavelengths according to the values identified in step 3.
6. Measure the fluorescence intensity: Place the prepared mixture sample in the fluorimeter and measure the fluorescence intensity. Record the obtained intensity value.
7. Calculate the concentration: Using the calibration curves prepared in step 1, interpolate the concentration of each component (quinine and anthracene) from the measured fluorescence intensity obtained in step 6. This can be done by comparing the fluorescence intensity value to the corresponding calibration curve.
8. Verify the results: To ensure accuracy, it is recommended to perform replicate measurements and calculate the average concentration values of each component.
By following these steps, you can determine the concentration of quinine and anthracene in a mixture using fluorimetry.