Elemental analyses

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. 

Carbon content and hydrogen content can be determined simultaneously by the method designated for coal and coke (ASTM D3178) or by the method designated for municipal solid waste (ASTM E777). However, as with any analytical method, the method chosen for the analysis may be subject to the peculiarities or character of the feedstock under investigation and should be assessed in terms of accuracy and reproducibility. There methods that are designated for elemental analysis are  

The hydrogen content of fuel oil can also be measured by low-resolution magnetic resonance spectroscopy (ASTM D3701, D4808). The method is claimed to 

Nitrogen occurs in residua, and therefore in residual fuel oil, and causes serious environmental problems as a result, especially when the levels exceed 0.5% by weight, as happens often in residua. In addition to the chemical character of the nitrogen, the amount of nitrogen in a feedstock determines the severity of the process, the hydrogen requirements, and to some extent, the sediment formation and deposition. 

The determination of nitrogen in petroleum products is performed regularly by the Kjeldahl method (ASTM D3228), the Dumas method, and the microcoulomet-ric (ASTM D3431) method. The chemiluminescence method is the most recent technique applied to nibogen analysis for petroleum and is used to determine the amount of chemically bound nitrogen in liquid samples. 

Elemental analysis involves measuring the composition of materials to determine 

The foundations of the modem science and the systematic investigation of the elements began in the Arabic world where experiments with scientific questions were well underway in the ninth-century ad. Jabir ibn Hayyan, one of the founding fathers of chemistry, was bom in Persia and a prolific scholar. He emphasized experimentation and invented a wide variety of laboratory equipment, as weU as a number of fundamental processes such as distillation and crystallization. He discovered and described many basic chemical substances - including hydrochloric and nitric acid, and the elements arsenic, antimony and bismuth - that are the basis of chemistry today. He was the first to purify and isolate sulfur and mercury as pure elements. He began to systematically describe the basic elements and provided the framework for the periodic table by distinguishing metals and nomnetals in his classification. 

The periodic table is the contribution of a Russian scientist, Dmitri Mendeleev, who organized a long list of known chemical elements into a systematic framework in 1869 with 66 known elements. Mendeleev arranged the elements by mass and other properties and predicted the existence of new elements in his table based on the repetitive patterns he observed (the periodic behavior of the elements). This table of elements has now grown to more than 100 and new discoveries continue to be made, although only 90 are naturally occurring and of potential archaeological interest. 

Carbon and hydrogen content (ASTM D-1018,ASTM D-3178, ASTM D-3343, ASTM D-3701, ASTM D-5291, ASTM E-777, IP 338)  

Nitrogen content (ASTM D-3179, ASTM D-3228, ASTM D-3431, ASTM E-148, ASTM E-258, ASTM D-5291, and ASTM E-778)  

The hydrogen content of fuel oil can also be measured by low-resolution magnetic resonance spectroscopy (ASTM D-3701, ASTM D-4808). The method is claimed to provide a simple and more precise alternative to existing test methods, specifically combustion techniques (ASTM D-5291), for determining the hydrogen content of a variety of petroleum-related materials. 

Elemental analysis of the IHSS reference material was provided by IHSS with purchase of the organic material. The elemental analysis was performed for IHSS by Huffman Laboratories (Wheat Ridge, CO, USA). Results are summarised in Table 4.5. 

The Mooney Mooney Dam NOM was also to be analysed by IHSS. However, the wet digestion method which is used for HA and FA cannot be appUed directly to NOM and is currendy being revised. The method to be developed will also analyse the ash composition. 

Elemental analysis is more important for fluorinated surfactants than for hydro-carbon-type surfactants because the fluorine content can indicate the concentration of a fluorinated surfactant in admixture with hydrocarbon-type surfactants or 

Fluorine in an organic substance can be determined by nondestructive methods or by destruction of the organic matter by combustion or fusion. Nondestructive methods include neutron activation [6] and x-ray fluorescence. Nondestructive methods for elemental fluorine analysis are rapid but require unusual equipment or are not adequately accurate, sensitive, or versatile. 

