...the ITEX mode

Thermal desorption offers a cost-saving and high sensitivity alternative to conventional sample preparation methods for the analysis of trace level organic chemicals. The technology combines efficient sample extraction, with selective analyte concentration and rapid transfer of target compounds to the GC, GC-MS system or other vapour-phase analysers like e.g. Enose sensors.

CTC Analytics' aim is to supply instruments to customers which make the operation of sample processing simple and transparent. In-line with todays lab requirements for productivity, CTC expanded the application range of it's GC Injector System CombiPAL introducing the ITEX Option. The ITEX Option consists of an add-on module which can be used with any existing or new CombiPAL System. It performs enrichment of volatile or semi-volatile compounds during headspace analysis. A microtrap filled with adsorbent material, such as Tenax or activated charcoal is placed between the CombiPAL Headspace syringe and the syringe needle. Using the HS syringe as a pump, a part of the gaseous phase of the sample vial is pumped repeatedly through the microtrap. This system setup allows rapid, simple and efficient extraction of volatile and semi-volatile sample compounds. To gain sensitivity simply the number of pumping strokes can be increased or several different vials containing the same sample can be extracted. During thermal desorption into the GC Injector the microtrap is rapidly flash heated and compounds reach the GC column as a narrow band. No cryofocussing is needed to obtain sharp peaks. For applications containing extreme volatile compounds the GC carrier gas may be temporarly shut down to avoid peak broadening.

Enrichment of Methylesters on a Tenax TA ITEX trap.

1µl of a mixture of C4, C6, C8, C10 Methylesters in Methanol (100ng / µl) was injected into a 20ml HS-vial. After conditioning at 40°C for 10min. 1ml of the headspace using a ITEX trap without packing material was injected to determine a "static headspace value" (0x). Afterwards the needle was replaced by the TENAX TA ITEX trap. The enrichment of the solutes on the trap was studied using various numbers of pumping strokes.