Selective Reagent Ions Upgrade
Selective Reagent Ionization (SRI): Advantages of using NO⁺, O₂⁺ (or Xe⁺), NH₄⁺, and H₃O⁺ as reagent ions
H3O+ is ideal for many applications as our customers have proven for more than a decade. In some cases however it can be useful to use more than one reagent ion in your PTR-MS.
With the SRI-MS technology several isomeric VOC compounds can be separated and instantaneously quantified (the differentiation of isobaric compounds is already possible by using PTR-TOFMS series). Like H3O+, NO+ is a soft ionizer; however, its ionization occurs mainly through charge transfer. O2+(or Xe+) is found to be a less soft chemical ionization agent and can be used where proton transfer from H3O+ does not work.
NH4+ reagent ions are particularly beneficial in complex mass spectra because of higher sensitivity (less fragmentation) and higher selectivity (higher proton affinity). We developed a unique method for fast switching to/from NH4+ reagent ions without adding ammonia (US Pat 11,342,171, EP 3503161 B1, CN 111,386,590 B).
Selective Reagent Ionization PLUS (SRI⁺) feature: with Kr⁺ as reagent ion
Another revolutionary development is the implementation of Kr+ as reagent ion, made available as the optional SRI+ feature for IONICON PTR-MS instruments (US Pat. 9,188,564, EP 2606505 B1).
The Kr⁺ reagent ion can ionize substances with higher ionization energies than O₂⁺ and therefore also very important substances (including inorganics) such as CH4, CO, CO2, NO2, SO2, etc. can be detected and quantified using a single IONICON instrument.
Learn more about Selective Reagent Ionization - Mass Spectrometry (SRI/SRI+) and download the brochure:
Selective Reagent Ionization for PTR-MS
