Thermal conductivity detection

Figure 27-5 Diagram of C.H.N.S elemental analyzer that uses gas chromatographic separation and thermal conductivity detection. [Adapted from E. Pella, Elemental Organic Analysis. 2. State of the Art, Am. Lab, August 1990, p. 28.]...

Thermistor bead element. A thermal conductivity detection device in which a small glass-coated semiconductor sphere is used as the variable resistive element in the cell chamber. 

Corning high-vacuum silicone grease on Gas-Chrom 175°, with thermal conductivity detection and He as carrier gas. above. ... 

Reactor effluent was continuously fed to a 0.25 ml sampling loop located inside a Hewlett-Packard Model 2520 Gas Analyzer. Separation of the products was over two serial columns, 6 x 1/8" Poropak Q 80/100 mesh, followed by 10 x 1/8" molecular sieve 5A 60/80 mesh. Thermal conductivity detection was used with helium carrier gas. Columns were isothermal at 60 C. 

The thermal chromatograph is the instrument of choice for the heating of small (mg) shale samples. These are heated under controlled conditions of temperature increase under a chosen atmosphere, and volatiles produced are carried directly through thermal conductivity and/or fiame ionization detectors. After trapping of all or part of the evolved species, GC may be carried out. A typical pyrolysis profile of the total volatiles produced with respect to temperature for both types of detection is shown in Figure 11. The characteristic twin-humped curve is seen with thermal conductivity detection. The latter hump, which is absent... 

Arsine, present as an impurity in acetylene, has been determined on a column packed with tritolyl phosphate on Chromosorb 102 at 30 °C with hydrogen or helium as carrier gas, and thermal conductivity detection. Peaks were obtained for nitrogen, methane, arsine, hydrogen sulphide and phosphine. 

Fig. 2 An example chromatogram illustrating the determination of headspace oxygen by GC using a PLOT molecular sieve column with thermal conductivity detection. Chromatographic conditions were carrier gas helium (2mLmin ) oven temperature 26 C inlet 160 C, split mode, 10 1 split ratio, split flow of 20mLmin injector 160°C run time lOmin TCD detector 160 C. (From Ref. p. 41. Copyright 2002 Advanstar Communications Inc.)...

Following the separation of pyrolysates, the detection can be done using common procedures for GC such as thermal conductivity detection, flame ionization detection (FID), etc. However, nonselective detectors without the identification capability are less common than mass spectrometric detection. While a GC separation with FID detection can provide only a fingerprint chromatogram for a specific polymer pyrolysate, mass spectrometry allows, at least in principle, the identification of pyrolysate components. 

Several commercial evidential breath alcohol measurement devices are available. The principle of measurement is either infrared absorption spectrometry (most common), dichromate-sulfuric acid oxidation-reduction (photometric), GC (flame ionization or thermal conductivity detection), electrochemical oxidation (fuel cell), or metal-oxide semiconductor sensors. A list has been published of DOT-approved breath alcohol devices.Some of these devices are approved for screening only. In this case, the second or confirmatory breath alcohol determination must be performed with an approved evidential breath alcohol analyzer. Breath alcohol devices may also be used for the medical evaluation of patients at the point of care (e.g., emergency department). A Fourier transform infrared point-of-care breath analyzer capable of measurement of... 

Bll. Beroza, M., and Sarmiento, R., Carbon skeleton chromatography using hot-wire thermal conductivity detection. Anal. Chem. 36, 1744-1750 (1964). 

An experimental study has been carried out with peat samples from the forest area of Brunei Darussalam. We should note here that the measurement of emission products requires comprehensive analytical equipment. Hydrocarbons (C1-C4) are determined by gas chromatography with flame ionization detection (GC/FID), CO2 and O2 are analyzed by gas chromatography with thermal conductivity detection (GC/TCD), and CO, by gas chromatography with electron capture detection (GC/ECD). Aldehydes and polynuclear aromatic hydrocarbons (PAHs) are determined by gas chromatography with mass spectrometry (GC/MS). 

Experiment 21. Study of some important parameters in GC Experiment 22. The determination of some chlorinated insecticides by capillary GC using an EC detector Experiment 23. Analysis of paint shop vapours Experiment 24. The determination of water content in solvents by capillary and packed GC using thermal conductivity detection Experiment 25. Analysis of mineral acids as their cyclohexyl derivatives by capillary GC and GC-MS... 

An alternative approach is first to analyse the sample, noting the area, Ai, for the analyte. Successive standard amounts of the analyte are then added, each sample + standard mixture being analysed and the areas recorded. A graph of peak area versus concentration is drawn and the amount of analyte in the sample obtained by projection of the calibration line to intersect the abscissa as shown in Figure 2.9. This approach is conveniently illustrated by the determination of water in methanol by GC using thermal conductivity detection experiment 24, Chapter 9. 

Determination of water content in solvents by capillary and packed GC using thermal conductivity detection. 

Water, packed and capillary columns, external standard, thermal conductivity detection. 

Figure 22.9. Typical bridge configuration for thermal conductivity detection. Courtesy of Gow-Mac Instrument Co.

FJMBMS at SERI and a Hewlett-Packard 5890 gas chromatograph/5970 Mass Selective Detector (GC/MSD) using a 1.5-m high-performance cross-linked methyl silicone capillary column. The noncondensible gases were analyzed with a Carle GC designed for refinery gas analysis, which used thermal conductivity detection (TCD) and was calibrated with a gravimetrically prepared reference mixture. Electronic grade methanol (99.9% pure) was used for comparison to the softwood feedstock. 

Ammonia Liberation from Heat Treated PAM Perkin Elmer Sigma 2 equipped with Thermal Conductivity Detection column 6ft.xl/8... 

Rapid automated systems, employing high-temperature combustion for removal of the nitrogen from the sample and a thermal conductivity detection system for measurement of the released... 

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