Simultaneous Determination Of Carbon Research Articles

Rapid and Simultaneous Determination of Carbon, Hydrogen, Nitrogen and Sulfur in Flame Returdant Organic Compounds by Contact Vapor Phase Oxidation

Rapid and Simultaneous Determination of Carbon, Hydrogen, Nitrogen and Sulfur in Flame Returdant Organic Compounds by Contact Vapor Phase Oxidation

A standardized method for the determination of the intrinsic carbon and nitrogen mineralization capacity of natural organic matter sources

A new method was developed for the simultaneous determination of the intrinsic carbon and nitrogen mineralization capacity of organic matter (OM) sources by means of an aerobic incubation in suspension. The proposed method is based on determination of the oxygen consumption, monitored indirectly via pressure measurement, and on determination of nitrogen mineralization, through the periodical measurement of NH 4 +-N, in a liquid suspension of the samples. The suspension is standardized in terms of nutrient composition and pH, and well-controlled incubation conditions that can be enforced as desired. This method rules out the effect of soil conditions and thus reflects the intrinsic properties of the OM. The method is faster and more reproducible than soil incubation tests that are currently used. In such a system, it is important that nitrification is inhibited to avoid oxygen consumption by nitrifiers and prevent the production of gaseous nitrogen compounds. Two nitrification inhibitors, N-allylthiourea and 2-ethynylpyridine, were tested at different concentrations for three reference samples, soil, bark and manure. Both inhibitors completely suppress NO 3 − formation without suppressing the heterotrophic microbial activity, thus allowing the correct determination of the oxygen uptake rate (OUR). When nitrification inhibitors were added, nitrous oxide could not be detected anymore in the gas phase of the system, which confirms that nitrification was inhibited and indicates that denitrification and nitrifier denitrification activity was negligible. N mineralization rates were determined by frequent sampling from the liquid phase of the system without disturbing the pressure measurement during the incubation and subsequent determination of NH 4 +-N. The method presented allows for the reliable and relatively easy and cheap, simultaneous determination of carbon and nitrogen mineralization rates for a wide range of OM sources.

Simultaneous determination of carbon, hydrogen, and nitrogen in solid lubricating coatings

Simultaneous determination of carbon, hydrogen, and nitrogen in solid lubricating coatings

Simultaneous determination of carbon and sulphur in geological material, using inductive combustion

The simultaneous determination of sulphur and total carbon in 0.1–0.5 g samples of geological material has been achieved, using a Leco ® induction furnace with slight modifications to conventional attachments. The analyses are accomplished by initial removal of sulphur dioxide by absorption and titration, followed by collection of carbon dioxide in a gravimetric absorber. Accuracy and precision are similar to established individual combustion techniques and high levels of sulphur do not interfere with the carbon determination. Total analysis time is reduced considerably and the lifetime of some absorption components is extended.

Investigations of oxidizing additives in flash combustion of organic chlorine compounds

The suitability of V2O5 and Co3O4 deposited on porous silica as the combustion aids for flash combustion of organic chlorine compounds has been studied. The chlorine recovery as a function of sweep-out time with a stream of dry or moist oxygen was determined. Quantitative removal of chlorine from a tube inca. 10 min can be achieved only with a stream of moist oxygen. Combustion in a stream of moist oxygen in the presence of Co3O4 precludes final gravimetric determination of chlorine by binding it on metallic silver, because the capacity of the silver for reaction with chlorine in the form of HCl rapidly decreases, falling to about 30% of the initial value after only 5 determinations. Iodogravimetric determination of the chlorine yields correct results and allows simultaneous determination of carbon, for samples up to 45 mg.

Automatic microanalysers?V

Following the O-analyser, CH-analyser and N-analyser previously developed, an automatic CHN-analyser is described, based on the principle already used by Walisch. It involves a flash combustion of the sample in a stream of helium with 3% oxygen content, in a vertical reactor, the reduction of nitrogen oxides and removal of excess of oxygen by reduced copper, and the measurement of carbon dioxide, nitrogen and water by a thermal-conductivity cell. The signal from the detector is automatically integrated as a function of time and printed out. The analyser has been fully automated by the use of a vertical reactor, an automatic sample feeder and a collecting tube. This analyser makes possible the simultaneous determination of carbon, hydrogen and nitrogen in stable or unstable solid and liquid organic compounds within 13 min. The precision of results for sample weights in the range 0.2–0.5 mg has been shown to be equivalent to that obtained by Walisch.

Simultaneous determination of carbon, hydrogen and fluorine in fluoro-organic compounds

Simultaneous determination of carbon, hydrogen and fluorine in fluoro-organic compounds

Simultaneous determination of carbon, hydrogen, and silicon in organosilicon compounds

A simple method is described for the simultaneous microdetermination of carbon, hydrogen, and silicon in organosilicon compounds containing C, H, O, N, Si, and halogen. The method ensures reliable and accurate results.

The simultaneous determination of carbon and oxygen in electroplated gold by helium-3 activation

The carbon and oxygen contents in several types of hard electroplated gold and one type of soft gold plate have been determined by helium-3 activation analysis. The results for carbon are in the same range as those obtained from combustion analyses on similar samples. The carbon-to-oxygen ratio was found to vary from 2.5 to about 4 for hard gold plates. The maximum bulk level of carbon and oxygen in a soft gold electroplate was found to be about 10 -2 atom- %. The technique requires no chemical separations and can easily detect impurities at the p.p.m. level.

