Carbon-nitrogen ratios elemental analyses

If the sample is pure (this can generally be checked by thin layer chromatography or gas chromatography) then the elemental analysis values for carbon, hydrogen and nitrogen can be used to obtain element ratios, provided that C, H, N and 0 are the only elements present. 

Elemental analysis of fuel oil often plays a more major role that it may appear to do in lower-boiling products. Aromaticity (through the atomic hydrogen/carbon ratio), sulfur content, nitrogen content, oxygen content, and metals content are all important features that can influence the use of residual fuel oil. 

J 5). Average analytical variability of sample preparation and stable carbon isotope ratio analysis is +0.2 (1 ). A Carlo-Erba Model 1106 Elemental Analyzer was employed to determine percent organic carbon and nitrogen in each sediment sample. Analytical variation of sample analysis is 20 (17). 

In a similar fashion, quantitative elemental analysis for carbon, hydrogen, nitrogen, and oxygen enabled the chemist to determine the empirical formulas of organic compounds. An empirical formula is the simplest whole number ratio of the atoms of each element present in a molecule. For any given compound, the empirical formula may or... 

Elemental analysis includes carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur, halogen, and elemental ratios C/H, 0/C, and C/N. Typical elemental composition of water and soil humic substances are shown in Table 1. Carbon is the major element and it... 

Like BSIA, two sample conversion systems are required depending on the element/s of interest. For example, Thermo Fisher Scientiflc (Waltham, MA) supplies a GC Combustion III (CIII) interface system for the preparation of samples for nitrogen and carbon isotope ratio measurements. They also have a High Temperature Conversion (TC) interface system for sample preparation for hydrogen and oxygen analysis [1,36,37]. 

The combination of gas chromatography and an isotope ratio measurement mass spectrometer (ir/n-GC-MS) was used to study the detoxification and degradation pathways of tropane alkaloids involving iV-demethylation to the respective nor-compounds. Molinie et al. developed protocols for sample preparation, including liquid-hquid and SPE extraction, and analysis of the kinetic isotope effects (KlEs) with irm-GC-MS and ir/M-elemental analysis (EA)-MS [100]. Degradation experiments were performed with a Pseudomonas strain that uses tropane alkaloids as sole source of carbon and nitrogen. The authors found that liquid-liquid extraction from the aqueous medium in combination with ir/n-GC-MS was the most convenient method for measurement of the ratio. Later, Kosieradzka... 

Faraday also heated the rubber in an anaerobic distillation apparatus, as described in Murray s account. A group of volatile substances were isolated. He was able to show that caoutchouc is a pure hydrocarbon, with no traces of oxygen or nitrogen. Elemental analysis yielded a C/H ratio of 8/7 in early nineteenth century practice. (Carbon was then treated as M = 6, rather than 12, with H as 1). Modem values are represented by the empirical formula CsHg. 

Cellulose(CEL)- and polyacrylonitrile(PAN)-based ACF s and coconut-shell granular activated carbons (AC) were used in this study. Also nonporous carbon black(NPC) whose surface area Is 81 m g" was examined by in situ XRD for comparison. The adsorption Isotherms of water at 298 K and N2 at 77 K on samples were measured gravimetrically. The ACF sample was pre-evacuated at 383 K and 1 mPa for 15 h prior to the adsorption. The evolved gas analyses (EGA) of ACF samples preheated at 373 K under 1 mPa for 15 h were carried out at a heating rate of 10 K min with the aid of a mass filter(ULVAC, MSQ-150A). The elemental analysis for the nitrogen atom of the ACF samples was done the ratios of nitrogen to carbon in wt. % of CEL and PAN were 2 and 6-7, respectively. 

In recent years, tremendous progress has been achieved in the analysis of the isotope composition of important trace compounds in the atmosphere. The major elements - nitrogen, oxygen, carbon - continually break apart and recombine in a multitude of photochemical reactions, which have the potential to produce isotope fractionations (Kaye 1987). Isotope analysis is increasingly employed in studies of the cycles of atmospheric trace gases e.g., CH4 and N2O, which can give insights into sources and sinks and transport processes of these compounds. The rationale is that various sources have characteristic isotope ratios and that sink processes are accompanied by isotope fractionation. 

The analysis of petroleum feedstocks for the percentages of carbon, hydrogen, nitrogen, oxygen, and sulfur is perhaps the first method used to examine the general nature, and perform an evaluation, of a feedstock. The atomic ratios of the various elements to carbon (i.e., H/C, N/C, O/C, and S/C) are frequently used for indications of the overall character of the feedstock. It is also of value to determine the amounts of trace elements, such as vanadium and nickel, in a feedstock since these materials can have serious deleterious effects on catalyst performance during refining by catalytic processes. 

Minor element contents and isotopic ratios are used for physiological purposes. Sr/Ca ratios in bone and teeth are said to reflect the diet of the animal (herbivores versus carnivores). Stable isotope analysis of teeth and bones provides direct information on the lifetime diets the nitrogen isotopes reflect the trophic level of the protein that has been consumed. Within an ecosystem, they can identify herbivores and carnivores, while the carbon isotopes tell mainly about the amount of protein in the diets from terrestrial versus marine ecosystems. 

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