MassQC Help > Metrics > Ion Source          
The Metrics that Describe the Ion Source:

An unusual number of any of the +1, +3, +4 ions may indicate problems with the electrospray source. Also they may indicate the instrument needs to be returned, as it may not be set up to ideally detect peptides.

An excess of very short peptides or very long peptides can be detected by looking at the overall precursor m/z.

  • Percent +1H is the percentage of all spectra that have ions with a charge of +1.
  • Percent +3H is the percentage of all spectra that have ions with a charge of +3.
  • Percent +4H is the percentage of all spectra that have ions with a charge of +4.
  • Spray Instability measures how often the ion current jumps or falls by more than 10 times between adjacent scans.
  • Precursor m/z is a measure of the mass/charge for the precursor ions seen in MS1.
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