Question

Which of the following is not true for Eddy diffusion in chromatography?

• A. it is related to particle size, geometry and tightness of packing of the stationary phase
• B. it results in the broadening of the eluted band
• C. it is independent of flow rate
• D. it results from the tendency of the molecules to migrate from the concentrated center part of the band towards more dilute regions on either side

Hint:

Eddy diffusion is influenced by flow rate, particle size, and the packing of the stationary phase. Higher flow rates lead to more band broadening due to increased turbulence in the mobile phase.

Answer 1

The Correct Option is C

Step 1: Understanding Eddy diffusion.
Eddy diffusion refers to the spreading of solute particles in chromatography due to the differences in the flow paths taken by the particles in the mobile phase. This process leads to the broadening of the eluted band.
Step 2: Analyzing the options.

• (A) it is related to particle size, geometry and tightness of packing of the stationary phase: Correct. Eddy diffusion is strongly influenced by the physical properties of the stationary phase, such as particle size and packing geometry.
• (B) it results in the broadening of the eluted band: Correct. Eddy diffusion causes spreading of the solute molecules, which results in the broadening of the eluted band.
• (C) it is independent of flow rate: Incorrect. Eddy diffusion is dependent on the flow rate. Higher flow rates can cause more significant spreading and band broadening.
• (D) it results from the tendency of the molecules to migrate from the concentrated center part of the band towards more dilute regions on either side: Correct. This is the basic mechanism of diffusion that contributes to band broadening.

Step 3: Conclusion.
Eddy diffusion is not independent of flow rate. Therefore, option (C) is the correct answer, as it is not true. Final Answer:} it is independent of flow rate.