Carrier gas chromatography

Urano, K.,Ogura, K., Wada, H. (1981) Direct analytical method for aliphatic compounds in water by steam carrier gas chromatography. Water Res. 15, 225-231. 

Gas phase chromatography is a separation method in which the molecules are split between a stationary phase, a heavy solvent, and a mobile gas phase called the carrier gas. The separation takes place in a column containing the heavy solvent which can have the following forms ... 

In gas chromatography (GC) the sample, which may be a gas or liquid, is injected into a stream of an inert gaseous mobile phase (often called the carrier gas). The sample is carried through a packed or capillary column where the sample s components separate based on their ability to distribute themselves between the mobile and stationary phases. A schematic diagram of a typical gas chromatograph is shown in Figure 12.16. 

Gas Chromatography. Gas chromatography is a well recognised method for the analysis of H—D—T mixtures. The substrate is alumina, AI2O2, coated with ferric oxide, Fe202. Neon is used as the carrier gas. Detectors are usually both thermal conductivity (caratherometer) and ion chamber detectors when tritium is involved (see Chromatography). 

Small amounts of pyridine have been purified by vapour-phase chromatography, using a 180-cm column of polyethyleneglycol-4(X) (Shell 5%) on Embacel (May and Baker) at 100°, with argon as carrier gas. The Karl Fischer titration can be used for determining water content. A colour test for pyrrole as a contaminant is described by Biddiscombe et al. [J Ghent Soc 1957 1 954]. 

Fig. 17. A schematic of the alkane line obtained by inverse gas chromatography (IGC) measurements. The relative retention volume of carrier gas required to elute a series of alkane probe gases is plotted against the molar area of the probe times the. square root of its surface tension. The slope of the plot is yielding the dispersion component of the surface energy of...

Another method to determine infinite dilution activity coefficients (or the equivalent FFenry s law coefficients) is gas chromatography [FF, F2]. In this method, the chromatographic column is coated with the liquid solvent (e.g., the IL). The solute (the gas) is introduced with a carrier gas and the retention time of the solute is a measure of the strength of interaction (i.e., the infinite dilution activity coefficient, y7) of the solute in the liquid. For the steady-state method, given by [FF, F2] ... 

The detector. The function of the detector, which is situated at the exit of the separation column, is to sense and measure the small amounts of the separated components present in the carrier gas stream leaving the column. The output from the detector is fed to a recorder which produces a pen-trace called a chromatogram (Fig. 9.1fr). The choice of detector will depend on factors such as the concentration level to be measured and the nature of the separated components. The detectors most widely used in gas chromatography are the thermal conductivity, flame-ionisation and electron-capture detectors, and a brief description of these will be given. For more detailed descriptions of these and other detectors more specialised texts should be consulted.67 69... 

Thermal conductivity detector. The most important of the bulk physical property detectors is the thermal conductivity detector (TCD) which is a universal, non-destructive, concentration-sensitive detector. The TCD was one of the earliest routine detectors and thermal conductivity cells or katharometers are still widely used in gas chromatography. These detectors employ a heated metal filament or a thermistor (a semiconductor of fused metal oxides) to sense changes in the thermal conductivity of the carrier gas stream. Helium and hydrogen are the best carrier gases to use in conjunction with this type of detector since their thermal conductivities are much higher than any other gases on safety grounds helium is preferred because of its inertness. 

Ethanol production in the fermentation process was detected with gas chromatography, HP 5890 series II (Hewlett-Packard, Avondale, PA, USA) equipped with a flame ionisation detector (FID) and GC column Porapak QS (Alltech Associates Inc., Deerfield, IL, USA) 100/120 mesh. The oven and detector temperature were 175 and 185 °C, respectively. Nitrogen gas was used as a carrier. Isopropanol was used as an internal standard. 

Gas chromatography on a 200 cm. by 0.6 cm. column packed with 10% Apiezon L on Chromosorb W (AW, DMCS) using a flame-detector instrument, at a 40 ml./minute helium carrier gas flow rate, gives a trace peak at 9.9 minutes (diphenylmethane), a major peak at 11.7 minutes (1,1-diphenylethane), and a trace peak at 15.4 minutes (1.1-diphenylethanol) when the oven is held at 190° for 10 minutes and then programmed at 10°/minute to 290°. 

