Peptide Ion Calculator

Peptide Ion Calculator is the perfect tool for peptide and protein chemists

Peptide Ion Calculator makes analyzing mass spec data of peptides a breeze. Build you peptide's sequence, then enter experimentally observed ions. Peptide Ion Calculator will return any potential ion who's theoretical exact mass is within 0.3 amu of your observed mass.

Amino Acids:
All 20 natural amino acids
Several unnatural amino acids
Several N-methylated amino acids
One N15 labeled amino acid

Now introducing custom masses! Cant find an amino acid or side chain modification? Add it to the app yourself!

Peptide Ion Calculator makes it easy to troubleshoot a failed synthesis. Peptide Ion Calculator will search your observed mass against a list of singe and double deletions/additions, as well as a number of side reaction that can occur during solid phase peptide synthesis.

Side Reactions:
Guanidinylation of amines
Incomplete deprotection of Fmoc, Boc, Trityl, tBu, Acm.

Currently supports positive ionization mode, up to triply charged species, either as M or 2M species:
plus H, Na, or K.