Analysis of Carbon, Hydrogen and Nitrogen

Chapter 2. FRACTIONATION AND ELEMENTAL ANALYSIS OF CRUDE OLS AND PETROLEUM CUTS 

Other methods for analyzing combustion products can be substituted for chromatography. Gravimetry can be used, for example, after a series of absorption on different beds, as in the case of water absorption in magnesium perchlorate or CO2 in soda lime infra-red spectrometry can be used for the detection of CO2 and water. 

The acceptable limits of this kind of analysis are shown in Table 2.2. 

The sample is burned in oxygen at 1000°C. Nitrogen oxide, NO, is formed and transformed into NO2 by ozone, the NO2 thus formed being in an excited state NO. The return to the normal state of the molecule is accompanied by the emission of photons which are detected by photometry. This type of apparatus is very common today and is capable of reaching detectable limits of about 0.5 ppm. 

Chapter 2. FrACVONATION AND ELEMENTAL ANALYSIS OF CRUDE OlLS AND PETROLEUM CuTS 

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Automatic systems have been developed and are largely used in the simultaneous analysis of carbon, hydrogen, and nitrogen. Samples (up to 20) of 50-100 mg are burned and the evolved gases, CO2,... 

A test method (ASTM D5291) is available for simultaneous determination of carbon, hydrogen, and nitrogen in petroleum products and lubricants. There are at least three instrumental techniques available for this analysis, each based on different chemical principles. However, all involve sample combustion, components separation, and final detection. 

Elemental Analysis The carbon, hydrogen, and nitrogen contents of reference standards may be determined by combustion analysis. Combustion analysis thus provides an orthogonal determination of the molecular formula and the purity of the reference standard. Poor agreement between the theoretical and experimental elemental compositions is generally an indication of an impure substance or a discrepancy between the theoretical and actual molecular formulas. Elemental analysis may also identify the presence of solvates and inorganic contaminants. Elemental analysis is typically performed in specialized laboratories under blinded conditions. 

The identity of indapamide can also be determined by an elemental weight percent determination of carbon, hydrogen and nitrogen. The elemental analysis of an indapamide sample is performed and the results are compared to the following theoretical values (12). 

For inorganic and organic compounds the most common analysis undertaken is the determination of the amounts of carbon, hydrogen and nitrogen present. The usual method used is known as combustion analysis, where an accurately weighed amount of the compound is burnt in oxygen to form CO2, H2O, and N2 respectively. 

The GC method is also being applied to the elementary analysis of carbon, hydrogen, oxygen, nitrogen, sulfur, and halogen organic compounds. This permits shorter... 

This recrystallised acid is pure in the norm y accepted sense of the word, namely it has a sharp m.p. and gives on analysis excellent values for carbon, hydrogen and nitrogen. If however it is subjected to one-dimensional paper chromatography (p. 53), the presence of traces of unchanged anthranilic acid can be detected, and repeated recrystallisation is necessary to remove these traces. 

Coniine, a toxic substance isolated from poison hemlock, contains only carbon, hydrogen, and nitrogen. Combustion analysis of a 5.024 mg sample yields 13.90 mg of C02 and 6.048 mg of H20. What is the empirical formula of coniine ... 

In organic compounds, the elements ordinarily determined by what is termed ultimate analysis are carbon, hydrogen, oxygen, nitrogen, sulphur and one of the halogens. Other elements may sometimes be present but we shall not consider their determination here. 

A qualitative analysis of papaverine, one of the alkaloids in opium, showed carbon, hydrogen, and nitrogen. A quantitative analysis gave 70,8% carbon, 6.2%. hydrogen, and 4.1% nitrogen. Calculate the empirical formula of papaverine. 

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