Glycols Tenax

Glycol ether and glycol acetate vapours in air Lab method using Tenax sorbent tubes, thermal desorption and gas chromatography 23... 

Glycol ether and glycol ether acetate vapours m air (Tenax adsorbent tubes)... 

Solid and liquid waste, soil Dispersion in glycol purge-and-trap pre-concentration onto Tenax/ silica/charcoal thermal desorption GC/ECD and FID in series No data 105 at 5 pg/L Lopez-Avila et al. 1987... 

Compared with whole air sampling into Tedlar bags and canisters, active sampling onto sorbent materials is used more widely in these indoor air quality (lAQ) studies. Only a few studies made use of organic vapour monitor passive samplers. Of the sorbent materials used, Tenax is the most frequently employed, possibly because of its virtues, which are mentioned in Sect. 4.2.1. It has been used for the characterisation of aromatics, alkenes, cycloalkanes, aldehydes, ketones, esters, alcohols, terpenes, glycol derivatives and even amines [33,59]. 

TENAX TA is the recommended adsorbent for active sampling of glycols in indoor air. In combination with thermal desorption and GC/MS- or GC/FID-analysis, this method shows sufficient selectivity and sensitivity (Clausen et al., 1990 Hansen et al., 1987). However, the identification of higher glycols via low-resolution MS is somewhat sophisticated, because the mass peaks are not characteristic. In case of 1,2-PGMM and 1,2-PG the mass spectra are almost identical, with relevant m/z-values of 59, 45, 103 and 73. Therefore, retention indices and standard compounds are required for an exact classification (Uhde et al., 1999). 

The elution of the organic compounds collected involves extraction by a solvent (displacement) or thermal desorption. Pentane, CS2 and benzyl alcohol are generally used as extraction solvents. CS2 is very suitable for activated charcoal, but cannot be used with polymeric materials, such as Tenax or Amberlite XAD, because decomposition occurs. As a result of displacement with solvents, the sample is extensively diluted, which can lead to problems with the detection limits on mass spectrometric detection. With solvents additional contamination can occur. The extracts are usually applied as solutions. The readily automated static headspace technique can also be used for sample injection. This procedure has also proved to be effective for desorption using polar solvents, such as benzyl alcohol or ethylene glycol monophenyl ether (1% solution in water, Krebs, 1991). 

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