Nitrogen as carrier gas

We studied the polyamidation of nylon 4,6, and varied the reaction time, reaction temperature, partical size, starting molecular weight, and type of reactor gas. At the same time we looked at the molecular weight broadening and the degradation with colour formation. In order to have good heat and mass transfer the reactions were mainly conducted on fine powder in a fluidized bed reactor and with dry nitrogen as carrier gas. 

The SPP in a fluidized bed reactor with dry nitrogen as carrier gas allows us to study the reaction under anhydrous conditions. However under these conditions the products were found to be coloured (table IV). 

Abbott et al. [163] described a pyrolysis unit for the determination of Picloram and other herbicides in soil. The determination is effected by electron capture-gas chromatography following thermal decarboxylation of the herbicide. Hall et al. [164] reported further on this method. The decarboxylation products are analysed on a column (5mm i.d.) the first 15cm of which is packed with Vycor chips (2-4mm), the next 1.05m with 3% of SE-30 on Chromosorb W (60-80 mesh) and then 0.6m with 10% of DC-200 on Gas Chrom Q (60-80 mesh). The pyrolysis tube, which is packed with Vycor chips, is maintained at 385°C. The column is operated at 165°C with nitrogen as carrier gas (110ml min-1). The method when applied to ethyl ether extracts of soil gives recoveries of 90 5%. Dennis et al. [165] have reported on the accumulation and persistence of Picloram in bottom deposits. 

In 1953, Billings et al. (17) studied the water vapor reaction with a lssHg source. The experiments were carried out in a flow system with nitrogen as carrier gas. The mercury oxide formed was found to be enriched in mHg, relative to its natural abundance. Similarly, with a -"-Hg lam)), an enriclnnent in 2,2Hg was observed (18). The isotopic analysis of mercury product in these studies was made by interferometry. 

Figure 1. Evolution of hydrogen chloride at 180° C (nitrogen as carrier gas) from suspension PVC (1), suspension FVC + stabilizer (2), ds-l,4-polybuta-diene-PVC (suspension) graft copolymer from monomeric butadiene (Type M) (3), Type M graft copolymer + stabilizer (4), and graft copolymer from cis-1,4-polybutadiene (Type P) (5)...

Soderquist et al. [10] determined hydroxydimethylarsine oxide in soil by converting it to iododimethylarsine using hydrogen iodide followed by determination at 105 °C on a column (450 cm x 2.8 mg) packed with 10% DC-200 on Gas-Chrom Q (60-80 mesh), with nitrogen as carrier gas (20-30 min 1) and electron capture direction. The recovery of hydroxydimethylarsine oxide (0.15 ppm) added to soil was 91.3 5.1%. 

Beezhold and Stout [68] studied the effect of using mixed standards on the determination of PCBs. Mixtures of Arochlors 1254 and 1260 were used as comparison standards and gas chromatograms of these mixtures were compared with those obtained from a hexane extract of the sample after clean-up on a Florasil column. Polychlorinated biphenyls were separated from DDT and its analogues on a silica gel column activated for 17h and with 2% (w/w) of water added. The extracts were analysed on a silanised glass column packed with 5% DC-200 and 7.5% QF-1 on Gas Chrom Q (80-100 mesh) operated at 195°C with nitrogen as carrier gas (50-60mL min-1) and a tritium detector. 

Hermanson el al. [71] used an aluminium column (276cmx4mm) packed with 80-100 mesh Chromosorb W supporting 8.9% of amine 220 at 95°C with nitrogen as carrier gas and flame ionisation detection. A rectilinear response was obtained between peak area and amount of propylamine, dipropylamine, and propanol between 0.2 and 2.0gg. 

Getzendaner s method [199] for determining Dalapon (2,2 dichloropropionic acids is applicable to plant tissues and body fluid and doubtlessly to water samples. The sample was extracted with ethyl ether and the residue was analysed by gas chromatography on a glass column (1.2mx 2mm) of 4% LAC-2R plus 0.5% of phosphoric acid on Gas Chrom S (60-80 mesh) at 100°C with nitrogen as carrier gas (85mL min-1) and electron capture detection. Recoveries of about 90% were obtained for lOppm of the herbicide. 

Dressman [694] used the Coleman 50 system in his determination of dialkylmercury compounds in river waters. These compounds were separated in a glass column (1.86mx2mm) packed with 5% of DC-200 plus 3% of QF-1 on Gas Chrom Q (80-100 mesh) and temperature programmed from 70 to 180°C at 20°C min-1, with nitrogen as carrier gas (50mL min ). The mercury compound eluted from the column was burnt in a flame ionisation detector, and the resulting free mercury was detected by a Coleman mercury analyser MAS-50 connected to the exit of the flame ionisation instrument down to 0.1 mg of mercury could be detected. River water (1L) was extracted with pentane-ethyl ether (4 1) (2 ><60mL). The extract was dried over sodium sulphate, evaporated to 5mL and analysed as above. 