Slagt et al. [134] have stated that because of their thermal instability and reactivity sultones could not be easily analyzed by gas chromatography. They studied the two methods published by Martinsson and Nilsson using a Carlo Erba Fractovap G1 equipped with a flame ionization detector and a glass column (length 0.65 m OD 1/4 in.) filled with 10% OV 1 on Chromosorb W-AW (80-100 mesh). The column temperature was 230°C and the injector/de-tector temperature 275°C. The gas flow rates were N2 25 ml/min (carrier gas), H2 25 ml/min, and air 250 ml/min. One microliter of sample was injected. 

Unlike gas chromatography, in which the mobile phase, i.e. the carrier gas, plays no part in the separation mechanism, in HPLC it is the relative interaction of an analyte with both the mobile and stationary phases that determines its retention characteristics. Hence, it is the varying degrees of interaction of different analytes with the mobile and stationary phases which determines whether or not they will be separated by a particular HPLC system. 

The checkers found considerable variation in the rate of the reaction in different runs, the time required for its completion ranging from 3 to 10 hours. It is therefore advisable to monitor the progress of the reaction. For this purpose small aliquots (ca. 0.05 ml.) were withdrawn from the flask with a syringe and hydrolyzed by injection into a vial containing ether and saturated ammonium chloride. The relative amoimts of enol silane and cyclopropoxy sdane were determined by gas chromatography on an 0.6 cm. X 3.7 m. column of 3% OV-17 coated on 100-120 mesh Chromosorb W. With a column temperature of 120° and a carrier gas flow rate of 20 ml. per minute, the retention times for the enol silane and the cyclopropoxy silane are ca. 1.9 and 2.3 minutes, respectively. 

In contrast to other organothallium(I) compounds, cyclopentadienyl-thallium(I) is a remarkably stable compound. Samples can be stored in sealed bottles for months without appreciable decomposition occurring it is unaffected by water and dilute alkali and it is only slowly oxidized by air at room temperature. Cyclopentadienyltballium(I) was first prepared by Meister in 1956 by addition of freshly distilled cyclopentadiene to a suspension of thallium(I) sulfate in dilute potassium hydroxide solution 101, 102). A number of variations of this procedure have been described (5, 25, 34, 56), and the compound has been made in other ways 35, 56,110, 164), but Meister s preparation, in which the yield of crude product is greater than 90%, remains the method of choice. Purification of crude cyclopenta-dienylthallium(I) is best accomplished by vacuum sublimation, and purity of samples can readily be assessed by gas-liquid chromatography on silicone oil at 170° C using hydrogen as carrier gas (7). 

Experiments of propane pyrolysis were carried out using a thin tubular CVD reactor as shown in Fig. 1 [4]. The inner diameter and heating length of the tube were 4.8 mm and 30 cm, respectively. Temperature was around 1000°C. Propane pressure was 0.1-6.7 kPa. Total pressure was 6.7 kPa. Helium was used as carrier gas. The product gas was analyzed by gas chromatography and the carbon deposition rate was calculated from the film thickness measured by electron microscopy. The effects of the residence time and the temperature... 

Catalytic activity tests have been performed in a quartz microreactor (I.D.=0.8 cm) filled with 0.45 g of fine catalyst powders (dp=0 1 micron). The reactor has been fed with lean fiiel/air mixtures (1.3% of CO, 1.3% of H2 and 1% of CH4 in air resp ively) and has been operated at atmospheric pressure and with GHSV= 54000 Ncc/gcath The inlet and outlet gas compositions were determined by on-line Gas Chromatography. A 4 m column (I D. =5mm) filled with Porapak QS was used to separate CH4, CO2 and H2O with He as carrier gas. Two molecular sieves (5 A) columns (I D.=5 mm) 3m length, with He and Ar as carrier gases, were used for the separation and analysis of CO, N2, O2, CH4, and H2, N2, O2 respectively... 

---