MassQC Help > Metrics > Ion Source > Percent +1H          
Percent +1H

Percent +1H tells the percentage of all spectra ions with a charge of +1.

Higher percentages of +1H spectra may indicate inefficient ionization in the electrospray.

Percent +1H is calculated by looking at the charge state of all spectra that match to a peptide.


Percent (%)



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:

A high Percent +1H means that there are an unusual number of +1 ions. This might mean that the peptides are not ionizing efficiently and so are not getting doubly charged as is normal in electrospray.

It might also mean that a large number of polymer or other contaminate ions are in the sample. These molecules may preferentially ionize as charge +1.

Related metrics:

Large Percent +1H means that the other charge states don't get as many ions. The metrics Percent +3H and Percent +4H also report the ion's charge state. Any ions that are not charge +1, +3, or +4 are probably charge +2.

If the distribution of charge differs, it may affect the size of the peptides that are detected. Another way to look at this is with the metric Precursor m/z.

Related Troubleshooting Topics:

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