Article

Exploring the Power of TOF-SIMS by Coupling Collision-Induced Dissociation and Surface-Induced Dissociation

Surface Analysis Spotlight: TOF-SIMS

by Jacob Schmidt Staff Scientist

Mass spectrometry (MS) is a widely used technique for atomic and molecular analysis that measures the mass of charged particles based on fundamental properties such as an ion’s resonant frequency or its velocity. Tandem MS builds on this by isolating ions of interest, fragmenting them into their component parts, and conducting additional MS measurements on the fragment ions to determine the precursor ion’s molecular structure.

Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) is a specialized mass spectrometry technique that analyzes the surface composition of a solid sample rather than bulk or solution phase samples. However, identifying large molecules with TOF-SIMS presents challenges due to the increasing number of possible formulae at large masses. Tandem MS provides a solution to this challenge by identifying the functional groups of large molecules in order to accurately reconstruct the molecular structure. In the example below, tandem MS was used to identify the structure of a biosynthetic precursor responsible for the anti-fungal properties of Sextonia Rubra wood oil¹.

Determining when to use tandem MS and how to effectively interpret the fragmentation spectrum can be a daunting task. This presentation will introduce the application of tandem MS in PHI’s nanoTOF spectrometer, explore examples of how it can be used to address complex problems, and showcase the power of tandem MS coupled with the surface sensitivity of TOF-SIMS. Additionally, we will discuss the concept of surface-induced dissociation (SID) and how it can provide complementary information compared to traditional collision-induced dissociation (CID).

To learn more about using tandem MS in your TOF-SIMS analysis, please attend the upcoming talk, “Exploring the Power of TOF-SIMS by Coupling Collision-Induced Dissociation with Surface-Induced Dissociation for Structural Analysis", by Dr. Jacob Schmidt at AVS 70 in Tampa, Florida

Figure 1 - Tandem MS fragmentation spectrum and structural analysis of Rubr(e/y)nolide, showing how the identification of functional groups in a tandem MS spectrum can be used to determine the precursor ion’s structure. Chemical formulae above the arrows indicate a “neutral loss” fragment from their respective precursor ion and point to the observed ionized fragment.

1. T. Fu, et al, Nat. Sci. Rep. 9 (2019) 1928-1938; T. Fu, et al, Anal Chem. 90 (2018) 7535-7543.