Microdetermination of carbon, hydrogen, and selenium in organic compounds

1. A method was developed for the simultaneous determination of carbon, hydrogen, and selenium by the pyrolytic decomposition of the substance in an empty tube, with the absorption of selenium oxide by electrolytically deposited silver at 480°. 2. The method is applicable for the analysis of compounds containing, besides selenium, also sulfur or sulfur and halogen. In such cases the amount of selenium, sulfur, and halogen is determined by calculation from the weight increase of the silver.

Simultaneous determination of carbon, hydrogen, and nitrogen by means of gas chromatography

The method described of elemental analysis of carbon, hydrogen, and nitrogen is based on the oxidation pyrolysis of sample in a tube containing Dumas filling; dilution of the combustion products with helium in a cylindrical chamber with pneumatically controlled piston; setting of the diffusional equilibrium at constant state conditions in the chamber; chromatographic separation of the nitrogen, carbon dioxide, and water by the frontal technique; and detection of the above substances by a katharometer. Two records, those of sorption and desorption, are obtained from a single sample. The use of both records makes it possible to decrease considerably the error of determination, brought about by the Chromatographic, detection, and recording parts of the instrument. The expanding of the detector signal over several recorder scales is used to an advantage. The method provides for the combustion under both static and dynamic conditions, as well as work on submicro-, micro-, and, if need be, semimicroscales.

Lead dioxide in simultaneous microdetermination of carbon, hydrogen and halogens or sulphur

The use of lead dioxide as the internal absorbent for all substances which usually interfere in organic microanalysis is described. It has been found that at room temperature lead dioxide absorbs sulphur (as SO2) and halogens. Because of this property lead dioxide can be successfully used as external absorbent in simultaneous determination of carbon, hydrogen and sulphur or halogens in compounds not containing nitrogen.

Method of decomposing an organic substance with simultaneous determination of carbon, hydrogen, and nitrogen by the method of gas chromatography

1. The advantage of the oxidation of organic substances in a static system (closed volume) over the dynamic (jet) method was demonstrated. In a closed volume profound pyrolysis, repeated and as prolonged contact of the decomposition products with the oxidizing agent as desired, and continuity of the oxidation process can be guaranteed. The time of contact of the substance with the oxidizing agent is regulated by the analyst. 2. The rate of oxidation in a closed volume depends on the oxidizing agent used, its physicochemical properties.

Absorbents in microanalysis. II

The use of silica gel as the external absorbent for halogens and sulphur and nitrogen oxides in the microanalytical determination of carbon and hydrogen is described. As the chlorine is bound quantitatively the procedure is useful in simultaneous determination of carbon, hydrogen and chlorine.

Method of decomposition of an organic substance with simultaneous determination of carbon, hydrogen, and nitrogen by the gas chromatography method

1. The completeness of the oxidation of an organic substance by oxides in a flow-type system depends not only upon the effectiveness of the oxidizing agent, but also upon the rate of delivery of the substance to the oxidizing layer and upon the physical and chemical properties of the substance. In the classical method of decomposition of the sample, identical conditions guaranteeing an equal degree of oxidation of various substances cannot be ensured. 2. In decomposition in a semiclosed system (with delivery of the products of thermal decomposition of the substance to the oxygen-rich zone), complete oxidation of the organic substance is ensured independent of the use of an oxidizing agent. 3. When the oxidation was conducted in an inert gas atmosphere, nickel oxide proved to be the most active of the tested oxidizing agents.

Elemental analysis of organo-metallic compounds: The simultaneous determination of carbon, hydrogen and other elements in one weighed sample

A method is described for simultaneous gravimetric microdetermination of carbon, hydrogen and one or more heteroelements in one weighed sample of organic substances. The method is based on pyrolytic combustion of the sample in a quartz container placed in an empty combustion tube. The carbon and hydrogen determination is completed as usual. Hetero-elements, in the form of volatile compounds, are retained in special previously weighed tubes inside the combustion tube. Hetero-elements forming non-volatile residues can be determined by the change in weight of the quartz sample-container. Volatile elements or compounds are determined by weighing the quartz insert tube. More than 40 elements in various combinations can be determined simultaneously with carbon and hydrogen.

Simultaneous Determination of Carbon and Sulfur in Steels by Combustion at Low Temperature.

Simultaneous Determination of Carbon and Sulfur in Steels by Combustion at Low Temperature.

The handling of volatile compounds for the simultaneous determination of carbon, hydrogen, and nitrogen

A technique is described, which permits obtaining the correct weight of a volatile substance, vapor pressure not exceeding four atmospheres at ambient temperature, previous to combustion in a vacuum system.

Rapid multiple microdetermination of carbon and hydrogen

A technique has been developed for the simultaneous determination of carbon and hydrogen in at least four independent samples. A largediameter furnace and small combustion tubes make it possible to position at least four combustion tubes in the furnace at one time. An operator can analyze eight samples in one hour (7 1/2 minutes per analysis). The low cost of the apparatus and the relatively small amount of bench space needed make this technique especially advantageous for low-budget industrial, governmental, and academic laboratories.

Simultaneous Determination of Carbon, Hydrogen, and Nitrogen at the Decimilligram Level.

Simultaneous Determination of Carbon, Hydrogen, and Nitrogen at the Decimilligram Level.