Resolution (Chromatography) Calculator Formula

Understand the math behind the resolution (chromatography) calculator. Each variable explained with a worked example.

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Formulas Used

Resolution (Rs)

resolution = 2 * abs(tr2 - tr1) / (w1 + w2)

Variables

VariableDescriptionDefault
tr1Retention Time Peak 1 (tR1)(min)5.2
tr2Retention Time Peak 2 (tR2)(min)5.8
w1Peak Width at Base 1 (w1)(min)0.3
w2Peak Width at Base 2 (w2)(min)0.35

How It Works

Chromatographic Resolution

Resolution quantifies how well two adjacent peaks are separated. It combines the effects of selectivity, efficiency, and retention.

Formula

Rs = 2 × (tR2 - tR1) / (w1 + w2)

where tR is retention time and w is peak width at the base (4-sigma width for Gaussian peaks).

  • Rs < 1.0: peaks overlap significantly
  • Rs = 1.0: about 4% overlap
  • Rs = 1.5: baseline separation (< 0.3% overlap)
  • Rs >= 2.0: complete separation

    • Worked Example

    Two peaks at 5.2 and 5.8 min with base widths of 0.30 and 0.35 min.

    tr1 = 5.2tr2 = 5.8w1 = 0.3w2 = 0.35
    1. 01Rs = 2 × (5.8 - 5.2) / (0.30 + 0.35)
    2. 02Rs = 2 × 0.6 / 0.65 = 1.2 / 0.65 = 1.846
    3. 03Baseline separation achieved (Rs > 1.5)

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