How is colorimetry used in aspirin?
The amount of 2-hydroxybenzoic acid in a solution made by hydrolysing aspirin can be determined by adding iron(III) ions and measuring the intensity of the violet-blue solution. From this the amount of aspirin can be calculated. Colorimeter and suitable filter (green/yellow).
What wavelength does aspirin absorb at?
265 nm
The absorption spectra of aspirin and salicylic acid in phosphate buffer (pH 6.8) are shown in Fig. 1. The absorption peaks were at 233 nm and 296 nm. At the wavelength of 265 nm, aspirin and salicylic acid had a different absorbance, so it affected the determination of dissolution rate.
How can you detect impurities in aspirin?
Because today’s aspirin is mass produced in tablet form, Spectrophotometers are a reliable and economical way to keep the purity of Aspirin consistent throughout the manufacturing process. The purity and amount of acetylsalicylic acid in aspirin can be measured using a Visual Spectrophotometer.
How do you measure aspirin content?
Aspirin is a weak acid that also undergoes slow hydrolysis; i.e., each aspirin molecule reacts with two hydroxide ions. To overcome this problem, a known excess amount of base is added to the sample solution and an HCl titration is carried out to determine the amount of unreacted base.
What is colorimetric titration?
Titration is a kind of volumetric measurement, whereby you measure the unknown indirectly by adding another chemical or reagent that will react with it to make a visible change. This approach is called colorimetric titration because you measure your progress through the use of a change in color.
What does a colorimeter show?
1 Colorimeters. A colorimeter can measure the absorbency of light waves. A colorimeter is an instrument that compares the amount of light getting through a solution with the amount that can get through a sample of pure solvent.
What is the spectrophotometric analysis of aspirin?
SPECTROPHOTOMETRIC ANALYSIS OF ASPIRIN. Introduction: A colored complex is formed between aspirin and the iron (III) ion. The intensity of the color is directly related to the concentration of aspirin present; therefore, spectrophotometric analysis can be used.
What effect does the coating of aspirin tablets have on the hydrolysis of aspirin?
Enteric coating prevents tablets from hydrolysis while core being in uncoated form immediately degrades into salicylic acid. For both type of aspirin tablets the extent of degradation depend upon humidity level and time.
What are the main special impurities in aspirin?
The known impurities of ASP are already reported, which includes salicylic acid, salsalate (salicylsalicylic acid), acetylsalicylsalicylic acid, 4-hydroxybenzoic acid, 4-hydroxyisophthalic acid and acetylaalicylic anhydride (3, 4).
Why is salicylic acid an impurity in aspirin?
Salicylic acid contains a phenol group, but acetylsalicylic acid does not. Therefore, if you add FeCl3 to an aspirin sample and you see a purple color, it means that there is still some salicylic acid present and the sample is impure. The aspirin collected will then be purified by recrystallization.
Why is aspirin used?
Aspirin is used to reduce fever and relieve mild to moderate pain from conditions such as muscle aches, toothaches, common cold, and headaches. It may also be used to reduce pain and swelling in conditions such as arthritis. Aspirin is known as a salicylate and a nonsteroidal anti-inflammatory drug (NSAID).
What is titration of aspirin?