Analytical Chemistry Questions

Answer the following questions:

1) What variables can an analyst work with in order to optimize the UV analysis of a two-component mixture?

2) Discuss the interrelationship between specificity and sensitivity. What trade-offs are involved.

1)

UV spectroscopic method is based on the absorption of light which is directly proportional to the concentration of the absorbing medium and the thickness of the medium present in the path of the light.

Now, as per Lambert Beer’s law the following relationship holds good between absorbance (A) and transmittance (T)

A=log (Io/I) = Ecb;

Where A is the absorbance of the medium, E is the molar absorptivity (dm3 mol-1 cm-1) and c is the molar concentration (mol dm-3) and b being the path length (cm).

E is constant or specific for a light of certain wavelength. So, while conducting analysis with a light of monochromatic wavelength E can be considered to remain constant and therefore the variable that can be altered to attain the best possible result are (i) length of the absorbing medium, (ii) concentration of the medium. Also, the same analysis may also be tested with different wavelengths of light and in such a case E also becomes an operating variable that can help in optimizing the UV analysis of the mixture....

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