Chromatograph column furnace

The system used by these workers consisted of a Microtek 220 gas chromatograph and a Perkin-Elmer 403 atomic absorption spectrophotometer. These instruments were connected by means of a stainless steel tubing (2mm o.d.) connected from the column outlet of the gas chromatograph to the silica furnace of the atomic absorption spectrometer. The silica furnace was set at 1000°C. The gas chromatographic column was packed with 3% OV-1 supported on Chromosorb W. The column was temperature programmed at 15°C h to 150°C. 

Ultraviolet-visible (UV-Vis) spectrophotometric detectors are used to monitor chromatographic separations. However, this type of detection offers very little specificity. Element specific detectors are much more useful and important. Atomic absorption spectrometry (AAS), inductively coupled plasma-atomic emission spectroscopy (ICPAES) and inductively coupled plasma-mass spectrometry (ICP-MS) are often used in current studies. The highest sensitivity is achieved by graphite furnace-AAS and ICP-MS. The former is used off-line while the latter is coupled to the chromatographic column and is used on-line . 

The carrier gas (1) can pass either directly from the stopcock (2) through the chromatographic column or through the sampling tube. For introduction of the sample this tube (4) is flash heated to about 130 C by a small electric furnace (3) positioned immediately above the injection port (5). 

A small quantity of the polymer is mounted on an inert metal support and an electrical current is passed through the support (filament method) or external heat is supplied to the support (furnace method) so as to rapidly heat up and break down (i.e., pyrolyse) the polymer into a mixture of smaller molecules which, under standard pyrolysis conditions, are characteristic of the polymer being examined. Products are swept from the pyrolysis chamber by a stream of carrier gas onto a gas chromatographic column and separated into their individual components before passing through the detector, which records their retention time (time taken, under standard conditions, to travel from pyrolysis chamber to detector) and quantity (peak height under standard conditions). 

Figure 10.4 shows a schematic representation of the multidimensional GC-IRMS System developed by Nitz et al. (27). The performance of this system is demonstrated with an application from the field of flavour analysis. A Siemens SiChromat 2-8 double-oven gas chromatograph equipped with two FIDs, a live-T switching device and two capillary columns was coupled on-line with a triple-collector (masses 44,45 and 46) isotope ratio mass spectrometer via a high efficiency combustion furnace. The column eluate could be directed either to FID3 or to the MS by means of a modified Deans switching system . 

Furnace, Curie-point or heated filament pyrolysers linked to packed column or capillary column gas chromatograph. GC-MS or GC-FT-IR interfaces. 

The essential apparatus for pressure measurement and analysis, and other important aspects such as furnaces and temperature control, are reviewed for thermal, photochemical and radiochemical systems. The latter two also involve sources of radiation, filters and actinometry or dosimetry. There are three main analytical techniques chemical, gas chromatographic and spectroscopic. Apart from the almost obsolete method of analysis by derivative formation, the first technique is also concerned with the use of traps to indicate the presence of free radicals and provide an effective measure of their concentration. Isotopes may be used for labelling and producing an isotope effect. Easily the most important analytical technique which has a wide application is gas chromatography (both GLC and Gsc). Intrinsic problems are those concerned with types of carrier gases, detectors, columns and temperature programming, whereas sampling methods have a direct role in gas-phase kinetic studies. Identification of reactants and products have to be confirmed usually by spectroscopic methods, mainly IR and mass spectroscopy. The latter two are also used for direct analysis as may trv, visible and ESR spectroscopy, nmr spectroscopy is confined to the study of solution reactions... 

The reactor consisted of a quartz tube (12 in. long, 1/2 in diameter) and was heated by a 1200 watt furnace with a feed back temperature controller. The catalyst was placed in powder form on a porous frit, and its temperature was measured by a chrome1 Alumel thermocouple inserted into a thermowell. The reactor inlet and outlet compositions were measured by an on line gas chromatograph (G.C.) equipped with an 18 ft long, 1/8 in O.D column filled with 80/100 Porapak S and operated at 115°C using He as a carrier gas. An ice bath, placed between the reactor exit and the G.C. sampling valve, condensed the steam and removed the water. 

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