DrBob222, it is me again. Continue the question
5mL of a solution A (unknown concentration) was transferred into sic 25mL volumetric flask. The following volumes of a standard solution of A with with a concentration 75ppm were added to the flask: 0mL, 0.5mL, 1mL, 1.5mL, 2mL, and 2.5L. The excitation spectrum and and emission spectra is provided. Determine the unknown concentration of A in that solution?
I was given excitation spectrum of A and fluorescence spectra of solution #1 to #6
Thanks to your suggestion, my final answer is 7.48447 ppm (unknown concentration)
Thanks to your suggestion, so far my final answer is 7.48447 ppm (unknown concentration)
However, I am just wondering why Prof. gave the graph of excitation spectrum of A. One reason I can think of is that I use the highest intensity which is 100 and then plug it in the equation to find x. If I did that, my final concentration would be 70. Is it possible to do so
Furthermore, the second question is "If a synchronous experiment is to be performed, what would be the offset that you would use?
Thank you in advance for your help
I don't know the answer to your first question since I don't know what your prof had in mind. The information and questions after that is out of my league. I've never done any work with synchronous spectra; in fact, I don't know what it is. Sorry about that.
To determine the unknown concentration of A in the solution, the excitation spectrum and emission spectra were provided for different volumes of the standard solution with a known concentration of 75 ppm. By analyzing the fluorescence spectra and comparing them to the standard solutions, you were able to determine the unknown concentration as 7.48447 ppm.
Regarding your question about the excitation spectrum of A, it is provided to show how the intensity of the fluorescence response from A changes at different excitation wavelengths. The highest intensity point (100 in this case) on the excitation spectrum does not directly correspond to the unknown concentration of A. It is used as a reference point to determine the relative intensity of the fluorescence spectra at different excitation wavelengths.
To find the unknown concentration, you need to use the fluorescence intensity values obtained from the emission spectra of the different standard solutions. These values can be compared to their corresponding excitation wavelengths to create a calibration curve. By interpolating the fluorescence intensity of the unknown solution on the calibration curve, you can determine the corresponding concentration.
Regarding the second question about a synchronous experiment, in fluorescence spectroscopy, synchronous fluorescence can be used to simultaneously collect emission and excitation spectra at a fixed wavelength interval, known as the offset. The offset is the wavelength difference between the excitation and emission wavelengths.
To determine the appropriate offset for a synchronous experiment, you need to consider the characteristics of the sample and the desired information to be obtained. In general, it is recommended to choose an offset that provides a good resolution for the features of interest in the sample. This can be achieved by selecting an offset that minimizes the overlap between excitation and emission spectra, allowing for better discrimination and detection of specific fluorescence signals.
The specific offset value to be used in a synchronous experiment varies depending on the system and the properties of the sample being analyzed. It may require some experimentation and optimization to find the most suitable offset value for your specific analysis.
I hope this explanation clarifies your questions. Let me know if there's anything else I can help you with!