Two units are routinely used in Jackson Laboratory of Du Pont, and during their 30-year history, no serious incidents have occurred. Although the mixture of oxygen and hydrogen is potentially hazardous, elaborate safety devices, such as automatic shutdown valves built into the apparatus, assure a safe operation. 

Other versions of the oxyhydrogen torch have been developed [12]. A combustion apparatus is commercially available from Heraeus [13]. In an aspirating combustion apparatus, which draws a liquid sample directly into the oxyhydrogen flame, the sample may be swept through the flame without a complete combustion. A two-stage combustion sequence is essential for the complete conversion of organic fluorine to fluoride (1) the pyrolysis and partial combustion of the sample in the pyrolysis tube and (2) the complete breakdown of the pyrolysis products in the oxyhydrogen flame. 

Combustion in an oxygen Parr bomb [14.15], although less vigorous than combustion in a oxyhydrogen flame, has given quantitative results for perfluo-rooctanoic acid and its salts. However, the method is not suitable for volatile organic fluorine compounds. Aqueous samples (e.g., blood) have to be dried and pelletized. 

Typical results of the elemental analysis of P30T, synthesized by Grignard coupling, are shown in table 3. The iodine content can be reduced to less than 0.05% by heat treatment at about 120°C in nitrogen or vacuum [27,35]. P30T obtained by oxi tion contains significant amounts of Fe and Q (2-4%), if not washed with extreme care. 

Elemental analysis of poly(3-octylthioi ene) synthesized by the Grignard reaction. 

Quahtative and quantitative elemental analysis of polymers can be carried out by the conventional methods used for low-molecular-weight compounds. So a detailed description is not needed here. Elemental analysis or determination of functional groups is especially valuable for copolymers or chemically modified polymers. For homopolymers where the elemental analysis should agree with that of the monomer, deviations from the theoretical values are an indication of side reactions during polymerization. However, they can also sometimes be caused by inclusion or adsorption of solvent or precipitant, or, in commercial polymers, to the presence of added stabilizers. The preparation of the sample for analysis must, therefore, be very carefully carried out (several reprecipitations, if necessary using various solvent/precipitant combinations thorough drying). 

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

Taken together, these solvent-solute interactions make up the solvent polarity, which is represented well by Hildebrand s solubility parameter (1950). 

Added to these interactions are the electrostatic forces related to the dielectric constants and which are important when it is necessary to separate ionic components. 

At the column outlet, either of two detection methods are employed  

Note that in liquid phase chromatography there are no detectors that are both sensitive and universal, that is, which respond linearly to solute concentration regardless of its chemical nature. In fact, the refractometer detects all solutes but it is not very sensitive its response depends evidently on the difference in refractive indices between solvent and solute whereas absorption and UV fluorescence methods respond only to aromatics, an advantage in numerous applications. Unfortunately, their coefficient of response (in ultraviolet, absorptivity is the term used) is highly variable among individual components. 

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. 

The methods officially used in the wine trade transactions are summarized in Table 8.1. Generally, the OIV methods are officially adopted in the European Union without significant technical changes. The methods reported are mainly colorimetric, titrimetric, or use Atomic Emission Spectroscopy (AES, e.g. Flame Spectrophotometry), Atomic Absorption Spectroscopy (AAS), Hydride Generation-AAS (HG-AAS), Electrothermal-AAS (ET-AAS) and Vapour Atomic Flourescence Spectrophotometry (VAF). 

The main pros and cons of the techniques more extensively used for elemental analysis in the oenological field are shown in Table 8.2. 

Iron (MA-F-AS322-05-FER). Reference method it is quantified by AAS in the diluted and dealcoholized wine at 248.3 nm. Iron (970.19). Method I a diluted solution of wine is analyzed by AAS at 248.3 nm and the concentration is quantified in comparison with alcoholized standards. 

