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  The Rational Numbers™ Excel® Add-In

1. De novo generation of modular structures allows chemists to work forward from their fragmentation data - before hypothesizing structures of unknowns. You no longer have to work backwards from a proposed structure, where the proposed fragment assignments are based on a proposed structure that may be incorrect; this older approach is a classic example of circular reasoning.

2. Simple to use. Data interpretation no longer has to be the bottleneck. With this Excel Add-In, data interpretation can be decentralized because chemists with a strong background in organic chemistry and familiarity with Excel can interpret their own data.

3. Key mass spectral functions are included. Like all of the functions that come standard with Excel, these new mass spectrometry functions fill down and across and automatically update cells for changes.

Mass() calculates the exact mass of a given elemental formula. For example, typing =Mass("C5H11NO2S"), the formula for methionine, into a cell will return the exact mass of the monoisotopic mass of methionine. If the formula C5H11NO2S were present in CellD37, then typing =Mass(D37) into a different cell would return the monoisotopic mass of that formula which is 149.0511. For convenience, there are some special masses available such as the mass of a proton, Mass("proton"), and deuterium, symbol D.

RDBE() calculates the the total number of rings and double bond equivalents in a given elemental formula or any combination of atoms.

ET() The extraterrestial function determines whether a given accurate-mass or accurate-mass difference is possible. It assumes that the mass spectral data is accurate to within 5 mDa. A value of true indicates that the given mass is extremely unlikely.

BaseRate() The BaseRate function returns the relative base rate frequency (on a scale of 0 to 99) at which a given heavy atom combination was found in 230000 common molecules. This function is limited to formulas that have a mass less than or equal to 250 daltons.

IsoCalc() The IsoCalc function returns the estimated relative isotope intensities (on a scale of 0 to 100) for a given elemental formula or any combination of atoms. This function outputs low resolution isotope patterns.

4. For checking high resolution isotope data, a separate Isotope Worksheet can be used to generate isotope patterns that are color-coded to display the different combinations of elements that comprise the individual isotopologues. The resolution of the display is selected by the user.

5. Hyperlinks to two databases are built in.

Hyperlink(Pubchem(cell),cell) The Hyperlink(Pubchem(cell),cell) function creates a hyperlink to the Pubchem Compound database that can be used to initiate a search of any subfragment formula or molecular formula found in a designated cell.

Hyperlink(EPA(cell),cell) The Hyperlink(EPA(cell),cell) function creates a hyperlink to the EPA CompTox Chemicals Dashboard that can be used to initiate a search of any subfragment mass or molecular mass found in a designated cell.

6. Input by typing, cut-and-paste, Excel's Get Data, or with our optional SPS software that can quickly process entire chromatograms.


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