The basic principle of spectrophotometry is that every substance absorbs or transmits light at specific wavelengths, and the amount of light absorbed is directly related to the concentration of that substance in solution.
Explained simply:
When light passes through a solution:
- Some light is absorbed by the molecules.
- The remaining light passes through and is detected.
The spectrophotometer measures how much light is absorbed by the sample.
This information helps determine how much of the substance is present.
Based on the Beer-Lambert Law:
The principle follows the Beer-Lambert Law, which states that:
The absorbance of light is directly proportional to the concentration of the absorbing substance and the path length of the light through the solution.
So,
More concentration → more light absorbed.
Less concentration → less light absorbed.
In short:
Spectrophotometry works on the principle that light absorption by a substance is directly proportional to its concentration.
By measuring how much light a sample absorbs at a certain wavelength, we can find out how much of that substance is present.