Transcript Overview of Injury Research - SEAS

Effect of pH on Aspirin Dissolution
Group 101-2B
Aims/Objective & Hypotheses:
-To determine the optimal pH for dissolution for aspirin
(acetylsalicylic acid) using gravimetric analysis.
-The pH levels of 1,2,3,5,6,7, and 8 chosen represent the pH
levels of different regions along the digestive tract.
- It is hypothesized that aspirin will have optimal dissolution at
pH of 1-3, which corresponds to that of the stomach.
University of Pennsylvania
Department of Bioengineering
Methods and Protocol:
•Dissolve 200mg of aspirin powder in 100mL of buffer solution for 20min.
Buffer solutions have pHs set at 1, 2, 3, 5, 6, 7, and 8
•Separate the dissolved solution from the undissolved aspirin with filter
paper and dry.
•Weigh the mass of undissolved aspirin and calculate the percentage
mass dissolved.
Equipment:
Magnetic stirrer & stirring bar
Filter paper
Oven
Electric beam balance
Buffer solution
Aspirin powder
University of Pennsylvania
Department of Bioengineering
Proposed Results/Findings/Deliverables:
•Solubility increases as pH decreases; and the optimal pH is
in the range 1-3, which is the pH of the stomach.
• The amount of dissolved aspirin against the time will give
the rate of dissolution at each pH.
•According Bayer HeathCare, dissolution occurs in the
stomach, but absorbs in the small intestine.
stomach pH: 1-3
small intestine: pH 6-8
For this reason we propose that the aspirin should take less
time to completely dissolve (lower rate of dissolution) at a
low pH level (stomach).
University of Pennsylvania
Department of Bioengineering
Potential Pitfalls:
•Time allowed for dissolution (20 min) is too short for enough
aspirin to dissolve. This might show that there is no significant
difference among the different pHs even if there may be.
•The effects of solutions with two different pHs cannot be
compared if all 200 mg of aspirin dissolved completely in both.
•Optimal pH is out of the range that we test.
University of Pennsylvania
Department of Bioengineering
Materials and Budget & Justification:
• 500mL of buffer solution with pH 1,2,3,5,6,7, and 8 from Fischer Chemical:
$162.84
• 1lb of aspirin powder from Vedco: $9.95
• Fine porosity quantitative grade filter paper from Fischer Scientific: $8.85
Total: $181.64
University of Pennsylvania
Department of Bioengineering