Peak & Mass

Analytical methods, made visual

Interactive HPLC Chromatogram: Peak Resolution and Detector Response

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Chromatogram peak explorer

Move the peaks apart or broaden them to see how their overlap changes. The curves are simulated with two Gaussian peaks of equal width and different heights.

Solid line combined signal · Dashed lines individual peaks

Model resolution Rₛ is 1.14.

Resolution is Rₛ = 2(t₂ − t₁) / (w₁ + w₂), where t is the peak’s retention time and w is its baseline width. This Gaussian model approximates each baseline width as 4σ. The result describes the simulated peaks only.

Compare the two model traces

Both fictional chromatograms plot relative detector signal in arbitrary units (AU) against time in minutes. The dashed curves show the individual components, with a longer dash for peak 1. The solid line shows their summed signal.

024681000.511.5 Retention time (min) Relative signal (AU)
Trace A · Wider separation. Rₛ = 1.14.
024681000.511.5 Retention time (min) Relative signal (AU)
Trace B · Overlapping peaks. Rₛ = 0.36.
Synthetic peak parameters and integration basis
TracePeak centers tR (min)Shared σ / baseline width (min)Component areas (AU·min)Model Rₛ
A · Wider separation3.00 / 4.600.35 / 1.400.8773 / 0.61411.14
B · Overlapping peaks3.00 / 3.500.35 / 1.400.8773 / 0.61410.36

The model uses Gaussian peaks with heights of 1.00 and 0.70 AU. The baseline-width convention is 4σ. The areas integrate each full modeled component, using height × σ × √(2π). Trace B has the same component areas by construction. An analyst working from its combined signal would need a justified way to separate them before reporting individual areas.

Try different UV responses with separated peaks

Keep the amounts at 90 and 10 arbitrary amount units. With separated peaks and a linear detector, the modeled area is amount × relative response factor. Peak 1 has a fixed factor of 1.

At a factor of 0.5, modeled areas are 90 and 5. Peak 1 accounts for 94.74% of the total area.

Fixed amounts, different response factors
AmountsResponse factorsModeled areasPeak 1 area share
90 / 101 / 190 / 1090.00%
90 / 101 / 0.590 / 590 ÷ (90 + 5) × 100 = 94.74%