Isotope Pattern
The distribution of molecular masses that the natural isotopic composition of the elements produces — the M, M+1, M+2 series a mass spectrum shows — together with the monoisotopic and average mass.
- You supply
- A chemical formula, in the same grammar every other page here uses. Whole atoms only: a pattern describes one molecule, so a fractional stoichiometry is refused rather than rounded. Write a charge into the formula (
SO4^2-,Na+) and every mass becomes m/z, electron mass included. - Reading it
- Abundances are relative to the tallest peak, which is not always the monoisotopic one — for tin or a polybrominated compound it is not. This is an exact combinatorial result, not a simulated spectrum: no resolution, no peak shape, no adducts and no fragmentation.
Worked examples: a nickel complex · dibromomethane · tin tetrachloride · a sulfate anion
Input
Results
| formula: | C32H26N2O2Ni |
|---|---|
| monoisotopic mass: | 528.13477 |
| average mass: | 529.2556 |
| base peak: | 528.1348 |
Pattern
| mass | nucleons | relative / % | abundance |
|---|---|---|---|
| 528.1348 | 528 | 100.00 | 47.524 % |
| 529.1380 | 529 | 35.72 | 16.974 % |
| 530.1318 | 530 | 45.12 | 21.443 % |
| 531.1337 | 531 | 16.27 | 7.733 % |
| 532.1310 | 532 | 8.56 | 4.069 % |
| 533.1325 | 533 | 2.35 | 1.116 % |
| 534.1291 | 534 | 1.76 | 0.836 % |
These are the relative abundances that follow from the natural isotopic composition of the elements — an exact combinatorial result, not a simulated spectrum. There is no instrument here: no resolution, no peak shape, no adducts and no fragmentation. Combinations with the same number of nucleons are shown as one peak at their abundance-weighted mass, which is what an instrument of ordinary resolving power sees; at high resolution several of these would split. Abundances are relative to the tallest peak, which is not always the monoisotopic one.