Quantitative and Qualitative Analysis

For qualitative analysis, one has to look at the energy of the X-ray peaks and identify the elements from which these characteristic lines have originated. The X-ray energies of interest lie below 20keV, where the X-rays of element with Z Ab and L X-raj of the heavy elements are observed. Table 1.9 indicates the energies of K and L X-rays of a few elements  

For a sample having many elements, the L X-ray peak of a heavy element may coincide with the K X-ray peak of a light element causing confusion in analysis. Many elements, present in relatively very small quantity cause difEculty in their detection. The presence of two strong L-lines can be used to remove interference, for instance the determination of s2Pb can be made in the presence of 33AS by using the L(3 component. 

When a given sample contains many elements, the X-ray lines for different elements are depicted from the energies of various X-ray lines. The energy resolution i.e., full-width at half-maximum (FWHM) is the limiting parameter for many X-ray measurements. This is so because if the energy resolution is poor, there will be overlap of component X-ray lines of one element with that of the other due to the small energy difference between the X-ray lines of 

The Sum peaks in the spectrum occur when the count rates are so high that when the two X-rays impinge on the detector virtually instantaneously, the pulse created and measured is the sum of the two X-ray energies. For 

There is seldom a unique way to design a measurement process. Even an explicitly defined analysis can be approached in more than one ways. Different studies have different purposes, different financial constraints, and are carried out by staff with different expertise and personal preferences. The most important step in a study design is the determination of the purpose, and at least a notion of the final results. It should yield data that provide useful information to solve the problem at hand. 

The objective of an analytical measurement can be qualitative or quantitative. For example, the presence of pesticide in fish is a topic of concern. The questions may be Are there pesticides in fish If so, which ones An analysis designed to address these questions is a qualitative analysis, where the analyst screens for the presence of certain pesticides. The next obvious question is How much pesticide is there This type of analysis, quantitative analysis, not only addresses the presence of the pesticide, but also its concentration. The other important category is semiqualitative analysis. Here 

Organics Extraction, concentration, cleanup, derivatization GC, HPLC, GC/MS, LC/MS 

Volatile organics Transfer to vapor phase, concentration GC, GC-MS 

Metals Extraction, derivatization, concentration, speciation UV-VIS molecular absorption spectrophotometry, ion chromatography 

Gas chromatography by itself does not provide unambiguous component identification. However, if a component does not elute from a column at the point expected from prior experience, it is almost certain that the component is not present in the mixture. If a peak is obtained at the correct time, it does not confirm identity, only makes it possible. If the sample is then analysed on a second stationary phase and it is found that the component of interest also has the correct elution time for the second phase, then confidence in the identification increases. Coupling the gas chromatograph to a mass spectrometer and/or a Fourier transform infrared spectrometer is the optimum means for unambiguous component identification. 

Gas chromatography is an excellent quantitative technique as the peak areas (or heights for uniform-shaped peaks) are a measure of the amount of material present. There are numerous ways of carrying out quantitative 

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Silver nitrate is used extensively in qualitative and quantitative analysis. 

Nondestructive qualitative and quantitative analysis of impurities and defects, and their distributions in luminescent materials... 

The characterisation of materials is a central necessity of modern materials science. Effectively, it signifies making precise distinctions between different specimens of what is nominally the same material. The concept covers qualitative and quantitative analysis of chemical composition and its variation between phases the examination of the spatial distribution of grains, phases and of minor constituents the crystal structures present and the extent, nature and distribution of structural imperfections (including the stereological analysis outlined in Chapter 5). 

Note The reagent can be employed for qualitative and quantitative analysis on silica gel and RP layers. Ammonia, amine and acid-containing mobile phases should be completely removed beforehand. Amino phases cannot be employed. The NBD-chloride reagent is not as sensitive as the DOOB reagent (qv.) on RP phases. 

The retention gap method (1, 2) represents the best approach in the case of qualitative and quantitative analysis of samples containing highly volatile compounds. The key feature of this technique is the introduction of the sample into the GC unit at a temperature below the boiling point of the LC eluent (corrected for the current inlet pressure), (see Eigure 2.2). This causes the sample vapour pressure to be below the carrier gas inlet pressure, and has two consequences, as follows ... 

X-ray photoelectron spectroscopy (XPS), which is synonymous with ESCA (Electron Spectroscopy for Chemical Analysis), is one of the most powerful surface science techniques as it allows not only for qualitative and quantitative analysis of surfaces (more precisely of the top 3-5 monolayers at a surface) but also provides additional information on the chemical environment of species via the observed core level electron shifts. The basic principle is shown schematically in Fig. 5.34. 

In practice, it is probable that both of the effects discussed contribute to the overall peak asymmetry. Unfortunately, peak asymmetry varies in extent from the very obvious to the barely noticeable and because of this, peak asymmetry is often dismissed as the normal shape of a single solute peak. Such an assumption can cause serious errors in both qualitative and quantitative analysis. 

Waters MD, Stack HF, Jackson MA, et al. 1994. The performance of short-term tests in identifying potential germ cell mutagens A qualitative and quantitative analysis. Mutat Res 341 109-131. 

Manning JM et aJ Normal and abnormal protein subunit interactions in hemoglobins.] Biol Chem 1998 273 19359-Mario N, Baudin B, Giboudeau J Qualitative and quantitative analysis of hemoglobin variants by capillary isoelectric focusing. J Chromatogr B Biomed Sci Appl 1998 706 123-Reed W, Vichinsky EP New considerations in the treatment of sickle cell disease. Annu Rev Med 1998 49 46l. 

