1. What is the Van Deemter Equation?

Definition: The Van Deemter equation describes the relationship between plate height (H) and mobile phase velocity (u) in chromatography.

Purpose: It helps optimize chromatographic conditions by identifying the contributions to band broadening.

2. How Does the Calculator Work?

The calculator uses the Van Deemter equation:

Where:

• \( H \) — Plate height (m)
• \( A \) — Eddy diffusion term (m)
• \( B \) — Longitudinal diffusion coefficient (m²/s)
• \( u \) — Average mobile phase velocity (m/s)
• \( C \) — Resistance to mass transfer coefficient (s)

Explanation: The equation shows how different factors contribute to band broadening in chromatography columns.

3. Importance of Plate Height Calculation

Details: Lower plate height indicates better column efficiency. Understanding these parameters helps optimize chromatographic separations.

4. Using the Calculator

Tips: Enter all four parameters (A, B, u, C) with positive values (u must be > 0). The calculator will compute the theoretical plate height.

5. Frequently Asked Questions (FAQ)

Q1: What does each term in the equation represent?
A: A-term: Eddy diffusion from multiple flow paths; B-term: Longitudinal diffusion; C-term: Resistance to mass transfer.

Q2: How does mobile phase velocity affect plate height?
A: At low velocity, B-term dominates; at high velocity, C-term dominates. Optimal velocity minimizes H.

Q3: What are typical values for these parameters?
A: Varies by column, but A: 1-10 μm, B: 1-100 mm²/s, C: 0.01-1 s for analytical columns.

Q4: How is plate height related to column efficiency?
A: Lower plate height means more theoretical plates (N = L/H) and better separation efficiency.

Q5: Can this be used for both GC and LC?
A: Yes, though the relative importance of terms differs (B more important in GC, C more important in LC).