Fluorescence spectroscopy is a powerful analytical technique that utilizes the phenomenon of fluorescence to identify and quantify molecules in a sample. In a fluorescence spectroscopy lab report, the focus is typically on the analysis of a specific compound or group of compounds using this technique. In this case, the compound of interest is quinine, which is a naturally occurring alkaloid that is commonly used as a medicinal agent to treat malaria.
The first step in a fluorescence spectroscopy lab report on quinine is to prepare the sample for analysis. This typically involves dissolving the quinine in a suitable solvent, such as water or methanol, and then filtering the solution to remove any impurities. The concentration of the quinine solution can then be determined using a suitable reference standard, such as a known concentration of a similar compound.
Next, the sample is irradiated with light of a specific wavelength that is absorbed by the quinine molecules. This causes the quinine molecules to become excited and emit light of a longer wavelength, which is known as fluorescence. The intensity of the emitted light is then measured as a function of the wavelength, which is known as the fluorescence spectrum.
The fluorescence spectrum of quinine is typically characterized by a strong peak at a wavelength of around 350 nm, which is known as the excitation maximum. The intensity of the emitted light at this wavelength is directly proportional to the concentration of quinine in the sample. Therefore, by comparing the intensity of the emitted light to a reference standard, it is possible to determine the concentration of quinine in the sample.
In addition to the excitation maximum, the fluorescence spectrum of quinine may also exhibit other peaks at longer wavelengths. These peaks are known as emission maxima and are typically caused by the presence of impurities or other substances in the sample that interfere with the fluorescence of quinine.
To conclude, fluorescence spectroscopy is a powerful analytical technique that can be used to identify and quantify quinine in a sample. By measuring the intensity of the emitted light as a function of wavelength, it is possible to determine the concentration of quinine and identify any impurities or interfering substances in the sample. This information is critical for the development and quality control of medicinal agents containing quinine, as well as for the study of the biological effects of this compound.
Quinine in Tonic Water with Fluorescence Spectroscopy
After vigorous stirring, the solution was transferred into a 1 L flask and diluted with distilled water to the mark. The graphical dependence of intensity on voltage is shown in Figure 2, from which it can be noted that the optimum value of PMT voltage was 700 V. After vigorous stirring, an additional amount of sulfuric acid was added until the mark was reached in 250 mL. The iron- phenanthroline complex intensely coloured and for analysis pH is not required to be kept under control but 3 are optimal. From the figures seen in the quinine measurements, define the quantity of quinine in the tonic beverage. To make this easier to understand, think of a rock being picked up.
We then set the spectrophotometer to a value of zero, using a blank containing buffer, H2O2, and Guaiacol Dye. The electrons must either jump to or fall back from one quantum level to another quantum level this is the quantum leap. The use of volumetric flasks and pipettes were essential in the transfer of Tonic water solution, especially in diluted solutions where the quinine concentration was in parts per billion. Furthermore, to examine the quantity of quinine within the series dilutions by monitoring the intensity of fluorescence that quinine produces. The chemical reaction of chemiluminescence releases energy that is absorbed by electrons in molecules. Commercial tonic water usually runs between 25 to 60 ppm quinine.
Ed, 52, 1975, 610. The overall process explained how fluorescence intensity was produced through the transition of valence electrons by a fluorescence source. This method is used to ensure that the equipment is within acceptable range for use. The data given are significantly different from the FDA standard, as reflected in equation 5. Quinine is a fluorescent compound with it being particularly fluorescent in acidic solution with its optimum being in the region of 3.
That was seen as chlorine had the lower quenching which corresponded with the values seen. The amount of light absorbed by a substance is directly in relation to the concentration of the solute and also the wavelength moving through the solute Jones et al. In the spectroscopy, the energy of excitation would enter the sample from the wavelength of the light source to the sample that was at low-energy state and become excited, or changed to its high-energy state. There are many different spectroscopic methods including circular dichroism, mass spectrometry, Raman, spectroscopy, nuclear magnetic resonance NMR spectroscopy, and ultraviolet-visible spectroscopy. There are several types of quenching is inner filter or more commonly known as concentration quenching which refers to when the concentration is increased causes a decrease in the fluorescence-per —unit- concentration. Raw Intensity Readings 0 6 2. Occasionally, excitation of an electron to a higher energy level can result in a triplet state T 1 unpaired electrons.
