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An electropherogram peak area is the time integral of detector signal above an assigned baseline over a specified peak interval:Its units are signal multiplied by time. It differs from peak height and from the amount of material unless a detector-response and transport model connects them. Broadening a peak can lower its height while preserving its area.

For an isolated Gaussian distribution of signal, $s-b=H\exp [-(t-t_m{)}^2/(2{\sigma }_t^2)]$, integration over the complete peak gives $A_p=H{\sigma }_t\sqrt{2\pi }$. An original peak with $H=2$ signal units and ${\sigma }_t=3$ s has area $15.04$ signal-seconds. Doubling the width at unchanged area halves the height. Integrating only a finite interval loses the corresponding tails; integrating overlapping peaks can include another species' response.

Why can migration time enter quantification? Suppose a concentration-sensitive detector gives $s-b=kc$ for a band moving at constant speed $v$ through a capillary of internal area $S$. The amount passing the detector isSince $v=L_d/t_m$, $n\propto A_p/t_m$ at fixed $S$, $L_d$ and response coefficient $k$. A slow band spends longer in the detection window and can have more raw time-integrated signal for the same amount. This motivates time-corrected electropherogram peak area; the first-party software explicitly calculates it as raw area divided by migration time.^[ref]

For stipulated raw areas 120 and 180 signal-seconds at migration times 200 and 300 s, both corrected values are 0.60 signal units. Equal corrected values imply equal modeled amounts only if the relevant response coefficients and sampling conditions agree. Different species need not have equal detector responses, and a detector measuring a different physical observable requires its own model.

Baseline error has an especially simple consequence. If the estimated baseline exceeds the true one by $\delta b$ throughout a window of duration $T$, the area error is $-\delta bT$. A 0.01 signal-unit offset over 60 s subtracts 0.60 signal-seconds. Blank measurements, explicit integration limits and inspection of unresolved neighbors therefore matter even when the numerical integration itself is exact.

A time-corrected electropherogram peak area is a raw electropherogram peak area divided by its migration time,It compensates for the longer passage time of a slower band through a concentration-sensitive detector in capillary electrophoresis. The first-party processing documentation defines this quantity explicitly and computes a percentage by dividing each corrected area by the sum of corrected areas.^[ref]

The transport model explains the correction. If the baseline-subtracted detector signal is $kc(t)$, internal capillary area is $S$ and band speed through the window is constant $v$, thenWith detector distance $L_d$ and $v=L_d/t_m$,Thus dividing the time integral by migration time removes one speed dependence. It does not determine the response coefficient $k$, injected sample amount or chemical identity.

For an original example, two peaks have raw areas 90 and 150 signal-seconds and migration times 150 and 300 s. Their corrected areas are 0.60 and 0.50 signal units. With equal detector response coefficients, their modeled relative amounts are $6:5$, giving $54.55\%$ and $45.45\%$ of the corrected total. Raw-area normalization would instead give $37.5\%$ and $62.5\%$.

Species-dependent detector response remains important. If the first coefficient is twice the second, amounts are proportional to $0.60/2$ and $0.50/1$, giving $37.5\%$ and $62.5\%$ instead. Equal normalized corrected areas therefore need not mean equal amounts when the detector responds differently to the species. A measurement calibration must match the response and sample conditions being interpreted.

The reduction also assumes each band travels at a representative constant speed. If the electric field or electroosmotic flow changes substantially during a run, $L_d/t_m$ is an overall migration speed and need not equal the speed during detection. Baseline error, unresolved neighbors and nonlinear detector response are likewise not repaired merely by dividing by time. The software's chosen migration-time definition is part of the calculation: its CE mode uses the peak apex, while its CIA mode uses the midpoint of the start and end times.^[ref]