New Qualitative Analysis Capabilities offered by a Variety of Soft Ionizations
AccuTOF™ GC-Alpha provides multiple ionization methods
Soft ionization - a powerful tool for qualitative analysis
EI, the most widely used ionization technique in GC-MS, is superior in sensitivity and reproducibility and is supported by a variety of library searchable databases.
For any scientist using GC-MS in search of further information, what is ultimately important is molecular ion detection. EI, which uses a high ionization energy of 70 eV, generates numerous fragment ions, from which structural information is acquired. However, EI often fails to show strong molecular ion signals. Consequently, qualitative analysis results may be incorrect if they solely rely on database searches.
Thus, it is critical in GC-MS analysis to enhance the accuracy of qualitative analysis by using various soft ionization techniques in addition to EI. Chemical ionization (CI), photoionization (PI), and field ionization (FI) are all optionally available on the AccuTOF™ GC-Alpha. With the accurate mass measurement capability for all ionization techniques, elemental composition of the analyte can be reliably determined.
FI and FD ~ Ideal Soft Ionization Techniques for Molecular Weight Determination
FI and FD are extremely soft ionization techniques that provide lower internal energy to the analytes than EI and even CI, thus producing clear molecular ions.
As a result, FI and FD are ideal for molecular weight determination.
FI (Field Ionization)
- The sample is introduced to the ion source through GC or a standard sample inlet system.
- Unlike CI, FI uses no reagent gas; no need to choose a reagent gas appropriate for the analyte.
FD (Field Desorption)
- The sample is applied onto the emitter and directly introduced into the system.
- Suitable for analysis of thermally labile compounds.
- Ideal for samples soluble in nonpolar solvents.
- Analyzes powder samples dispersible in solvents.
- Analyzes low- to mid-polar metal complexes.
- Analyzes high molecular weight samples not supported in GC-MS, such as polymers.
In FI and FD, ionization occurs by the removal of electrons from neutrals via the action of a high electric field.
FI and FD ~ EI/FI/FD Combination Ion Source (optional)
A single ion source that supports both EI (hard ionization) and FI/FD (soft ionization) techniques.
Switching between EI and FI/FD is simple and quick.
Features
- No need to replace the ion source
- No need to break the vacuum
- No need for reagent gases
The following analyses are possible by using this combination ion source with GC:
- GC/EI for qualitative analysis through library search
- GC/FI for molecular weight determination
- Accurate mass measurement
PI (Photoionization) ~ EI/PI Combination Ion Source (optional)
PI is an ionization method that uses photons from a vacuum ultraviolet (VUV) lamp for ionization. The AccuTOF™ GC-Alpha has an optionally available combination ion source that offers both EI (hard ionization) and PI (soft ionization). This source makes it possible to switch between EI and PI by simply turning on/off the EI filament as well as the PI lamp.
Features
- No need to replace the ion source
- No need to break the vacuum
- No need for reagent gases
Schematics of EI/PI Combination Ion Source
PI is particularly useful for the analysis of aromatic compounds in complex mixtures. These compounds produce high intensity peaks with PI because they strongly absorb UV light.
A new generation of analysis software for simple, speedy operation
Key Technology 2
A new workflow has been devised to identify unknown compounds by GC-MS. In this workflow, the data analysis is performed by integrating the data obtained by hard ionization (EI) and the data obtained by soft ionization (FI, PI, CI) in order to identify the analytes present in a sample.
Since its introduction in 2018, the msFineAnalysis software for the AccuTOF™ GC series has been well received as an innovative software solution for the automatic qualitative analysis of unknown compounds.
This software makes full use of the high-quality data obtained by the AccuTOF™ GC-Alpha, thus providing a new approach to qualitative analysis for identification of unknown compounds.
Evolution into Version 3
Version 3 of msFineAnalysis streamlines the software operation and adds a new function in which 2 similar samples can be directly compared for differential analysis. This new, enhanced version of msFineAnalysis allows the operator to easily accomplish qualitative analysis of unknown compounds as well as for compounds that are unregistered in the EI mass spectral libraries.
Features of msFineAnalysis
- Combines EI/SI data for automatic qualitative analysis
- Chromatographic peak deconvolution
- Group analysis for extracting compounds with common substructures
- Differential analysis for directly comparing 2 samples
- Also supports the analysis of EI data alone
msFineAnalysis provides quick and efficient data analysis so that the user can spend less time analyzing data and more time on research and creativity!
AccuTOF™ GC-Alpha with Direct MS
Direct MS mode is useful for the analysis of high-boiling-point and high-mass compounds that are not amenable for GC.
TOFMS with inherent wide mass range is well-matched with direct MS mode.
Compounds that are measured by GC normally have molecular weights below 500 Da so it is not common to target compounds with molecular weights exceeding 1000 Da by using GC-MS. However, in direct MS mode (no GC is used), high-boiling-point, high-molecular-weight, and nonvolatile compounds can be targeted for measurement, as the sample is directly introduced into the ion source. The mass range of the AccuTOF™ GC-Alpha is m/z 6,000 or higher. Since compounds can be detected over a wider mass range than conventional GC-MS, the system is well suited for measurements in direct MS mode.
Three Direct MS Probes To Choose From
Polymer analysis by FD and Kendrick Mass Defect (KMD) Analysis
FD is an ionization method in which the analyte molecules applied to the emitter are desorbed and ionized by a high electric field. The electric current running through the emitter is gradually increased during the measurement to heat the analyte to assist desorption/ionization. Since the optimum emitter current for ionization depends on the analyte, components can desorb at different times. Separation of components in a mixture is possible, and mass spectra for a specific class of compounds can be extracted. Furthermore, even when compounds are not separated in time during desorption/ionization, each other, target components can still be clearly separated by creating KMD plots.