Fittings - HPLC - SIS
Isotope Distribution Calculator and Mass Spec Plotter
This program can calculate the isotopic distribution of
a given chemical species. It can also plot either
calculated or manually inputted isotopic distributions.
This program has been developed by Scientific Instrument
Services as part of the Mass Spec
Tools Collection. For a complete description of this
program visit the
Description of this Program Page. This program is still
under development. If you have any comments or suggestions
we would like to hear from you.
Key in the chemical formula for which you would like to
determine the isotopic distributions. Also type in the
titles and the mass scale range which will be present
in the final graphical output. You have the option of
calculating the masses in low resolution or high resolution.
Example Chemical Formulas:
Calculation should take upwards of a few seconds depending on the
size of the chemical species.
The species is assumed neutral (mass of added/removed electrons and binding energy is not taken into account), which can have an affect on the high resolution methods.
These isotopes are supported:
- Hone (for 1H)
- Htwo (for 2H)
- Hthree (for 3H)
- Ctwelve (for 12C)
- Cthirteen (for 13C)
- Cfourteen (for 14C)
- Nfourteen (for 14N)
- Nfifteen (for 15N)
- 2012-03-26: Molecule size limits have been increased.
- 2012-03-26: Internal changes:
Code has been reimplemented but same algorithms kept.
Speed and memory usage have improved.
- 2012-03-23: Added Ctwelve.
- 2009-10-13: Rounding change: abundances now round to nearest (not round down)
- 2009-10-12: Added support for some labeled isotopes (e.g. Dtwo and Dthree -- see above)
- 2000-02: Low resolution has been enabled again since we have corrected
a roundoff (typically off-by-one) error that was occuring in
low-resolution calculation of certain combinations of larger atoms
(such as Rh). Low resolution now uses the same underlying algorithm as
does high resolution. The "low resolution fast approximation" option
uses basically our previous low-resolution algorithm, except that the
accuracy has been increased by a factor of 10; nevertheless, some
roundoff may occur in large molecules. However, for large molecules,
the fast approximation algorithm is orders of magnitude faster than
the standard algorithm.
Other mass spectra tools
SIS also sells the
Mass Spec Calculator Pro™,
a standalone Windows application. Unlike the online calculator,
you are not as limited to the size of compounds that may be calculated.
A demo may be downloaded.
- Molecular drawing, fragmentation, and autofragmentation
- Enhanced Isotopic Profile utility based on a completely new algorithm that calculates isotopic mass distributions for a structure.
- Elemental Formula utility calculates the possible compositions of an ion given its mass.
- Spectrum Capture utility that can automatically digitize a scanned spectrum and import it for use within MSC.
Isotope distributions can also be calculated using the Isotopes
Calculator in the MS Interpreter tool in the NIST Mass Spectral Database.
Developed by John
J. Manura and David J. Manura,
© 1996-2014 Scientific
Scientific Instrument Services is not
responsible for any errors which may result from the use of this