SOFTWARE FOR MASS SPECTROMETRY
Members of the Trace Analysis Research Centre have written computer programs that do a variety of calculations helpful for mass spectrometrists. These include the calculation of isotope cluster patterns for simple and tandem mass spectra, accurate masses of noncovalently bonded cluster ions, atom enrichment levels, and all formulae of ions with a specific mass-to-charge ratio. These can be downloaded gratis as explained below.
Isotope Cluster Patterns
IsoPatrn is a program that calculates the isotope cluster pattern of an ion in simple or tandem mass spectra (MSn for n up to 4). The ion may contain any of the atoms in the Periodic Table with stable isotopes. Six user-defined elements may also be introduced. Calculation of isotope patterns for product ion, precursor ion, or neutral loss mass spectra is supported.
The code, written for Windows-based personal computers in Microsoft Visual C++, employs the "classical" polynomial expansion algorithm and uses 80-bit floating point math routines to improve accuracy for very large molecules. IsoPatrn requires a 32-bit or a 64-bit operating system, Windows 98 or later or Windows NT V4.0. There are no large memory or disk space requirements.
IsoPatrn provides regular Windows features including HTML-style help, hard-copy output, and the ability to save the results to simple text files, the data in which are comma-delimited for ease of importing into spreadsheet programs. The most recent edition of IsoPatrn is Version 2.12. This version contains several features not included in previous editions. These include the ability to list the individual components that make up eack peak in the isotope cluster and the ability to plot the resulting cluster spectrum at a resolution chosen by the user. The individual peak components can be saved to a file as well as the data used to generate the graph. IsoPatrn V2.00 could print the actual spectrum, but it could not save the spectrum in a graphical format. The latest version has the ability to export the spectrum in graphical format as an enhanced metafile, which can be imported easily and directly into word processor, spreadsheet, and presentation applications. It also supports the listing of individual components in product ion spectra with up to four stages of mass analysis (MS4).
IsoPatrn is provided in compressed or "zipped" form in a package of 465 kB. Download IsoPatrn.
Accurate Mass, Formula, Enrichment Calculations
The ISOMABS6 program will calculate ISOtopic Masses and ABundanceS found in mass spectral isotope patterns, as well as give possible formulae and classify ions as even- or odd-electron for a given m/z value.
Essentially all compounds containing elements with two or more natural or user-enriched isotopes exhibit mass spectra having isotope cluster ions. Most of the ISOMABS6 Program is designed to assist with understanding and dealing with the features arising from these clusters of ions.
The suite of programs will allow for:
- calculation of isotope cluster patterns in single-stage MS from naturally-occurring species,
- calculation of isotope patterns from ions having user-specified isotopic enrichment,
- calculation of isotopic enrichment levels from the experimental mass spectrum of a compound enriched in a specific element,
- calculation of accurate mass-to-charge ratios and isotope patterns of noncovalently bonded cluster ions,
- calculation of all possible formulae for ions within a specific range of m/z ratios, which can be very helpful in interpreting fragmentation patterns in a mass spectrum,
- correction of experimental peak intensities for ions having intense [A-1] ions,
- display current isotopic data for any of the 84 stable elements.
The code, written for Windows-based personal computers, has been completely revised from the original DOS version using Microsoft Visual C++. ISOMABS6 requires a 32-bit or a 64-bit operating system, Windows 98 or later, or Windows NT V4.0. There are no large memory or disk space requirements. The new version provides regular Windows features including HTML-style help, hard-copy output, and the ability to save the results to simple text files, the data in which are comma-delimited for ease of importing into spreadsheet programs.
Other changes/improvements to ISOMABS include: (1) the ability to include all of the 84 stable elements in almost any of the calculations, (2) increasing the number of user-defined elements to six for most of the calculations, (3) the use of conventional chemical formula entry, and (4) the ability to estimate the enrichment of all the isotopes of elements with up to four isotopes.
The most recent edition of ISOMABS6 is Version 6.0. It is provided in compressed or "zipped" form in a package of 430 kB. Download ISOMABS6.