Carbon elementary analysis

Carbon elementary analysis on noncarbon-containing minerals such as synthetic Ti02 is a very helpful method to determine the carbon content introduced by a silane surface treatment. 

The quantatitive determination of the elements in an organic substance is known as elementary analysis. In this process carbon and hydrogen are determined simultaneously, whilst a separate analysis must be carried out for the determination of each of the other elements. 

Two U-tubcs containing soda-lime in the limb on the side of the flask and calcium chloride in the other limb (or the ordinary Geissler bulbs used in elementary analysis), to absorb the carbon dioxide set free in the reaction. 

Preparation of 3-hydroxy-l,3,5(10)-estratriene-17p-monobromoacetate. 10 g of l,3,5(10)-estratriene-3,17p-diol was dissolved in 400 ml of anhydrous tetrahydrofuran (THF), and then, 8.8 g of pyridine was added. A solution of 22.5 g of monobromoacetyl bromide in 74 g of carbon tetrachloride was added dropwise to the resulting solution at about -5°C to -7°C. The mixture was kept for one night. After the reaction, the resulting precipitate was separated by a filtration. The solvent was distilled off from the filtrate. The residue was dissolved in ether and recrystallized from ether to obtain l,3,5(10)-estratriene-3,17p-bis(monobromoacetate). 2 g of the product was dissolved in 900 ml of methanol and the solution was cooled to -5°C. A solution of 0.24 g of K2C03 in 20 ml of water was added dropwise to the resulting solution. After the reaction for 30 minutes, 1000 ml of water was added and the resulting precipitate was separated and dried. It was confirmed that the product was 3-hydroxy-l,3,5(10)-estradiene-17p-monobromoacetate by the elementary analysis and the IR spectrum. 

Dilute with ether (30 mL), wash successively with saturated aqueous sodium thiosulfate solution (2 x 20 mL), saturated aqueous potassium carbonate solution (10 mL), and brine (2 x 20 mL). Dry over MgSO, filter, and concentrate under reduced pressure. Purify the crude residue obtained after evaporation of the solvent by flash chromatography (hexanes ether, 4 1) to afford the desired product (0.63 g, 50% overall). Characterize the product by 1H NMR, 13C NMR, IR spectroscopy, mass spectrometry, and elementary analysis. 

Still deactivation of the catalyst with time on stream (TOS) can be observed. This deactivation is mainly due to the adsorption of dodecene and heavy products on the catalyst which block its active sites for further reaction. Elementary analysis of the catalyst after the reaction has been carried out, and a significant increase of the carbon content was found. This confirms that the deactivation of the catalyst is due to strong adsorption of organic materials on the surface of the catalyst. 

Elementary analysis of B substance (G4) showed 41% carbon, 6.6% hydrogen, 5.7% nitrogen, and 7% acetyl. The same sugars and amino sugars were again found, including 17.9% fucose, as well as the same 11 amino acids. However, content of hexosamine was lower (20-22% only) as compared to 33-37% in blood group substances A, H, and Le. ... 

Elementary analysis measurements were carried out on an automatic CHN-analyser (Perkin-Elmer 2400, USA). The chlorine content was determined by AgNOj titration. The exact amount of carbon and chlorine residues in the catalysts was determined from three independent measurements. 

As demonstrated by elementary analysis, the chlorine and carbon content of the reduced catalyst is lower compared to non-reduced catalysts. It is supposed that the chemical reduction procedure in connection with catalysts washing is highly efficient in removing the remaining carbon and chlorine residues from catalysts. Most probably, the chemical reduction decreased the chlorine content and washing of the catalysts decreased the carbon content. 

ISO 10694 (1995) Soil quality — Chemical methods — Determination of organic and total carbon after dry combustion (elementary analysis) (BS 7755-3.8 1995). 

The determination by a wet process is performed by oxidizing organic carbon with an oxidizing agent (with Mn(VII), Cr(VI), Ce(IV)) in the presence of sulphuric acid. The amount of carbon oxidized is ascertained either from the amount of CO2 obtained (as for the elementary analysis) or from the amount of the oxidizing agent consumed during the analysis. 

Samples of various stoichiometries were prepared by sintering mixtures of the hydrides and graphite in the appropriate ratios under vacuum ca. 10 bar) at 1673 K. Determination of carbon (combustion), oxygen and nitrogen (reducing fusion under He), as well as phase analysis (X-ray diffraction and metallography) are mentioned, but no details were given. Elementary analysis indicated metallic impurities in amoimts smaller than 300 parts per million. 

The catalysts before and after reaction were characterized by elementary analysis and BET apparatus to examine the alteration of the physicochemical properties of chromium oxide catalysts. Table 1 summarizes Cr and carbon contents and BET surface areas of the catalysts. The Cr content on the catalyst surface which exhibited stable removal activity at 30 ppm of the feed concentration was not changed after reaction, while that of the catalysts... 

An elementary analysis of the obtained samples showed, fliat the ratio of the elements Zn/P is equal to 3/2 that confirms the formation exactly of zinc phosphate. At the same time, in samples 2 and 3 it was discovered, respectively, 1.1 and 2.3% of carbon this points on the formation of polymeric film on the surface of nanoplates. Higher content of the carbon in sample M 3 can be explained both by the increase of the specific surface of the pigment at fire stabilization of zinc phosphate nanoplates by butylmethacrylate and by the formation of more compact polymeric film, than in a case of the stabilization with the use of BA. 

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