He carrier gas

The spectrometer is fitted with a skimmed c.w. supersonic molecular beam source. Many chiral species of interest are of low volatility, so a heated nozzle-reservoir assembly is used to generate, in a small chamber behind a 70-pm pinhole, a sample vapor pressure that is then seeded in a He carrier gas as it expands through the nozzle [103], Further details of this apparatus are given elsewhere [36, 102, 104],... 

Conditions apparatus, Hewlett-Packard HP5890 equipped with an HP5972 mass-selective ion detector (quadruple) column, PTE-5 (30 m x 0.25-mm i.d.) with 0.25- am film thickness column temperature, 50 °C (1 min), increased at 20 °C min to 150 °C(5 min) and then at 4 °Cmin to 280 °C (30 min) inlet and detector (GC/MS transfer line) temperature, 250 and 280 °C, respectively gas flow rate, He carrier gas ImLmin" injection method, splitless mode solvent delay, 3 min electron ionization voltage, 70eV scan rate, 1.5 scanss scanned-mass range, m/z 50-550. The retention times of benfluralin, pendimethalin and trifluralin are 15.2, 25.1 and... 

In the above-mentioned method by Hodgeson el acifluorfen was determined by GC/ECD after the extraction with a 47-mm PS-DVB disk and derivatization with diazomethane. The conditions for GC/ECD were as follows column, DB-5 fused silica (30 m X 0.32-mm i.d., 0.25-p.m film thickness) He carrier gas velocity, 25 cm s (210°C), detector makeup gas, methane-argon (5 95), 30mLmin column temperature, 50 °C (5 min), 10°Cmin to 210 °C (5 min) and to 230 °C (10 min) injection port and detector temperature, 220 and 300 °C, respectively injection method, splitless mode. The recovery of acifluorfen from purified water, dechlorinated tap water and high humic content surface water fortified at 0.5-2.0 ug was 59-150% and the LOD was 25 ngL Acifluorfen after derivatization with various chlorofor-mates was also determined by GC/MS using an SE-54 column (25 m x 0.20-mm i.d., 0.32- um Aim thickness), and the average recovery of acifluorfen fortified between 0.05 and 0.2 ugL was 78%. ... 

Figure 5.19 Formation of amino acids on ice surfaces irradiated in the laboratory (Nature Nature 416, 403-406 (28 March 2002) doi 10.1038/416403a-permission granted). Data were obtained from analysis of the room temperature residue of photoprocessed interstellar medium ice analogue taken after 6 M HCl hydrolysis and derivatization (ECEE derivatives, Varian-Chrompack Chirasil-L-Val capillary column 12 m x 0.25 mm inner diameter, layer thickness 0.12 pirn splitless injection, 1.5 ml min-1 constant flow of He carrier gas oven temperature programmed for 3 min at 70°C, 5°C min-1, and 17.5 min at 180°C detection of total ion current with GC-MSD system Agilent 6890/5973). The inset shows the determination of alanine enantiomers in the above sample (Chirasil-L-Val 25 m, single ion monitoring for Ala-ECEE base peak at 116 a.m.u.). DAP, diaminopentanoic acid DAH, diaminohexanoic acid a.m.u., atomic mass units.

Fig. 7 Thermogravimetric weight loss curve (A) and subsequent IR spectra measured at the designated temperatures (B) 70°C, (C) 95°C, (D) 120°C, (E) 160°C, and (F) 180°C. A slight lag time exists between the TG weight loss and IR spectral acquisition due to the evolved gas being carried into the IR gas cell by the He carrier gas. Each IR spectrum is plotted on the same absolute intensity scale (Abs. units).

The lower activation energies found for p-type a-Si H using the evolution technique may be due to microstructure in the films grown with a He carrier gas. The higher D0 obtained in doped samples using the concentration profiling technique results from the correction of the data to a constant diffusion distance L = 1000 A (Jackson et al., 1989a). 

Meta-xylene isomerization to ortho- and para-xylene over 10- and 12-MR zeolites is another illustration of product shape selectivity effects [13]. The two products are essentially equally favorable from the standpoint of thermodynamics. With decreasing pore size, however, kinetics come into play and the selectivity to para-xylene increases, as illustrated in Figure 13.37 for results obtained at 317-318°C, 0.5 kPa meta-xylene pressure (in the presence of He carrier gas) and 10% conversion [64]. While the para ortho ratio is typically 1.0-1.5 with multi-dimensional... 

Batch slurry reactions were carried out in liquid phase in a stirred glass vessel with condenser. Catalyst was added to a preheated solution containing aromatic reactant (35ml, Aldrich) and iso-butyric anhydride (16ml, Aldrich) in a 3 1 molar ratio. Samples of the reaction mixture were removed from the reaction mixture after various reaction times, filtered and analysed by gas chromatography (column DB-5, 30m, He carrier gas, FID detector) to determine reaction progress. Product identification was made by comparison with appropriate reference materials. 

