Description
Thermo desorption two-dimensional quadrupole-time-of-flight mass spectrometry (TD-GCxGC-QTOF-MS) is used for accurate analysis of highly-complex volatile mixtures in ultra-low concentrations and/or of un-known identity. This instrument is part of the headspace facility. The other part of this facility is the high-throughput headspace sampling facility.
Principle
A Markes thermal desorber TDU that can hold up to 100 cartridges containing Tenax or other absorbents is installed on an Agilent 7890 gas chromatograph coupled to an Agilent QTOF Mass Spectrometer. Thermal desorption is a prerequisite for highest sensitivity in headspace analysis. The GC is equipped with a Zoex GCxGC modulator that allows superior separation of complex volatile mixtures on two different GC-columns for ultra-high separation power (comprehensive 2-dimensional GC). A bypass allows routine analysis to be done on a single GC-column. A second PTV allows the possibility for liquid injection, bypassing the TDU. The accurate mass QTOF Mass Spectrometer will give full spectrum acquisition with high sensitivity and high resolution mass spectra that result in unsurpassed identification possibilities. For off-line adsorbent-cartridge conditioning a Sim Tube conditioner can be used
Technical Details
GC/Q-TOF (Agilent) Performance Specifications
- Resolving Power: > 12.5K at m/z 272; 13K to 15K typical
- Mass Accuracy: < 5 ppm at m/z 272; < 2 ppm typical
- MS Sensitivity >400:1 at m/z=272
- MS/MS Sensitivity is between SRM and Product Ion scan of a Tandem Quad MS
- Dynamic Range: 3-5 orders of magnitude
- Quad Mass range: 20-1050 Da (0.7-4.0 Da FWHM)
- TOF Mass range: 20-1700 Da
- Spectral Rate: 1-50 Spectra/sec
Zoex modulator for GCxGC
- 2 stage loop modulator
- Closed cycle cooling assembly for cold jet
- Modulation cycle range from 1000ms – 32000ms
Thermodesorbtion: Unity/Ultra (Markes)
- automated thermal desorption system for the rapid and unattended processing of up to 100 sample sorbent tubes in a single sequence
- electronic control of split and desorb flows
- quantitative sample re-collection
- Sim tube conditioner with capacity for 20 tubes, temperature programmable max 400°C
Applications
- Identification of volatiles produced by plants attacked by herbivores and identification of all compounds involved
- Detection of pathogens and insects in greenhouses using the induced volatiles as indicators for the type of biotic stress as well as its severity
- Quality of vegetables and fruits during ripening (e.g. tomato storage)
- Identification of human skin volatiles important in host finding by malaria mosquitoes
- Finding volatile biomarkers for disease diagnosis using breath analysis
- Disease detection in animal husbandry
- Chemical characterization/identification using the accurate mass option after GC analysis for volatile identification and obtaining accurate masses of non-polar molecules for compound identification or confirmation.