Determine absorption maxima of Paracetamol

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Learn how to determine absorption maxima of paracetamol with proper laboratory guide (requirements, principle, procedure, method and more).

Determine absorption maxima of Paracetamol

Absorption maxima are key indicators of the electronic transitions that occur within a molecule. When electromagnetic radiation interacts with a compound some certain wavelengths are absorbed by the molecule electrons and the absorption of light leads to the promotion of electrons from their ground state to an excited state. The absorption maxima correspond to the wavelengths of light that are most efficiently absorbed by the compound. To determine the absorption maxima of paracetamol, follow the laboratory guide.

Aim

To determine absorption maxima of Paracetamol.

Requirements
  • Paracetamol
  • Distilled water
  • UV visible spectrophotometer
  • volumetric flasks
  • Glass rood
Principle / Theory

Absorption of light by the sample depends upon the wavelength of light. When a substance shows the highest peak of absorption of light (wavelength) then it is known as Absorption maxima or Lambda max. Absorption maxima or lambda max is important for;

  • It provides electronic structure of compound.
  • It influences and follows Beer Lambert law.

This lambda max can be determined by the plotting a graph between absorption and wavelength.

Procedure

1.Preparation of stock solution

  • weigh 5mg paracetamol powder by using electronic balance.
  • Take the powder in 50ml volumetric flask.
  • Make up the mark of flask by adding distilled water.
  • Shake the volumetric flask until the powder disolved.

This solution is stock solution.

2.Praparation of working stock solution

  • Take 10 of stock solution.
  • Dilute upto 100 ml by using distilled water.

Method

  1. Use a spectrophotometer and adjust wavelength to 200 nm.
  2. In instrument reference level, use a cuvette which contain distilled water.
  3. Put the cuvette (contain prepared dilution) in the sample compartment.
  4. Record the absorbance.
  5. Repeat the step 3, but now increase the wavelength 200 nm to 400 nm.
  6. Record the absorbance of each wavelength setting.
  7. Plot a graph of absorption against wavelength.
  8. From the graph note down the wavelength of maximum absorbance for the solution
absorption maxima of Paracetamol
Report

Now write result like this: The absorption maxima of paracetamol is …..nm.

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