TD-GC-MS
Gas chromatography – mass spectrometry (GC-MS) is the golden standard for the analysis of (semi) volatile organic compounds (VOCs). Our GCMS-QP2010 Ultra (Shimadzu) is equipped with TD-20 thermal desorption unit (Shimadzu). For thermal desorption analysis, VOCs are collected (active or passive sampling) in sorbent tubes containing either a single or multi sorbent bed depending on the range of VOCs of interest.
| Sorbent | Target VOCs |
|---|---|
| Tenax TA | Aromatics, apolars, polar compounds with a boiling point higher than 150oC, and semi-volatiles. |
| Carbograph 5TD | Light hydrocarbons (C3-C6) |
| Carboxen 1000 | Permanent gases and ultra-volatile hydrocarbons |
| Sulficarb | Thiols and very volatile organic compounds |
| Quartz wool | Semi-volatiles |
Since large volumes of air or headspace are collected in a smaller volume, VOCs are pre-concentrated. In the thermal desorption unit, VOCs are released from the sorbent by a flow of a heated inert gas. VOCs are then trapped again on a focussing trap for a second stage preconcentration to maximize sensitivity. In general, VOCs can be detected in the low part-per-billion volume (ppbV) range. Thermal desorption combined with GC-MS allows us to look at complex mixture and obtain confident identifications with the use of mass spectral libraries.
Example of applications for TD-GC-MS
- Breath biomarker discovery
- Environmental VOC analysis