ACE 1100 Ion-Molecule Reaction Mass Spectrometer(IMR-MS) is an optimized mass spectrometer for qualitative and quantitative analysis of Volatile Organic Compounds(VOCs). GC-MS and LC-MS use chromatography system(GC, HPLC) for separation of analysis compounds and need the interface between mass spectrometer and chromatography system. In contrast with GC-MS & LC-MS, IMR-MS loads sample directly into the mass spectrometer and immediately can get analysis results in real-time. It can be used not only in the laboratory, but also on-site analysis is required, the place where the on-line monitoring is necessary.
Analysis process of IMR-MS follows reagent ion(precursor ion) production → precursor ion selection → Ionization of analytes(precursor ion react with analytes) → qualification & quantitation procedure
Soft Chemical Ionization
The ionization step of analytes is an essential procedure when you use a mass spectrometer for analysis of sample compounds, and typical ionization methods in mass spectrometry are Electron Impact Ionization(EI) method and Chemical Ionization(CI) method. IMR-MS uses a soft chemical ionization method, and it ionizes the sample molecule itself or minimizes the fragmentation of the target molecule. By this ionization method, you can get a simple and accurate mass spectrum.
※ Chemical Ionization Mechanism
· Proton transfer : Proton affinity of sample molecule > Proton affinity of precursor an ion
M + H+ → MH+ (CH₃)₂CO + H₃O+ → (CH₃)₂COH+ + H₂O
· Electron transfer : Ionization energy of sample molecule > Ionization energy of precursor ion
M → M+ + e O₂+ + C6H6 → C6H6+ + O₂
· Dissociative Electron transfer : The ionization potential of the sample molecule is lower than 12.07 eV and 9.26 eV, O₂+ and NO+ can react electron transfer mechanism.
AB → A+ + B + e- O₂+ + n-C₄H10 → C₃H7+ + O₂ + CH₃
· Hydride abstraction : A hydride ion is transferred from the molecule to the reagent ion, NO+ or O₂+ abstract hydride.
NO+ + CH₃CHO → CH₃CO+ + NOH
· Association : Molecular association by the collision with carrier gas ion.
A+ + M → AM NO+ + CH₃OH + He → NO. CH₃OH+ + He
These are ion sources for chemical ionization of sample molecules. Microwave plasma produces some ions such as H₃O+, NO+, O₂+ using normal water(H₂O), and air(N₂, O₂). These reagent ions pass through 1st mass filter and according to analysis condition, a specific ion or three ions move to the reaction chamber for the next step.
Ionization of Analytes
The reagent ion(or ions) moves to the reaction chamber react with a loaded sample molecule in this chamber to produce molecular ions. In this ionization process, different kinds of reaction mechanisms are applied such as Proton transfer, Electron transfer, dissociative Electron transfer, Hydride abstraction, Association. By these different ionization mechanisms, each reagent ion produces specific molecular ions which will help to identify the compound.
Quantitation & Qualification
Molecular ions are separated and selected according to their mass-to-charge ratio in the second mass filter and are converted into an amplified electric current in the detector(Electron multiplier).
ACE 1100 touchpad controller setup and manage each part of the system (microwave plasma, reagent ion selection, sample loading port, reaction chamber, molecular ion selection, detector, and vacuum pump). Independent operation with 10.1” touchpad controller provides on-site operation and operation mounted in a vehicle.
ACECube is a program for external PC to process analysis data. It makes the system easy to operate from the method set up to data analysis. Built-in SW : 10.1” TFT color LCD, Embedded Linux base program support reinforced security / System control and data monitoring ACECube software : analysis method setup, analysis data processing, Real-time data acquisition, library matching, identification.
· Environmental air & water contaminants – Volatile Organic Compounds · Indoor air quality(sick building syndrome) – Formaldehydes · Odor – Sulfur compounds(mercaptans, thioethers) · Automotive interior – Formaldehyde, VOCs · Occupational safety – Residual fumigant · Semiconductor facility – Airborne Molecular Contaminants · POCT – Marker for infectious disease