1. What is Width of Peak given Number of Theoretical Plates and Retention Time?

Definition: This calculator determines the width of a chromatographic peak at its base using the retention time and number of theoretical plates.

Purpose: It helps in chromatographic analysis to evaluate peak shape and column efficiency.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( w \) — Width of the peak at its base (seconds)
• \( t_r \) — Retention time of the peak (seconds)
• \( N \) — Number of theoretical plates (dimensionless)

Explanation: The width of the peak is directly proportional to the retention time and inversely proportional to the square root of the number of theoretical plates.

3. Importance of Peak Width Calculation

Details: Peak width is crucial for determining resolution between adjacent peaks and assessing column efficiency in chromatographic separations.

4. Using the Calculator

Tips: Enter the retention time in seconds and the number of theoretical plates. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the significance of the number 4 in the formula?
A: The factor of 4 accounts for the fact that peak width is typically measured at the baseline, which is approximately 4 standard deviations of the Gaussian peak.

Q2: How is the number of theoretical plates determined?
A: The number of theoretical plates (N) is calculated from the retention time and peak width using: \( N = 16(t_r/w)^2 \).

Q3: What does a narrower peak indicate?
A: Narrower peaks (smaller width) generally indicate better column efficiency and higher resolution between adjacent peaks.

Q4: Can this formula be used for non-Gaussian peaks?
A: The formula works best for symmetrical (Gaussian) peaks. For tailing or fronting peaks, alternative methods may be needed.

Q5: How does retention time affect peak width?
A: For a given number of theoretical plates, peaks with longer retention times will be wider due to longitudinal diffusion.