MS Peak Comparison

The following two text areas please use to drop sets of MS peaks that you desire to compare. The tool will inform you on the peaks that are found on both sets and on those that are found in either. It will also tell you the difference in mass to the peak closest to either set.

A common scenario to use this tool is to present your measurements on the left side, while theoretical masses (e.g. from MS-Digest@UCSF or MS-Product@UCSF) are copied to the right side. Another scenario is that two measurements are compared.

To cite this tool please refer to this URL, authors are Steffen Möller, Michael Kreutzer and Michael O. Glocker.

Only submitting left side
Only interpret first number per row, i.e. ignore intensities
Select on subsets of modifications to be analysed:
Molecular weight (rounded integers) of common post-translational modifications
Weight of amino-acids
Weight of substitution of single amino acids
Weight of substitutions of pairs of amino acids
Custom PTMs:
Max Delta for Identity [Dalton]:
Name of Left:
Name of Right:
Ignore the following peaks:
Show common peaks
Show unique peaks
Show distribution of distances

For comments please mail to Steffen Möller ( or Michael Kreutzer ( PHP Source code (<350 lines) is available on request.
Ideas for enhancements are:

  • Link to MASCOT from unique/common sets or any subset of peaks selected (Möller)
  • annotate differences (not only of the nearest neighbour) with known PTMs (Glocker, Madi - Implemented)
  • count number of occurrences of arbitrary distances (Madi - Implemented, rounded on int)
  • conditional presentation of unique and common peaks, submission of custom PTMs (Carolyn L. Crankshaw - implemented)