GC Retention time indices (Ig) The Ig values were calculated by linear interpolation of the unknown between retention times of a series of methyl esters of normal carboxylic acids under the GC conditions cited for OV-17 column and nitrogen as carrier gas. The method was similar to the one suggested by Van den Dool and Kratz (4j. The I value of each standard was arbitrarily given the carbon number of the acid of the ester thus hexanoate was given a value of 6.0. The IF values of the various peaks in the total extracts (SDE method) of all the three samples and of various authentic compounds were determined under corresponding GC conditions using the same column. 

Models were applied to the results obtained in the first collector, since the extract obtained in the second collector was made up of water and some volatiles that can not be separated. A Hewlett Packard 5890 Series II fitted with a flame ionisation detector was used to analyse the extract obtained in the first collector. A capillary column HP5 (cross linked phenyl silicone gum phase) was used. The separation was carried out with nitrogen as carrier gas using a detector at 523 K. Terpineol was the major component of the precipitated matter ( 65 % w/w). 

Ozonation of NjN-dimethylaniline (IVa). The amine (10 mmoles) was dissolved in methylene chloride (150 ml) and ozonized at —78°C with 10 mmoles of ozone (nitrogen as carrier gas) (12) quantitative absorption occurred. The solution became dark brown, and finally a tarry substance separated out. This substance, which adhered to the walls of the ozonation vessel, was repeatedly digested with methylene chloride. The combined methylene chloride extracts, after washing with water, were concentrated and analyzed by GLC. The results are shown in Table II. 

Ozonation of -Nitro-N N-dimethylaniline (IVc). Concentration, temperature, and solvents were varied as shown in Table II. In a typical run, 5 mmoles of amine were dissolved in 200 ml of ethyl acetate and ozonized at 0°C with 5 mmoles ozone, using nitrogen as carrier gas quantitative absorption occurred. The exit gas was analyzed for molecular oxygen. After the solution had come to room temperature, it was still clear and homogeneous. The solvent was evaporated, and the residue was dried and weighed. Ethyl acetate (200 ml) was added. A yellow compound (VII) was now insoluble and was removed by filtration. The filtrate was evaporated, and the residue was examined by PMR. The amounts of p-nitro-N,N-dimethylaniline (IVc, starting material), p-nitro-N-methylaniline (V), and p-nitro-N-methyl formanilide (VI) were esti-... 

GC analysis was performed on a Shimadzu GC-8A instrument equipped with a flame ionization detector and a capillary column of PEG-HT (0.25 x 25000 mm) using nitrogen as carrier gas. 

Li, Y.Y., Bae, S.D., Sakoda, A., Suzuki, M. (2001a), Formation of vapor grow carbon fibers with sulfuric catalyst precursors and nitrogen as carrier gas. Carbon, 39, 91-100. Li, Y.Y., Bae, S.D., Nomura, T., Sakoda, A. and Suzuki, M. (2001b), Preparation of Custom-Tailored Carbon Whisker Membrane by Chemical Vapor Deposition, in K. Kaneko (Ed.), Fundamentals of Adsorption, 7,279-286. 

Li, Y.Y., Bae, S.D., Sakoda, A. and Suzuki, M., 2001, Formation of vapor grown caibon fibers with sulfuric catalyst precursors and nitrogen as carrier gas. Carbon, 39(1), 91-100. 

Gas chromatography has been used to determine arsine in hydrogen-rich mixtures. The arsine was detected on a column containing dioctyl phthalate on polyoxyethylene-glycol as adsorbent with hydrogen as the carrier gas. The limit of detection as arsenious oxide was 0.001 mg. In addition, determinations of down to 4.2 x 10 gl of arsine in silane on various columns have been developed , using dry nitrogen as carrier gas and a... 

In a typical experiment they used trimethylgallium and ammonia as precursors with argon or nitrogen as carrier gas and maintained the deposition temperature at... 

A gas chromatographic procedure is cited in the BP for the assay econazole nitrate in a cream base". Econazole nitrate is extracted into methanol - 0.6m sulphuric acid, whilst other lipid soluble excipients are extracted into carbon tetrachloride. The aqueous extracts are made alkaline with 2 M ammonia and extracted into Chloroform. An internal standard, 1,2,3,4-tetraphenylcyclopenta-l,3-diene is added to the chloroform extracts and then evaporated to a low volume. Extracts were chromatographed on a 1.5 m x 2.0 mm OV-17 (or equivalent column) at 270°C using nitrogen as carrier gas and flame ionization detection. 

Experiments were conducted on a headspace gas chromatograph (86.10, Dani, Italy), equipped with a headspace sampler (HS 40, Perkin Elmer, Germany), and a FID detector (temperature 240 °C). Samples were equilibrated on a shaker (at 80, 100,70,90 and 80 °C for n-heptane, toluene, acetonitrile, n-propanol and 1,4-dioxane, respectively) for 1 h. The sample was automatically injected (injector temperature 130 °C) with nitrogen as carrier gas. A Hewlett Packard 25 m x 0.32 mm HP-1 0.17-pm column was used for 1,4-dioxane, toluene, n-heptane and acetonitrile, while a Varian 30 m x 0.25 mm CP WAX52CB 0.25-pm column was used for n-propanol. An isothermal programme was run for 8 min. at 80 °C. 

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