MassQC Help > Metrics > Dynamic Sampling > Oversampling          

Oversampling is the fraction of all peptides that have been identified by more than one spectra.

Repetitive acquisition of the same peptides can indicate that the dynamic sampling settings on the instrument need to be adjusted.


Percent (%)


Lower: A high value of Oversampling indicates that you are sampling the same peptide over and over rather than sampling different peptides. In the experimental setup where spectra counting is used to estimate the protein quantities, the ideal level of Oversampling may be different than in the experimental setup where the emphasis is on detecting as many different peptides as possible.

Note that some repetitive sampling can be good if the sample that will be run after the standard is expected to have a much higher peptide density (higher concentration) than the standard itself.

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:

If Oversampling changes it may mean that the sampling parameters in the method such as trigger level, dynamic exclusion list length or dynamic exclusion time have changed.

Related metrics:

If too much sample is loaded on to the column, then Oversampling may increase. In this case Total Ion Current might be expected to also increase.

Related Troubleshooting Topics:

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