Thermal membrane desorption

Utilization of an extraction membrane as analyte collecting medium in combination with thermal desorption Thermal Membrane Desorption Application - TMDA)... 

Matz, G., Kibelka, G., Dahl, J., Leimeman, F. Experimental study on solvent-less sample preparation methods - membrane extraction with a sorbent interface, thermal membrane desorption application and purge-and-trap. J. Chromatogr. 830, 365-376 (1999)... 

After this isolation step, analytes are usually concentrated in sorbent traps (membrane extraction sorbent interface [MESI]) and thermally desorbed in a cryofocusing device or directly in a gas chromatographic column. In other cases,no sorbent trap is used, analytes are desorbed directly from the membrane unit cell (thermal membrane desorption [TMD]) and carried by a gas stream onto the front of the chromatographic column of the analytical system. 

Diffusive sampler Membrane extraction (MESI) Liquid-liquid extraction (LLE) Solid-phase extraction (SPE) SPE-PTV-GC Solid-phase microextraction (SPME) Headspace GC (SHS, DHS) Large-volume injection (LVI) Coupled HPLC-GC Membrane extraction (MESI) Difficult matrix introduction (DMI) Conventional solvent extraction methods 1 Pressurised solvent extraction methods Headspace GC (SHS, DHS) Thermal desorption (TD, DTD) Pyrolysis (Py) Photolysis Photon extraction (LD) Difficult matrix introduction (DMI)... 

With a focus on trace forensic detection of explosives, especially for use in counterterrorism and to counter narcotics investigations, Fetterolf et al. [75] evaluated the use of ion mobility-mass spectrometry for explosives determinations. In this, explosives residues were collected on a membrane filter by a special attachment on a household vacuum cleaner. Although subsequent thermal desorption and analysis required only 5 s, fimits of detection for most common explosives were as low as 200 pg. The persistence of explosives on hands and transfer to other surfaces were also examined as were post-blast residues of NG on fragments of improvised explosive devices constructed with double-based smokeless powder. Finally, postblast residue from C-4, Semtex, and other explosives was found by IMS analyses on items of forensic and evidentiary value. These few out of many examples demonstrate that mobihty spectrometers are well suited tools for laboratory and on-site investigations, before and after the use of explosives. 

T0502 McLaren/Hart, Inc., IRV-100, IRV-150, and IRV-200 Thermal Desorption Systems T0504 Medina Agricnlmral Products Company, Inc., Medina Bioremediation Products T0506 Membran Corporation, Membrane Gas Transfer... 

Gore-Sorber Hydrophobic adsorbent Microporous membrane of polytetrafluoroethylene— GORE-TEX BTEX, MTBE, PAHs. VOCs, semi-VOCs Equilibrium 14 days Thermal desorption 61... 

The most important water treatment technologies are summarized in Fig. 5-6. Depending on the source and on the water quahty, either mechanical, biological, physical, thermal, or chemical processes or their combinations may be applied. Photochemical AOPs and AOTs are subordinated to chemical processes, mainly because the current technological versions of photochemical wastewater remediation are dependent on the addition of auxihary oxidants, such as hydrogen peroxide, ozone or special catalysts such as titanium dioxide. Photochemical AOPs are attractive alternatives to non-destructive physical water treatment processes, for example adsorption, air stripping or desorption and membrane processes. The last merely transport contaminants from one phase to another, whereas the former are able to minerahze organic water contaminants (cf. Chapter 1). 

FIGURE 25.17 (a) SEM cross-section image of a microporous silica membrane with nanodispersed ZnO (designated as SZ4). (b) Evolution of the x-ray pattern for an SZ4 powder, (c) Evolution of the Nj adsorption-desorption isotherm for an SZ4 powder. A initial state B after contact with HjS Cl and C2 after thermal regeneration. (From Goswamee, R., Bose, E, Cot, D., El Mansouri, A., Lopez, M., Morato, F., and Ayral, A., / Sol-Gel Sci. Technol, 29, 97, 2004.)... 

C. Lanzerstorfer, H. Puxbaum, The palladium/silver membrane focusing injector-a new inlet system for thermal desorption capillary gas chromatography, Fresenius J. Anal. Chem. 1991, 339(4). 223-225. 

Generally, it is allowed that pervaporate transport is isothermal, but there is however a thermal effect due to evaporation on the permeate-side. The temperature is one of parameters influencing the transfer acceleration of the diffusion in the film boundary layer and the membrane, modification of sorption on the membrane (generally, lowering), and improvement of desorption in the downstream interface. 

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