PTR3 Hardware and Method
Fig. 1 shows a schematic of the PTR3. The dual stage core sampling inlet permits a virtually contact free injection of analytes. Hence, molecules of low vapor pressures like HOMs (even down to ELVOC) are transported into the PTR3 reaction chamber, almost loss-free and without surface interactions.
Primary reagent ions are generated in the revolutionary TRIONSOURCE. Three separate ion sources enable fast electrical switching between a series of different primary reagent ions (e.g. H3O+ , NO+ , NH4+). Each single ion source uses a corona discharge that ionizes the selected chemical ionization (CI) precursor gas. The corona discharge is followed by a short drift region to purify the selected primary reagent ion. Additionally, all three ion sources are separately pumped to minimize interaction of the CI-gas and the sample. These measures result in ultimatively clean ionization modes with lowest interfering background signals.
The heart of the PTR3 is the patent protected reaction chamber with the enhanced 3D tripole. In conventional PTR-MS technology, the primary reagent ions ionize analytes in a reaction region at low pressure under the influence of an axial DC drift field. Adjusting the reduced electric field strength (E/N) in the reaction region allows to precisely control the ionization energies. In PTR3 however, the 3D tripole is driven by HV-RF voltages creating a rotating field in radial direction that defines the reaction kinetics. Unlike traditional PTR-MS, the axial ion motion is now efficiently decoupled from the electric field. Additionally, the PTR3 is operated at an elevated reaction pressure of 50 to 80 mbar. Since no axial field is present in the reaction region, ions are transported solely by the sample gas flow. This significantly extends the reaction time and subsequently results in outstanding sensitivities while still maintaining IONICON’s patented TRU-E/N ion chemistry.
The 3D tripole ionization chamber is followed by an ION-BOOSTER funnel that effectively focuses the ions into a hexapole ION GUIDE ensuring optimal ion transmission.
Subsequently, the hexapole guides the ions into the lens system of the mass analyzer. The mass analyzer itself is a novel high-resolution ioniTOF 10K, achieving mass resolving powers of typically 10,000 to 12,000 m/Δm.