For the baseline calculations, assume the following operating parameters and conditions pressure 200 Torr, inlet manifold temperature 22°C, disk rotation rate 450 rpm, disk temperature 650°C, and distance between the disk and the inlet 6.2 cm. Assume that the inlet reactant gas mixture is 0.33 Torr of SM4 in a He carrier gas. You may use the gas-phase and surface reaction mechanisms silicon. gas and silicon. surf. 

Sampling is performed with two high pressure switching valves with internal volume. 5 pi (for the upper phase) and. 2 pi for the lower or middle phases. The samples are directly depressurized into a He carrier gas stream and analyzed with a Perkin Elmer Sigma 2 Gas Chromatograph, using a Porapak Q column supplied by Supelco. The response factors for the materials used were found to be close to those reported by Dietz (2). Typical reproducibility of the analysis is .003 in mole fraction, with somewhat larger deviations for the gas-phase compositions at low pressures. 

The large difference in gallery heights for Cr3 53 and Cr1 88-montmorillonites leads to dramatic differences in catalytic reactivity (17). Figure 4 illustrates the conversion of cyclohexane to benzene over both materials at 550°C as a function of reaction time. Both catalysts were pre-reduced under H2 in a continuous flow reactor at 500°C, followed by reaction with cyclohexane (weight hourly space velocity = 3, contact time = 6 sec, He carrier gas.) The clay remains intact at these reaction temperatures as evidenced from the thermal data (17). 

The dimethylated derivatives of the mixture of 5a and 5c were submitted to analysis on the LKB-9000 GLC-MS with AVA described previously. Samples were chromatographed at 250°C on a 6 column of OV-17, 2%, on Supelcoport (80/100 mesh) with a He carrier gas flow rate of 30 ml/minute. The ratio of the peak heights at m/e 372 and 375 was determined in the usual manner. 

Analysis of the products of methane decomposition was performed gas chromatographically SRI- 8610A (TCD, Ar-carrier gas, silica gel) and Varian-3400 (FID, He-carrier gas, HysepDb), and spectrophotometrically (Spectronic 60 1). 

Helium ionization (HID) photoionization He carrier gas ionized Universal, but 25... 

Temperature Programmed Oxidation. Determination of the amount of deposited carbon was performed by oxidation using 5% 02 in N2. Fractured catalyst samples (0.15-0.425 mm) were oxidized immediately after performing the test reaction using a heating rate of 3°C/mm. Carbon was detected as C02 in a gas chromatograph (Porapak Q column, 1/8", 2.5 m He carrier gas at 160°C) equipped with a thermal conductivity detector. 

For studies of element 108 (Hs) and element 112 the new device named In-situ Volatilization and On-line detection (IVO) was developed [124], By adding 02 to the He carrier gas, volatile tetroxides of group-8 elements were formed in-situ in the recoil chamber. A quartz column containing a quartz wool plug heated to 600°C was mounted as close as possible to the recoil chamber. The hot quartz wool served as an aerosol filter and provided a surface to complete the oxidation reaction. For future studies with element 112 pure He or even a reducing He/H2 mixture can be employed. 

The A1 1b dissolved in 6 H HC1 containing Fe++, PtCl and NHj carrier. After addition of 10 N NaOH, the evolved NHa gas is swept out and caught in 1 N NaGH + KMnO soln. at 0 C. Or by heating the soln., the NHa gas is distilled by aid of He carrier gas and caught in aat. HaBOa soln. containing a definite amount of HC1. After addition of NaOH to the boric acid soln., the NHa is distilled once again Into a similar sat. 66... 

Using He carrier gas, the radioactive gas is swept through H2SQ4 to remove HeO, Ascarlte to remove CQ2,... 

The TPD apparatus consisted of a stainless steel flow system connected to a thermal conductivity cell. Catalyst samples of 0.1 g were placed in one arm of an L-shaped, 6 mm Vycor tube. A dual adsorption bed containing alumina and Oxy-Trap (Alltech) was placed in the other arm to prevent contamination by water and respectively. Frequent regeneration in and He was required. This in-situ adsorption bed was found necessary despite purification traps on all gas lines coming into the flow system. Pulses of 0.25 cc of a 10% mixture of CO in He were injected into the He carrier gas and passed over the pretreated catalyst at room temperature. All runs were programmed heated at a rate of 20 K min . The Pt catalysts, either commercial or laboratory produced, were prepared by the impregnation of chloroplatinic acid on Cyanamid s Aero 1000 alumina, except for two catalysts which were prepared by platinum diamino dinitrite impregnation. 

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