An Isotopic Pattern Generator or Isotopic Pattern Calculator generates isotopic abundance peaks for molecular formulae.
There is an evolution of isotopic pattern generators in terms of accuracy and speed during the years. There are several implementations in commercial products and on web resources. Many of them produce different isotopic abundances for higher mass ranges. If the method for calculation is not mentioned, these calculators should be handled with caution. The isotopic distributions are dependent on the effective resolution. If the selected resolving power is very high (> 100,000 FWHM) the peaks become very sharp and the isotopic fine structure is detected. Be advised that high resolving power alone is not sufficient for unique formula assignment, even if isotopic patterns are used. You would need a resolving power of 10,000,000 (FWHM) over a scan range of 0u to 2000u to resolve most species in complex matrices.
C42H30N6O12 at R= 1000 @ 500 m/z
C42H30N6O12 at R= 10,000 @ 500 m/z
C42H30N6O12 at R= 1,000,000 @ 500 m/z
A typical text output (MWTWIN) looks like this:
| Isotopic Abundances for C42H30N6O12 | ||
| Mass/Charge | Fraction | Intensity |
| 810.19216 | 0.6019153 | 100.00 |
| 811.19216 | 0.2922263 | 48.55 |
| 812.19216 | 0.0842879 | 14.00 |
| 813.19216 | 0.0179672 | 2.99 |
| 814.19216 | 0.0031021 | 0.52 |
| 815.19216 | 0.0004551 | 0.08 |
| 816.19216 | 0.0000635 | 0.01 |
| 817.19216 | 0.0000066 | 0.00 |
Additional Download Links
Download free Isotopic Pattern Generator or or programs for calculation of isotopic fine structures:
- A free Mercury implementation in Decon2Ls from PNNL
- A free implementation within MWTWIN from Matthew Monroe (PNNL)
- A semi-free implementation IsoPro from Mike Senko
- A free high speed version emass and qmass from Pentti Somerharju and Perttu Haimi
- A free memory efficient algorithm IsotopeCalculator (for elements CHNOS only) from Pengyu Hong
- A free Mercury implementation libmercury++ from Marc Kirchner ( Rockwood's Mercury7 algorithm)
- A free original Mercury implementation can be obtained from Alan Rockwood (ArupLab, BHY.edu)
- A commercial and very flexible version implemented in Thermo XCalibur (comes with every LTQ)
- A free version of IsoPatrn, ISOMABS from TARC Dalhouse University
- A free version of DEUTERIUM from Jorge Cossio [PDF1] and [PDF2]
Reference tables for accurate mass and accurate isotopic abundances
ATOMIC WEIGHTS OF THE ELEMENTS: REVIEW 2000 - (IUPAC Technical Report)
Pure Appl. Chem., Vol. 75, No. 6, pp. 683–800, 2003.
J. R. DE LAETER, J. K. BÖHLKE2, P. DE BIÈVRE, H. HIDAKA, H. S. PEISER, K. J. R. ROSMAN, AND P. D. P. TAYLOR