Usual method it is colorimetrically measured on the H202 oxidized sample after reaction with an ortophenantroline reagent. Method II the content of iron is measured after reaction with 2,4,6-tripyridyl-s-triazine with a spectrophotometer at 593 nm. 

Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) is the best compromise between costs and technical performance for winery quality control laboratories, while Inductively Coupled Plasma Mass Spectrometry (ICP-MS), because of its extreme reliability and productivity, is more widely used in research laboratories. 

Prepare an analar solution of 12 g ammonium ferric sulphate in water and add 40 ml of analar nitric acid. Dilute to 100 ml. Prepare a solution containing 0.4 g of mercuric thiocyanate crystals in 100 ml of absolute alcohol. Mix 5 ml of the test solution from the oxygen flask combustion method (described above) with the ammonium ferric sulphate solution. Add 1.5 ml of mercuric thiocyanate solution. When chlorine is present an orange to red colour will develop in the test sample. If a semi-quantitative estimation of chlorine is required, set the solution aside for 10 min, then measure the optical density of this coloured solution against the blank solution at 460 nm in 20 mm cells. Typical calibration figures for the examination of plastic coatings such as PVC are as follows  

Dissolve 0.2 g of peptone in 50 ml of 1% w/v barium chloride solution. Buffer to a pH of 5.0 with 0.02 N hydrochloric acid and add 10 g of analar sodium chloride, diluting to 100 ml. Heat in a water bath for 10 min at below boiling and add a few drops of chloroform, followed by filtration. This is solution A. Dissolve 0.4 g of gum ghatti in 200 ml of distilled water by warming. Then add 2.0 g of bariiun chloride and filter if necessary. This is solution B.. lust before use, add 10 ml of A to 100 ml of B. This is the precipitating reagent C. 

Transfer 5 ml of the above unknown test solution to a test tube and add 2 drops of 100 volume hydrogen peroxide followed by 1.2 ml of 1N HCl. Mix well and add 2.0 ml of the precipitating agent C. A distinct turbidity will be produced if sulphur is present. If a semi-quantitative estimation of sulphur content is needed, add 5 ml of distilled water to both a blank and the turbid solution, mix and leave for 30 min. 

Measure the optical density of the test solution in a 40 mm cell at 700 nm. Useful calibration figures are given below  

Weigh 0.1 g of resorcinol into a clean dry beaker and dissolve in 0.5 ml of glacial acetic acid. Add 5 ml of the test solution, mix and add 0.1 g of ammonium ferrous sulphate. Prepare a blank test solution for comparison. A green colour in the test sample, compared with a pale yellow in the blank indicates the presence of nitrogen. 

These specific instrumental analyses are found in a variety of domains such as the petrochemical industry, metallurgy, agriculture and the sectors of atmospheric pollution, soils and water sectors, the detection of chemical weapons, the fight against terrorism and other areas. These instrumentation of specific analysers should not be neglected. This chapter reviews several original methods limited to single elements only. 

Sodium fusion involves heating sodium metal or a sodium-lead alloy to a high temperature and then adding the organic compound. Use extreme care when performing both the heating and addition. 

Use a Pyrex test tube and check it for cracks or other imperfections before performing the sodium fusion. 

If pure sodium metal is used, hydrolyze the residue very carefully as directed, because any excess metal reacts v/gorousAy with alcohol or water. 

Be careful when handling the test tube after the fusion is complete remember that it may still be hot. 

Throughout this procedure, point the mouUt of the test tube away from yourself and your neighbors the organic material may burst into flame when it contacts the hot metal, or it may react so violently that hot materials are splattered from the test tube. 

Modem CHN analysers are also equipped to determine S and O compositions. Sulfur is determined by oxidation to SO2, and oxygen by conversion to CO, then to CO2. 

