University of Pennsylvania Department of Bioengineering Aims/Objective & Hypothesis: SPECTROANALYSIS OF ACETYLSALICYLIC ACID CONTENT IN ASPIRIN - TB4 The aim of the experiment is to find the amount of acetylsalicylic acid in an original full-dose Bayer aspirin tablet by UV spectroanalysis and to compare the difference between the empirically measured amount, and the advertised amount of 325mg of acetylsalicyclic acid in the tablet. The null hypothesis states that there is no difference in the measured amount and the advertised amount of acetylsalicyclic acid, with a tolerance of 5%. The alternative hypothesis states that there is a difference between the measured and advertised amounts.

University of Pennsylvania Department of Bioengineering Methods, Protocol & Equipment: Proposed Protocol and Methods: Prepare 5 samples of pure acetylsalicylic acid solutions of 2.0 mg/ml, 1.8 mg/ml, 1.6 mg/ml, 1.4 mg/ml, 1.2 mg/ml, 1.0 mg/ml. Serially dilute each of these samples by a factor of 2 to get five additional solution samples of 1.0 mg/ml, 0.9 mg/ml, 0.8 mg/ml, 0.7 mg/ml, 0.6 mg/ml, 0.5 mg/ml. Run the 10 samples through the spectrophotometer and construct an aqueous standard curve. Dissolve 1 Bayer aspirin tablets in 250 ml distilled de-ionized water and create 10 aliquots of the sample. Run Sample 1 through the spectrophotometer (unspiked). Then add pure acetylsalicylic acid of known mass to samples 2-9 and run in spectrophotometer. Repeat the procedure for the remaining 49 tablets and construct absorbance curves. Use method of addition to find out the actual amount of acetylsalicylic acid in each tablet. Use a 1-sample Z-distribution hypothesis test to see if there is a difference between the measured and advertised amounts.

University of Pennsylvania Department of Bioengineering Proposed Results/Findings/Deliverables: Potential Pitfalls: The standard additions method is applied to the absorbance vs. concentration curves to determine the concentration of acetylsalicylic acid in the aspirin tablet. The slope of the spiked sample is expected to differ from the slope of the aqueous standard. When extrapolated to the x-intercept, the spiked sample curve will reveal the concentration of the acetylsalicylic acid in a tablet. The acetylsalicylic acid amount measured falls within 5% of the advertised value, thus supporting the null hypothesis. The measured amount of acetylsalicylic acid may have deviated from the advertised amount due to physical loss (chipping) of aspirin tablet from handling. Inaccuracies in serial dilutions, pipet volume uncertainty, and mass measurement uncertainty.

University of Pennsylvania Department of Bioengineering Materials and Budget & Justification: Equipment and materials: Ultraviolet (UV) Spectrophotometer – Spectronic Genesys 5 40 original full-dose Bayer Aspirin tablets 40 4ml cuvettes De-ionized water Pure acetylsalicylic acid ml volumetric flasks Parafilm P1000 Pipetteman Justification: We need a UV spectrophotometer because the optimal wavelength at which the ring structure in acetylsalicylic acid absorbs light is 250nm, which is in the UV region. A sample size of 40 was chosen such that the results could be approximated to a Z distribution by the Central Limit Theorem.