The most common approach for identifying unknown analytes using mass spectrometry combines fragmentation rules with circular reasoning, working backwards from the answer. But with accurate-mass fragmentation data, you no longer need to work backwards.
See many other examples. Dan's book describes in detail the theory of "partitioning" and how this novel approach has been implemented. This book is available on your local Amazon website: "Mass Spectrometry by the Numbers".
Are you open to a new approach for identifying unknown analytes? If accurate fragmentation data is available in your laboratory, our patented pattern recognition software allows you to visualize your unknown molecule as being composed of underlying small "subfragments" that show how the fragment ions are related to each other. (See the cimetidine example below.) This pattern recognition software, now available as a simple and economical Excel® Add-In, uses the power of mathematics to rapidly transform accurate-mass fragmentation data into a structure-orientated graphical format.
For an overview of how the Excel Add-In can help you to identify unknown analytes, please watch three short youtube videos. These videos are not examples of reference standards where the solution was already known. These are unknown analytes that have been tentatively identified with our Excel Add-In tools. A very simple example is the identification of a fungicide metabolite. The second example describes how an unknown analyte in a surface water sample was identified using our Excel Add-In with substructure searching of the Pubchem database: Subfragments and Substructures. The third video is the tentative identification of the atrazine derivative called "atrazine-deamin".
An authentic sample of chloramphenicol was used to illustrate many of the useful new Excel functions (see Features) that are included with the Excel Add-in and our alternate approach to extracting structural information from accurate-mass fragmentation data: Chloramphenicol Example. This chloramphenicol data is from MassBank Spectrum KOX00157, Institute for Advanced Biosciences, Keio University.
The Excel Add-In also includes mass spectrometric functions such as mass(), RDBE(), IsoCalc(), and Baserate() that are active in any Excel workbook, and hyperlinks to both the CompTox Chemistry Dashboard and Pubchem Compound. Also included is our new high resolution isotope calculator worksheet that plots the isotope distributions in color based on the selected resolution setting. (Isotope Worksheet).