CH analysis of a compound [PtCl2(PR3)2] gives C 54.65, H 3.83%. Is R = Ph or Bu Are the experimental data within acceptable limits compared to the calculated 

Electronic Spin Resonance (ESR) spectra were recorded at T = 5K and at room temperature on an ESR 500 Briicker spectrophotometer working at i/ = 9.449 GHz in order to identify the local environments of Ti +. 

Thermal analyses were conducted in the temperature range 25-800 °C using two instruments (i) a Setaram SETSYS Evolution thermoanalyser and (ii) a simultaneously coupled TGA-MS device, a Netzsch STA 409C Skimmer , equipped with a Balzers QMG 421 and a Pulse TA unit.  

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Fractionation and Elemental Analysis of Crude Oils and Petroleum Cuts... 

Crude oils form a continuum of chemical species from gas to the heaviest components made up of asphaltenes it is evidently out of the question, given the complexity of the mixtures, to analyze them completely. In this chapter we will introduce the techniques of fractionation used in the characterization of petroieum as well as the techniques of elemental analysis applied to the fractions obtained. 

Chapter 2. FrACTIONAVON AND ELEMENTAL ANALYSIS OF CRUDE OILS AND PETROLEUM CUTS... 

Although distillation and elemental analysis of the fractions provide a good evaluation of the qualities of a crude oil, they are nevertheless insufficient. Indeed, the numerous uses of petroleum demand a detailed molecular analysis. This is true for all distillation fractions, certain crude oils being valued essentially for their light fractions used in motor fuels, others because they make quality lubricating oils and still others because they make excellent base stocks for paving asphalt. 

Thus the quantitative elemental analysis of the fuel establishes an overall formula, (CH O ) , where the coefficient x, related to the average molecular weight, has no effect on the fuel-air ratio. 

Elemental Analysis Atomic absorption spectrometry X-Ray fluorescence spectrometry Plasma emission spectrometry... 

Scattering and recoiling contribute to our knowledge of surface science tln-ough (i) elemental analysis, (ii) structural analysis and (iii) analysis of electron exchange probabilities. We will consider the merits of each of these tluee areas. 

Johanssen S A E and Campbeii J L 1988 FIXE A Novel Technique for Elemental Analysis (Chichester Wiiey) Covers PiXE in detaii and is a good reference for graduate students and researchers. 

Because model colloids tend to have a ratlier well defined chemical composition, elemental analysis can be used to obtain detailed infonnation, such as tlie grafted amount of polymer in tire case of sterically stabilized particles. More details about tire chemical stmcture can be obtained using NMR techniques (section B1.13). In addition, NMR... 

Pittman, J. F.T. and Nakazawa, S., 1984. Finite element analysis of polymer processing operations. In Pittman, J.F. T., Zienkiewicz, O.C., Wood, R.D. and Alexander, J. M. (eds), Num,erical Analysis of Forming Processes, Wiley, Chichester. 

Pittman, J.F.T. and Nakazawa, S., 1984. Finite element analysis of polymer processing... 

Kheshgi, H. S. and Scriven, L. E., 1985. Variable penalty method for finite element analysis of incompressible flow. Int. J. Numer. Methods Fluids 5, 785-803. 

Ghassemieli, E. and Nassehi, V., 2001c. Prediction of failure and fracture mechanisms of polymeric composites using finite element analysis. Part 2 liber reintorced composites. Poly. Compos. 22, 542-554. 

Nassehi, V. and Ghoreishy, M, H. R., 1998. Finite element analysis of mixing in partially filled twin blade internal mixers. Int. Polym. Process. XIII, 231 -238. 

The most frequently used modifications of the basic Gaussian elimination method in finite element analysis are the LU decomposition and frontal solution techniques. 

Irons, B, M., 1970. A frontal solution for finite element analysis, hit. J. Numer. Methods Eng. 2, 5-32,... 

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