MassQC Help > Metrics > Chromatography > Peak Width          
Peak Width

Peak Width of a chromatographic peak is the peak's full width at half maximum.

Peak Width

Lower peak widths indicate better chromatographic resolution.

The Peak Width metric used by MassQC is the median of the peak widths for all the identified peptides. An increase in the median peak width means that most of the peaks are getting wider.


Seconds (s)


Lower: Narrow peaks means better chromatographic resolution.

The most reproducible LC-MS performance is when this metric remains in a narrow range over a series of runs. Wide variability in any metric means your process is not reproducible.

What the Metric Detects:

An increase in Peak Width means broader LC peaks.

A gradual increase in Peak Width over weeks may mean that the LC column needs to be replaced.

An abrupt change in the Peak Width from the previous run may indicate bleeding or tailing of the LC peaks caused by a dirty or warn out column.

Related Metrics:

The Peak Width metric will not detect a broadening of only a few peaks. The Peak Width Variability metric detects the case where the average peak stays the same but some peaks get dramatically wider. An increase in both the Peak Width and Retention Spread metrics is common when the gradient length has been increased either by changing the LC method or induction by a problem with the chromatography system.

Some metrics are also correlated. When the Peak Width metric increases usually the number of MS2 Spectra also increases but so does Oversampling. In addition, a wider Peak Width usually means that the Peak Intensity, MS2 Signal to Noise, Search Score and Peptides per Minute metrics have decreased. It might be worth investigating if these metrics don't behave in this way.

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