Tenax trap

Figure 14.12 Schematic diagram of the Refomiulyser system Inj, split injector Cl, polar capillary column C2, packed column to retain the alcohols C3, packed Porapak column for the separation of the oxygenates C4, non-polar capillary column C5, packed 13X column A/E cap, Tenax trap to retain the ar omatics Olf. trap, cap to retain the olefins Pt, olefins hydrogenatOT A cap, cap to retain the -alkanes FID, flame-ionization detector.

Breath Collection using a spirometer adsorption on Tenax traps thermal desorption cap GC/MS No data No data Barkley et al. 1980... 

Ambient air samples are collected on adsorbents such as Tenax (Wallace 1987), or multisorbent (Heavner et al. 1992 Oliver et al. 1996), or in passivated canisters (EPA 1988a). Tenax traps are thermally desorbed, concentrated cryogenically, and analyzed by capillary GC/MS (Wallace et al. 1987). Recovery is good (81-110%), precision for side-by-side samples is acceptable (9-45% RSD), and the detection limit is 1 g/m (Wallace 1987). Multisorbent traps may be solvent desorbed and analyzed by capillary GC/MS. Recovery and precision are good and detection limits as low as 0.019 ppb have been reported (Oliver et al. 1996). Collection of air samples in passivated stainless steel canisters is also widely utilized (EPA 1988a), but performance data are unavailable. Passive sampling devices are also widely used, due in part to their ease of use and small size (Lewis et al. 1985). 

Fig. 15.18 Unambiguous identification of the molecules assigned to the trace ions. This identification is only valid for the first 120-s period of Tenax trapping. (Adapted from [199])...

Data Reduction. A gas chromatographic profile of the Tenax-trapped volatiles from a 33.3% bright/33.3% burley/33.3% oriental tobacco sample is shown in Figure 6. The 22 selected peaks are designated. 

Figure 5. Apparatus used for the dynamic headspace extraction of solid foods. (1) Carrier gas (He) inlet, (2) belt transmission, (3) glass cylinder (99 x 8.5 cm), (4) Tenax trap (16 x 1.8 cm), (5) thermostat [adapted from reference 55],...

A typical total ion current chromatogram of the Tenax trapped canned black truffle (Tuber Melanosporum) juice volatiles is shown in Figure 2. The compounds identified by GC-MS are listed in Table I in the order of elution from the GC column with their characteristic mass spectral data. The identification of these compounds was based on comparison of the mass spectra obtained with those stored in the NIH/EPA library and also with those of authentic compounds. Moreover, an additional search of published standard mass spectra to confirm the identity of unknowns was undertaken (16). 

The volatile compounds in the atmosphere of cold stored Black Perigord Truffles (Tuber Melanosporum) were adsorbed onto a Tenax trap by means of a vacuum pump. The efficiency of the sampling method was sensorially validated. The volatiles eluted from the trap by heat desorption were analysed by capillary gas chromatography - mass spectrometry. A total of 26 compounds was identified. Their contribution to the final aroma impression was discussed. 

One of the auxiliary Tenax tubes (1) was placed inside the desorption oven (2), located upstream of the fixed Tenax trap (3) (0,2 g Tenax GC, 60-80 mesh, packed into a 7 cm by 2 mm i.d. stainless steel tube). At controlled temperature (lOO C) and low pressure (1,5 psl) the oven was flushed by a 25 mL/min flow of Helium for 10 min. Desorbed and diluted in scavenging gas (a), the volatiles were then concentrated and trapped in the Tenax trap, cooled to -30°C by circulation of liquid nitrogen. By switching a rotary valve (4), carrier gas (b) flowed through the trap... 

Tenax trap) have also been optimized in order i) to obtain a total desorption of volatiles trapped on the auxiliary tube (confirmed by a blank chromatogram for a second heat desorption), ii) to avoid losses of volatiles during the adsorption phase (sensorially verified at the odor port). 

Identification of volatiles compounds A typical total ion current chromatogram of the Tenax trapped Black Truffle (Tuber Melanosporiim) volatiles is shown in Figure 4. 

The volatiles of the crown, pulp and whole intact fni it were examined by dynamic headspace sampling using a procedure developed in our laboratory (1 ). The method uses a fast flow of sweeping gas (3L/min) onto large Tenax traps. 

Solvents may also be used for desorption of porous polymer traps as discussed by Schaefer ( 23). Recently Parliment (2jl) described a micro solvent extraction apparatus for desorbing volatile organics from C-18 or Tenax traps. Less than a milliliter of solvent is used to desorb the volatiles from the trap, and the solvent is recycled to achieve complete desorption. 

---