To determine the percentage of aspirin in different commercial preparations and to find which is the best value for money
2. Hypothesis
The greater the percentage of acetylsalicylic acid (ASA) in the tablet, more powerful and efficient the aspirin would be due to the way aspirin works in human’s body. Aspirin is often used to alleviate the pain, and the sensation of pain is mainly attributed to a chemical substance called prostaglandins, which is responsible to send a strong signal to the brain to remind the damage of the body. Working cells in the damaged area produce prostaglandins using an enzyme called cyclooxygenase 2 (COX-2), and aspirin works by disturbing COX-2 functions. By doing so prostaglandins are no more produced, and the pain is revealed while the body damage still exists. Therefore it indicates that the more amount of acetylsalicylic acid (ASA) being taken, the more COX-2 enzymes become unavailable of producing prostaglandins and the weaker the signals are sent to the brain, which result in less pain. For this reason, it is very likely to be the percentage of acetylsalicylic acid (ASA) affecting the efficiency of aspirin, and this could be proved through simple neutralization reaction by titration with basic solution, such as sodium hydroxide. The more sodium hydroxide needed in the titration, the more the amount of ASA in aspirin, thus the more powerful the aspirin is.
The equation would be:
C6H5OCOCH3COOH+NaOH → C6H5OCOCH3COONa++ H2O
As the percentage purity of the aspirin is calculated, the value should be compared to its price per gram. The table below shows three different brands and their price.
Brand | Package (g) | Price (RMB) | Bamyl | 10 tablets × 0.5g | 6 | Bayer | 30 tablets × 0.1g | 20 | Baijunyu | 100 tablets × 0.025g | 20 |
The table below shows the price for each brand per gram, to compare with the percentage purity after the experiment.
Brand | Price per gram (RMB/g) | Bamyl | 6÷10