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.
Lab 7 fluorescence 2022
Pipet 5 mL of the diluted standard into a 25 mL volumetric flask and dilute to volume with 0 M H 2 SO 4. Spectroscopy is the analysis of spectra, typically light or mass spectra, where the spectrum of a source is used to determine the composition of a substance. The analyte was then changed from high-energy to low-energy state through the energy of emission which can be studied by the transition of valence electrons. There are many different spectroscopic methods including circular dichroism, mass spectrometry, Raman, spectroscopy, nuclear magnetic resonance NMR spectroscopy, and ultraviolet-visible spectroscopy. It fluoresces as the molecule between pH 5 and pH 13, below pH 5 it exists as the cation, and above pH 13 it exists as the anion; both do not fluoresce. Include the regression equation on the plot watch sig figs! Would the fluorescence measurements be affected if the source of quinine used to prepare the solutions were quinine hydrobromide? Fluorescence is highly sensitive method and can be used in many industries, including food analysis, pharmacy, and natural products.
Quinine in Tonic Water with Fluorescence Spectroscopy
We also made sure to determine our excitation and emission wavelengths. Below is the calibration curve calculated from these 3 averages, including y-error bars from standard deviation. The UV-vis light will then become absorbed by the chromophores. Linear Dependence of Fluorescence Emission on the Amount ppb of Quinine in a Series of Standard Solutions. In order to separate the emitted radiation from the incident beam the source , fluorescence measurements are made at right angles to the incident beam. Learn More Since fluorescence is a slow process, it is a highly undesirable way for a particle to dissipate excess energy, especially in energy states above the first level.
Learn More The nature of such luminescence can be due to various intramolecular mechanisms, one of which is the transition of an excited molecule from the lowest singlet vibrational level to the ground state. A spectrophotometer is an equipment used to take accurate measurement of absorbance at various wavelengths. Furthermore, it was shown empirically that the presence of heavy atoms in the mixture initiates quenching of the fluorescence, resulting in a consistent decrease in emission intensity. In other words, it is a picture of light rays after passing through a given substance. Reduction in intensity of fluorescence can be due to specific effects of constituents of the solution itself. Furthermore, just let the spectrophotometer act on the solution for the desired length of time while recording the data at each specific… Glow Sticks Chemiluminescence is what happens in glow sticks. Commercial tonic water usually runs between 25 to 60 ppm quinine.
The relationship between concentration and fluorescence intensity is dependent on several factors. Types of quenching include concentration quenching a decrease in the fluorescence per unit concentration as the concentration is increased , also referred to as an inner filter effect, collisional quenching and chemical quenching. Are there any disadvantages to the fluorescence technique? We created our first five standards to determine if our tonic sample would fall within our given curve. When a person picks up a heavy rock, it takes energy, just as it takes energy for an electron to jump to a higher energy level. Once the initial concentration was calculated of Fe3+, NCS and FeNCS2+ in molarity. In particular, fluorometers require an external EMR source, whereas a chemical reaction initiates chemiluminescence.
[PDF] Fluorescence Determination of Quinine in Tonic Water Experiment
There are two laws surrounding the absorbance of light in a solution known as the Beer-lambert relationship. In addition, a chemiluminescence spectrometer does not require a set wavelength setting, and since this type, unlike fluorescence, is not multi-wavelength selective, an output wavelength recorder is not required. A UV-Vis spectrophotometer measures absorbance, which is related to the transmittance of light through a solution. Assuming that all of the molecules are in the ground state before excitation, the least energy absorbed in the excitation process i. What is the reason for this phenomenon? As for the quinine, which was of course used in the experiment, is susceptible to quenching from chloride ion.
This is the wavelength at which the two graphs intersect. Ed, 52, 1975, 610. Rather than recording the light absorbed by a species, or the light necessary to excite its electrons, we measure the light emitted after the species has been excited and returns to its ground electrical state. A series of five mixtures with different working solution concentrations was created by adding 0. The wavelengths of light incident on the sample are varied with the excitation monochomator and the wavelengths of light emitted by the sample are investigated with the emission monochromater. A spectrophotometer was used in the lab to determine these values.
These laws state that the absorption of light is exponentially related to the concentration of the solute. 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. As the electron returns to the lower state, it releases the energy as a photon of light; the photon is the light that we see. Substituents such as -OH, -OCH 3, and -NH 2 which are electron donating groups can enhance fluorescence. On the other hand, emission spectra constant wavelength arise when electrons, atoms, particles, or fragments of molecules being excited, go from a higher energy state to a lower energy state. For example, aniline fluoresces as the molecule between pH 5 and pH 13.
Experiment #3 Fluorescence Determination of Quinine
That is, by scanning the excitation monochromator while holding the emission monochromator at a fixed wavelength. Aniline is an example. To vary the total intensity of the light and avoid saturating or overloading the detector you will also vary the slit widths for the excitation and emission slits stars as well as the gain on the detector. In the tube labeled two we had a solution of 2. Reduction in intensity of fluorescence can be due to specific effects of constituents of the solution itself. Introduction UV-visible spectroscopy is a method which uses light, both visible and ultraviolet to measure the absorption of spectroscopy in U- Vis spectral regions. Aniline is an example.