Experiment #3 Fluorescence Determination of Quinine
In part D the amount of quenching that quinine from the other compounds within the sample, namely Br and Cl, will be investigated. Absorbance is the measure of light intensity that is absorbed by a sample. Tonic beverage 977 910 977 955. What is the difference between internal and external heavy atom effect? The blank fluorescence was taken and then automatically subtracted from the intensity readings. Source Excitation monochromator Sample Detector Emission monochromator Figure 1 Figure 1.
A spectrophotometer is an instrument that shines a single wavelength of light of a known intensity into a solution and then measures the intensity of the light exiting the solution. Aniline is an example. Therefore, this trendline is not part of the linear range, but rather part of the working range, or the Calibration Range. Consult your textbook for a discussion of the relation between fluorescence intensity and concentration. Electrons can now return to the ground state by internal conversion, emitting heat through vibrational relaxation. Quinine is also a good example of a molecule which can undergo fluorescent quenching by the presence of other elements e. The external heavy atom effect appears in the case of heavy atoms halogens in the medium, which leads to the formation of a system of charge-transfer complexes and, consequently, to quenching of fluorescence.
Below is the calibration curve calculated from these 3 averages, including y-error bars from standard deviation. An excitation fluorescence spectrum is obtained in the opposite way. More specifically, the Agency set the upper limit for quinine in tonic water at 83 ppm 1. To the volumetric flasks add 0 of 10% hydroxylamine hydrochloride, 1 0% phenanthroline solution, 5ml of fresh diluted supplement before filling rest of volumetric flask with de ionised water. Among a large number of techniques, special attention should be paid to those that qualitatively describe the phenomena of luminescence. During this process, electrons are excited from their standard state. We as a group had four tubes labeled two, three, four, and five.
Be sure to point out what is held constant and what is plotted for each? Fluorometer Diagram Results All information in the following plots and tables is taken from the excel files included within this lab report. Its widely used for testing the sensitivity of the flourimetric method and used as a reference for the absolute quantum yield. They can also return to various vibrational energy levels of S o at a longer wavelength lower energy by fluorescence. Then it becomes evident that there is a linear dependence with the coefficient K between the concentration of the substance and the intensity of the emission registered by the spectrofluorometer. For this purpose, a sample of the calibration solution was placed in the cell of the apparatus and measured at a photomultiplier tube voltage range of 400 V to 800 V in increments of 50 V.
Determination of Quinine in Tonic Water (Fluorescence Spectroscopy).docx
It was important to do this right at the beginning of the lab since the zeroed value of the acid was the calibration number for all of the other solutions. Summary In this work, a spectrographic study of the concentration of quinine in tonic water samples was carried out using fluorescence. MATERIAL AND METHODS Reagents: The chemical used in this experiment was ammonium iron, Ethanol, Copper Nitrate3- hydrate, hydroxylamine hydrochloride, phenanthroline, potassium bromide, potassium iodide and sodium Procedures The experiment was carried out in accordance with laboratory manual CS351 pages 13 to 18 with the following with no deviation from the laboratory manual throughout the experiment. Aniline is an example. Last, in the tube labeled five we had a solution of 4.
Spectroscopy Laboratory Quinine in Tonic Water with...
This fluorescence graph was taken at 362 nm, as determined from figure 1. After that, tubes two and three were mixed together and tubes four and five were mixed together for a large solution of with a total of 8. Dependence of Quinine Fluorescence Intensity on the Concentration of Impurity Compounds: Potassium Bromide Orange and Potassium Iodide Yellow. Learn More In fact, quinine has several peaks responsible for different transitions. The prepared solutions were examined qualitatively using a spectrofluorometer to create a calibration curve and subsequently establish quinine concentration. All sample calculations can be found in the included duplicate lab notebook sheets attached to this report. To quantity of classes present amongst a sample, Beer-Lambert law can be used which states that under certain conditions concentrations of a species is proportional to the absorbance.
