Identification and Compositional Analysis

The following older, well-established methods based on the estimation of the selected functional groups or calculation of oil or fat contents are still used to differentiate oils or fats. However, more accurate and fast ana-l5dical methods, such as gas chromatography of fatty acids and the HPLC of triglycerides have reduced the significance of these older methods. 

Saponification number (SN). This is the weight of KOH (in mg) needed to hydrolyze a 1-g sample of an oil or fat. The higher the SN, the lower the average molecular weight of the fatty acid in the triglycerides. Some SN of various oils and fats are presented in Table 4.12 [2]. 

TABLE 4.12 Iodine (IN) and Saponification Numbers (SN) of Various Edible Fats and Oils 

Acid value (AV). This value is important for determination of free fatty acids (FFA) in crude and refined oils and fats. It is the number of milligrams of KOH needed to neutralize the organic acids present in 1 g of oil or fat. FFA is calculated as free oleic acid and reported as a percentage. The AV is determined by multipl5dng percent FFA with a factor of 1.99. 

Iodine value (IN). This value measures the unsaturation of the oils and fats in terms of the number of grams of iodine absorbed per 100-g sample. The method is applicable to all normal oils and fats not containing conjugated systems. Some IN of various oils and fats are presented in Table 4.12. 

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A TGA curve has limited ability to identify the sample or determine its composition if its nature is unknown. However, there are still many unique analytical applications based on TGA. Two primary applications are qualitative identification and compositional analysis. 

Wide-angle X-ray scattering techniques can provide direct information on key features such as crystallinity, preferred orientation, phase identification and compositional analysis.. zfs jjoj-g detailed analysis can yield details of local chain conformations and packing arrangements in both crystalline and disordered polymers. ... 

These are semisolid or solid substances formed in nature from crude oils after the volatile components have evaporated and the remainder has undergone oxidation and polymerization. They are also referred to as bitumens, waxes, and pitch. These materials are believed to consist of mixtures of complex organic molecules of high molecular weight. As with crude oils, which contain thousands of different chemical compounds, an exact chemical analysis for identification and composition is impractical to perform on the solid deposits of petroleum. 

It is quite clear from Schemes 2.1-2.5 that in rubbers polymer identification and additive analysis are highly interlinked. This is at variance to procedures used in polymer/additive analysis. The methods for qualitative and quantitative analysis of the composition of rubber products are detailed in ASTM D 297 Rubber Products-Chemical Analysis [39]. 

Applications Applications of SEC-FTIR include quantitative analysis of copolymers [701] product deformulation of hot melt adhesives characterisation of polymer compositional heterogeneity analysis of complex mixtures of urethane oligomers and eventually also the identification and quantitative analysis of polymer additives... 

Caputo, B., Dani, F. R Home, G. L Petrarca, V., Turillazzi, S., Coluzzi, M., Priestman, A. A. and della Torre, A. (2005). Identification and composition of cuticular hydrocarbons of the major Afrotropical malaria vector Anopheles gambiae s.s. (Diptera Culicidae) analysis of sexual dimorphism and age-related changes. 

Instrumental Analysis. It is difficult to distiaguish between the various acryhcs and modacryhcs. Elemental analysis may be the most effective method of identification. Specific compositional data can be gained by determining the percentages of C, N, O, H, S, Br, Cl, Na, and K. In addition the levels of many comonomers can be estabhshed usiag ir and uv spectroscopy. Also, manufacturers like to be able to identify their own products to certify, for example, that a defective fiber is not a competitor s. To facihtate this some manufacturers iatroduce a trace of an unusual element as a built-ia label. 

The physical techniques used in IC analysis all employ some type of primary analytical beam to irradiate a substrate and interact with the substrate s physical or chemical properties, producing a secondary effect that is measured and interpreted. The three most commonly used analytical beams are electron, ion, and photon x-ray beams. Each combination of primary irradiation and secondary effect defines a specific analytical technique. The IC substrate properties that are most frequendy analyzed include size, elemental and compositional identification, topology, morphology, lateral and depth resolution of surface features or implantation profiles, and film thickness and conformance. A summary of commonly used analytical techniques for VLSI technology can be found in Table 3. 

Oils are mixtures of mixed esters with different fatty acids distributed among the ester molecules. Generally, identification of specific esters is not attempted instead the oils are characterized by analysis of the fatty acid composition (8,9). The principal methods have been gas—Hquid and high performance Hquid chromatographic separation of the methyl esters of the fatty acids obtained by transesterification of the oils. Mass spectrometry and nmr are used to identify the individual esters. It has been reported that the free fatty acids obtained by hydrolysis can be separated with equal accuracy by high performance Hquid chromatography (10). A review of the identification and deterrnination of the various mixed triglycerides is available (11). 

The major STEM analysis modes are the imaging, diffraction, and microanalysis modes described above. Indeed, this instrument may be considered a miniature analytical chemistry laboratory inside an electron microscope. Specimens of unknown crystal structure and composition usually require a combination of two or more analysis modes for complete identification. 

This paper describes application of mathematical modeling to three specific problems warpage of layered composite panels, stress relaxation during a post-forming cooling, and buckling of a plastic column. Information provided here is focused on identification of basic physical mechanisms and their incorporation into the models. Mathematical details and systematic analysis of these models can be found in references to the paper. 

Applications With the current use of soft ionisation techniques in LC-MS, i.e. ESI and APCI, the application of MS/MS is almost obligatory for confirmatory purposes. However, an alternative mass-spectrometric strategy may be based on the use of oaToF-MS, which enables accurate mass determination at 5 ppm. This allows calculation of the elemental composition of an unknown analyte. In combination with retention time data, UV spectra and the isotope pattern in the mass spectrum, this should permit straightforward identification of unknown analytes. Hogenboom et al. [132] used such an approach for identification and confirmation of analytes by means of on-line SPE-LC-ESI-oaToFMS. Off-line SPE-LC-APCI-MS has been used to determine fluorescence whitening agents (FWAs) in surface waters of a Catalan industrialised area [138]. Similarly, Alonso et al. [139] used off-line SPE-LC-DAD-ISP-MS for the analysis of industrial textile waters. SPE functions here mainly as a preconcentration device. 

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