Application Note

Toluene-Assisted APCI and Elemental Composition Prediction Using a Compact Mass Spectrometer


  • Toluene-assisted APCI (TAPCI) can generate (M) and (M+H)+ ions from analytes that cannot be ionized by ESI or APCI.
  • Elemental formula prediction at 250 ppm accuracy and isotope distribution matching by TAMI (Tal Aviv Molecule Identifier) supports analyte identification.
  • Combining both TAPCI and TAMI on the expression compact mass spectrometer (CMS) provides a cost-effective analysis platform for a wide range of compounds.


Many compounds in organic synthetic chemistry either have no functional group, a C=O carbonyl group, or protected functional groups and are difficult to ionize by ESI or APCI for detection by mass spectrometry. TAPCI has been shown to ionize compounds to (M) and (M+H)+ protonated molecules not accessible by ESI or APCI MS analysis. The ionization is believed to include a charge transfer reaction in the APCI plasma region of the source. Elemental formula prediction using TAMI allows analyte identification on a single quadrupole mass spectrometer with mass accuracy in the 250 ppm range, isotope pattern analysis and auto comparison to NIST databases. Here, we investigate the use of both techniques on the expression CMS as an attractive and cost-effective solution
for analyte identification covering an increased compound space.