Peak Asymmetry Calculator Formula

Understand the math behind the peak asymmetry calculator. Each variable explained with a worked example.

Use the Peak Asymmetry Calculator

Formulas Used

Asymmetry Factor (As)

asymmetry = b_width / a_width

USP Tailing Factor (Tf)

tailing = (a_width + b_width) / (2 * a_width)

Variables

VariableDescriptionDefault
b_widthBack Half-Width at 10% Height (B)(mm)6
a_widthFront Half-Width at 10% Height (A)(mm)5

How It Works

Peak Asymmetry and Tailing Factor

Peak shape is a critical quality attribute in chromatography. Asymmetric peaks indicate column problems or unwanted secondary interactions.

Formulas

Asymmetry Factor: As = B / A (measured at 10% height)

USP Tailing Factor: Tf = (A + B) / (2A) (measured at 5% height, but often approximated at 10%)

  • As = 1: perfectly symmetric
  • As > 1: tailing (common with silanol interactions)
  • As < 1: fronting (often from column overload)

    • Worked Example

    A peak with front half-width A = 5 mm and back half-width B = 6 mm at 10% height.

    b_width = 6a_width = 5
    1. 01As = 6 / 5 = 1.200
    2. 02Tf = (5 + 6) / (2 × 5) = 11 / 10 = 1.100
    3. 03Slight tailing (acceptable; As < 1.5 is typically OK)

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