Combustion elemental analysis

Kjeldahl method Combustion elemental analysis Volumetry (titrimetry) Chromatography Gravimetry... 

Table 8.4 Decomposition methods for elemental analysis Combustion ...

Combustion (elemental) analysis of polymeric supports has mainly been used to determine the amount of halogens, nitrogen, or sulfur present in samples of cross-linked polystyrene (see, e.g., [54]). This information can be used to estimate the loading of a support, or, for example, to verify that the displacement of a halide has proceeded to completion. In solid-phase peptide synthesis, nitrogen determination has been used to estimate the loading of the first amino acid [55]. 

Combustion of coal produces ash that can be transported through the air. Slagging and fouling problems can also be predicted from elemental analysis. Therefore, elemental analysis of both the coal as well as the ash are important. Procedures for dissolution and analysis of coal and combustion products of coal have been reported [334-336]. Laser ablation sampling has been successfully used for coal and combusted materials [337,338]. The direct introduction of slurries has also been used [339]. Comparison of ICP-MS and PIXE analysis of coal combustion aerosols showed that analysis errors can occur in ICP-MS if particle vaporization is incomplete in the ICP [340]. 

Sentences are often found meaning explicitly or implicitly 5 ppm accuracy is sufficient to deduce the elemental composition . This is absolutely not true and is at the origin of many exaggerations. This value comes from a rule of the American Chemical Society that states For most new compounds, HRMS data accurate within 5 ppm or combustion elemental analysis accurate within 0.4% should be reported to support the molecular formula assignment [11]. Thus, this rule does not tell that 5ppm accuracy can be used to deduce an elemental composition, but that it can be used in support of a proposed formula, but not as a proof of that formula. 

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. 

Fig. 13 Dependence of the total carbon content (yc) of the PVFA-co-PBVU/silica hydrogels on the initial BVU content of the reaction mixture (xbvu)- The carbon content was determined by combustion elemental micro-analysis...

Quantitative analysis of elements by ICP-AES and Flash-combustion GC for the 10 wt% Zr02/Si02 subjected to gaseous SO3 and for the conventional H2S04/Zr02 catalysts. Residual atom... 

ISO 13878 1998 Soil quality - Determination of total nitrogen content by dry combustion ( elemental analysis ). 

CE capillary electrophoresis CEA combustion elemental analysis CEC capillary electrochromatography cerebellum small posterior part of the brain controls coordination of voluntary movement... 

Elemental analysis is used for determination of the loading of different resins, such as amino-, bromo-, chloro-, and sulfo-resins, from the N, Br, Cl, and S contents, respectively. An accurate weight of resin is submitted for elemental analysis. Combustion of the sample provides the various elements present in the sample. The substitution level of the resin is calculated as follows ... 

KEYWORDS fluorine, fluorine, fluoride, ion-selective electrode, fuel analysis, oxidative combustion, elemental analysis... 

One of the first steps in determining the molecular structure of a compound is to establish the compound s molecular formula. In the past, this was most commonly done by elemental analysis, combustion to determine the percent composition, and so forth. More commonly today, we determine molecular weight and molecular formula by a technique known as mass spectrometry (an explanation of the technique is beyond the scope of this book). In the examples that follow, we assume that the molecular formula of any unknown compound has already been determined, and we proceed from there, using spectral analysis to determine a structural formula. 

Standard compounds have the same structures as QC compounds and are synthesized separately and purified by reversed-phase and normal-phase high-performance liquid chromatography (HPLC). After purification, standard compounds are rigorously characterized by H- and C-nuclear magnetic resonance (NMR) and LC-MS and their purity established as > 99.6% by combustion elemental analysis. 

General methods for the certification of RMs for elemental content are based on atomic absorption spectrometry (FAAS, ETAAS, HG-AAS, CV-AAS), atomic emission spectrometry (FAES, ICP-AES, HG-ICP-AES, DCP-AES), atomic fluorescence spectrometry (CV-AFS), mass spectrometry (IDMS, SSMS, NAMS, ICP-MS), nuclear methods (IPAA, PAA, INAA, RNAA), X-ray emission (EDXRF, WDXRF, particie induced techniques), light-absorption spectrometry (LAS, FL), electrochemistry (ASV, CSV, DPP, ISE) and other methods (Kjeldahl, combustion elemental analysis, volumetry, chromatography, gravimetry) [32]. Certification of BCR-680/681 was carried out by sixteen participating laboratories using a variety of common as well as highly specialised techniques (Table 8.10). 

Perini, F., Brakora, L.J., Reitz, D.R., Cantore, G. Development of reduced and optimized reaction mechanisms based on genetic algorithms and element flux analysis. Combust. Flame 159,103-119(2012)... 

In this chapter on bomb calorimetry, possible applications from different biological fields have been presented, sometimes in competition with other methods such as analysis of elemental or chemical composition (carbohydrates, proteins, lipids) and the degree of reductance. In many cases it may depend upon the facilities of an investigator or an institute which approach is chosen or thought to be "more simple". Instead of expressing a personal considered opinion about the value of combustion calorimetry compared to other techniques, citations shall be presented from a few of the papers discussed in the preceding pages. 

Chemical Composition. Chemical compositional data iaclude proximate and ultimate analyses, measures of aromaticity and reactivity, elemental composition of ash, and trace metal compositions of fuel and ash. All of these characteristics impact the combustion processes associated with wastes as fuels. Table 4 presents an analysis of a variety of wood-waste fuels these energy sources have modest energy contents. 

PicArsn FRL Res Engr Lgbk 761-146 (1973) 56) S.I. Morrow, Microscopical Combustion Studies of Nitrocellulose Thin Films in Pres surized Capillary Tubes , Microscope 22, 229— 241 (1973) 57) Anon, Element Analysis of... 

Useful information such as the functionality and crystallinity of the polymers can be obtained by using infrared spectroscopy. Elemental analysis is also considered as one of die tools for die characterization of die polymers. Due to die endgroups and incomplete combustion of the carbon, it is common to observe die low-value carbon content than die theoretical one. 

M.15 In addition to determining elemental composition of pure unknown compounds, combustion analysis can be used to determine the purity of known compounds. A sample of 2-naphthol, C)0H7OH, which is used to prepare antioxidants to incorporate into synthetic rubber, was found to be contaminated with a small amount of LiBr. The combustion analysis of this sample gave the following results 77.48% C and 5.20% H. Assuming that the only species present are 2-naphthol and I.iBr, calculate the percentage purity by mass of the sample. 

Compounds that do not decompose cleanly into their elements must be analyzed by other means. Combustion analysis is particularly useful for determining the empirical formulas of carbon-containing compounds. In combustion analysis, an accurately known mass of a compound is burned in a stream of oxygen gas. The conditions are carefully controlled so that all of the carbon in the sample is converted to carbon dioxide, and all of the hydrogen is converted to water. Certain other elements present in the sample are also converted to their oxides. 

This flowchart summarizes the method for using combustion analysis to determine the empirical formula of a compound that contains no elements other than C, H, and O. 

---