How to Obtain Elemental Formulae with your Single Quadrupole GC-MS or LC-MS

Tal Alon, Chemistry, Tel Aviv University, Tel Aviv, Israel (polaris@post.tau.ac.il)
                 Afeka College of Engineering, Tel Aviv, Israel (tala@afeka.ac.il)
Aviv Amirav, Chemistry, Tel Aviv University, Tel Aviv, Israel

One of the major strengths of GC-MS sample identification is the ability to perform library search, providing identification results that include names and structures. However, library identification cannot always be trusted and is often not applicable at all as most compounds are not included in the library. Therefore, non-library algorithms that are able to analyze unit resolution EI mass spectra (from GC-MS or LC-MS) and provide elemental formulae, can be very important, especially if they can also help in assessing the validity of the library search results.

We have developed the Tal-Aviv Molecule Identifier (TAMI) software that utilizes several algorithms which improve the measured mass accuracy and invert the mass, together with the molecular ion's isotopomeric pattern, into elemental formulae. TAMI automatically supports or rejects library identification results, and in a case of rejection can quickly provide the compound's elemental formula. 

For every independent analysis, TAMI provides a table of elemental formulae with declining order of matching to the experimental data, and presents additional statistical information. TAMI also includes a unique smart-analysis assistant that provides help in more complex cases, making sure the analysis conditions are optimal.

TAMI Improves the mass accuracy of quadrupole mass analyzers to <100 ppm (typically 40 ppm), and in combination with isotope abundance analysis upgrades these unit resolution mass spectrometers to be similar in sample identification capability to costly accurate mass GC-TOF-MS with 1 ppm mass accuracy. 

TAMI is compatible with several data analysis software such as Agilent's Chemstation and MassHunter, Thermo's XCalibur and Chromeleon, and can analyze both profile and standard centroid data files. TAMI can also analyze single quadrupole LC-MS data files such as Advion’s CMS with its Data Express software.

You are invited to bring your files for a demonstration analysis. A demonstration video of TAMI’s operation can be found at:

https://www.youtube.com/watch?v=Pj37XCd-7b8.