Construction of a thermodesorption injector for gas chromatography

Abstract

A detailed description for the do-it-yourself construction of a high-performance thermodesorption GC injector (HPTI) is presented. The injector consists of a heated desorption chamber, a cooled loop for focusing the desorbed volatiles as well as a heating control for sample injection into the separation column. The gas flow is controlled by valve switching during the steps of the operation. Two versions of the injector function either for the injection of highly volatile compounds or for compounds with extremely low volatility, e.g. lubricants. The sophisticated gas flow management allows injection of highly concentrated samples without memory effects in a sample gas split mode, while traces may be injected with virtually 1:1 sample transfer. A wide range of adsorbents appropriate for the compounds can be chosen due to homemade adsorbent tubes and the achievability of high desorption temperature. Solutions may be injected from a carrier material after solvent evaporation. The HPTI fulfills all multipurpose GC injector requirements and with the support of downloadable instruction files can be built by anyone working with conventional GC devices.

Volatile S-nitrosothiols and the typical smell of cancer

“…Odorous compounds are found to be invariably part of the human body, and breath is the main emission source of body volatiles. The author's broad-based measurements of breath samples as part of the research for a doctoral thesis at the University of Kiel (Germany) [15], revealed that thiols, sulfides and disulfides with molecular carbon structures based on methane-, ethane-, propane-and propene-groups are omnipresent (detected by a specially optimized very effective thermal desorber coupled to high performance gas chromatography/mass spectrometry (GC/MS) [16]). These compounds provide evidence for the complex sulfur chemistry credited principally with important physiological processes in the body and from microbial fermentation (described in [17][18][19]).…”

Thermal desorption gas chromatography with mass spectrometry study of outgassing from polymethacrylimide foam (Rohacell®)

“…In addition, when dealing with solid samples, all the GC injection requirements are superbly managed using a thermal desorption (TD)/sorption system. In particular, with TD injection both resolution and limits of detection are largely improved, which is particularly useful when the analytes should be preconcentrated from large volumes, as occurs in the investigation of air pollutants, when the sample contains components largely differing in volatility, or when slowly outgassing from a solid sample should be monitored [18][19][20]. Jansen et al [21] used TD-GC coupled to FTIR spectroscopy detection to study outgassing from dimethylpolysiloxane (silicone), polyoxymethylene and poly(methyl-methacrylate).…”