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Fluorescence Process

FindingsThe findings for this experiment are displayed in the table and graphs below.

Conclusions and ImplicationsThe fluorescence accessory (spectrofluorometer) together with the Cary Concentration Application software can be used to successfully determine the amount of acetylsalicylic acid in a commercially available aspirin tablet.Average % of acetylsalicylic acid in one aspirin tablet =

66.47% ± 3.35%Fluorescence intensity is proportional to the number of fluorescing molecules in the sample, which would assume that a linear relationship exists between fluorescence intensity and concentration of the sample. Therefore, once the fluorescence is measured for each standard at each wavelength, a calibration curve can be constructed to determine the fluorescence vs. concentration. In practice however, this linearity is often absent and curvature is observed. A process called ‘self absorption’ is largely responsible for this curvature which occurs when the excitation and emission spectral envelopes overlap to a small extent. When this happens some of the emitted radiation is able to re-excite ground state molecules and is lost. The amount of self absorption increases with increasing concentration.

By: Wacey Lym Date: October 29, 2015

Scientific Research Poster Presentation

Literature Cited"The Fluorometric Determination of Acetylsalicylic Acid in an Aspirin Tablet." Truman.edu. Truman State University, 30

Aug. 2006. Web. 28 Apr. 2014. <http://chemlab.truman.edu/CHEM322manual/pdf/fluorimetry.pdf>.

Miles, Corbin I., and George M. Schenk. "Fluorescence of Acetylsalicylic Acid in Solution and Its Measurement in Presence of Salicylic Acid." ACS Publications. N.p., n.d. Web. 28 Apr. 2014. <http://pubs.acs.org/doi/abs/10.1021/ac60288a032>.

"Using 73 Series to Determine Aspirin Concentration." Using 73 Series to Determine Aspirin Concentration. N.p., n.d. Web. 28 Apr. 2014. <http://www.azom.com/article.aspx?ArticleID=10646>.

Standards & Crosscutting ConceptsHS-PS1-3. Plan and conduct an investigation to gather evidence to compare the structure of substances at the bulk scale to infer the strength of electrical forces between particles. This standard is directly related to this research because students would need to plan and conduct an experiment that would allow them to see relationships between electrical forces between particles such as emission and absorption. Patterns - different patterns may be observed at each of the scales at which a system is studied and can provide evidence for causality in explanations of phenomena. HS-PS3-3. Design, build, and refine a device that works within given constraints to convert one form of energy into another form of energy. This standard aligns with this project because students will use a form of energy to aid in calculations to determine another parameter. Students will measure the energy released through fluorescence and use that to determine concentrations and eventually lead to average mass percent in an aspirin tablet. Energy and Matter - changes of energy and matter in a system can be described in terms of energy and matter flows into, out of, and within that system.

Fluorescence of Acetylsalicylic Acid in an Aspirin Tablet

BackgroundFluorescence is the emission of light by a molecule in an excited electronic state. The phenomenon of fluorescence in most cases represents the energy emitted when a substance returns from an excited or higher energy state to its normal or lower energy state. Two types of information may be obtained when the fluorescence emission is studied:

1. The intensity wavelength distribution, which is an indication of the electronic structures of the molecule.2. The intensity at any wavelength where emission occurs which is an indication of the concentration of the fluorescent substance in the

solution. It is this second aspect of fluorescence that we are mainly concerned with when using the total fluorescence method of analysis. In the total fluorescence measurement, the sample is irradiated with radiation of a known wavelength and the fluorescence emission which occurs over the complete wavelength range is measured.

Research Question

With the use of fluorescent spectrometry, determine the amount of acetylsalicylic acid (aspirin) in over-the-counter aspirin tablets.