Jackman, R.L., Yada, R.Y., and Tung, M.A., Review separation and chemical properties of anthocyanins used for their qualitative and quantitative analysis, J. Food Biochem., 11, 279, 1987. 

An important technique for the qualitative and quantitative analysis of different macromolecular materiafs is based on the efectrophoretic separation of particfes having different transport vefocities (e.g., because they have different zeta potentiafs). This technique is used for the anafysis of proteins, pofysaccharides, and other naturally occurring substances whose molecular size approaches that of colloidal particles (for more details, see Section 30.3.4). It is an advantage of the electrophoretic method that mild experimental conditions can be used—dilute solutions with pH values around 7, room temperature, and so on—which are not destructive to the biological macromolecules. 

Modem planar chromatography is suitable not only for qualitative and quantitative analysis but also for preparative purposes. The separation efficiency of a thin-layer chromatographic system is independent of this intended purpose and is mainly determined by the quahty of the stationary phase, that is to say, by the applied coated layer. Therefore, progress in modem planar chromatography can be attributed not only to the development of the efficiency of the instmments but also to a large extent to the availability of high-quahty precoated layers. And today, as in the past, bulk sorbents for self production, especially of preparative layer chromatography (PLC) layers, are widely used. 

HPLC is a very powerful technique for qualitative and quantitative analysis. In the support of process development, HPLC plays an important role in monitoring a reaction, since each reaction component can be quantitated. In this role, the HPLC method must be fast, rugged, and specific, capable of separating all reactants, products, and byproducts. Development of appropriate analytical methods is often a rate-limiting step in process development. 

For the development of the LANA route, analytical techniques such as GC, TLC, FIPLC, NMR, and GC/MS were used. GC methods were developed to monitor formation of the Grignard reagent. Since all of the components of the LANA route are unstable to the elevated temperatures of GC, FIPLC and TLC techniques were chosen for qualitative and quantitative analysis of reaction samples, to monitor reaction progress, and to determine the purity of intermediates and final product. Because the process development time was limited and the LANA process was entirely dependent on HPLC analysis, we set criteria for the development of HPLC methods ... 

It is of interest to examine the development of the analytical toolbox for rubber deformulation over the last two decades and the role of emerging technologies (Table 2.9). Bayer technology (1981) for the qualitative and quantitative analysis of rubbers and elastomers consisted of a multitechnique approach comprising extraction (Soxhlet, DIN 53 553), wet chemistry (colour reactions, photometry), electrochemistry (polarography, conductometry), various forms of chromatography (PC, GC, off-line PyGC, TLC), spectroscopy (UV, IR, off-line PylR), and microscopy (OM, SEM, TEM, fluorescence) [10]. Reported applications concerned the identification of plasticisers, fatty acids, stabilisers, antioxidants, vulcanisation accelerators, free/total/bound sulfur, minerals and CB. Monsanto (1983) used direct-probe MS for in situ quantitative analysis of additives and rubber and made use of 31P NMR [69]. 

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 Conventional GC is a workhorse in the qualitative and quantitative analysis of polymer additives in complex mixtures and has found numerous applications. Both GC and auxiliary techniques are particularly useful for characterisation of (semi)volatile constituents and additives ranging from gases to hydrocarbon waxes (fatty acids and their... 

Applications Van der Maeden et al. [646] first used GE-HPLC for the qualitative and quantitative analysis of oligomeric mixtures, such as low-MW resins (epoxy up to 16-mer, o-cresol novolak up to 16-mer, p-cresol novolak up to 13-mer), prepolymers (poly-(2,6-diphenyl-p-phenylene oxide) up to 20-mer), PET (up to 14-mer) and ethoxylated octaphenol surfactants (up to 19-mer). In many GE-HPLC separations of oligomeric mixtures, a compromise has to be found between sample loading, injection volume and compatibility of the sample solvent and the initial phase system. Therefore,... 

CE can be used for both qualitative and quantitative analysis. Good reproducibility in migration times... 

As the majority of stabilisers has the structure of aromatics, which are UV-active and show a distinct UV spectrum, UV spectrophotometry is a very efficient analytical method for qualitative and quantitative analysis of stabilisers and similar substances in polymers. For UV absorbers, UV detection (before and after chromatographic separation) is an appropriate analytical tool. Haslam et al. [30] have used UV spectroscopy for the quantitative determination of UVAs (methyl salicylate, phenyl salicylate, DHB, stilbene and resorcinol monobenzoate) and plasticisers (DBP) in PMMA and methyl methacrylate-ethyl acrylate copolymers. From the intensity ratio... 

Principles and Characteristics As mentioned already (Section 3.5.2) solid-phase microextraction involves the use of a micro-fibre which is exposed to the analyte(s) for a prespecified time. GC-MS is an ideal detector after SPME extraction/injection for both qualitative and quantitative analysis. For SPME-GC analysis, the fibre is forced into the chromatography capillary injector, where the entire extraction is desorbed. A high linear flow-rate of the carrier gas along the fibre is essential to ensure complete desorption of the analytes. Because no solvent is injected, and the analytes are rapidly desorbed on to the column, minimum detection limits are improved and resolution is maintained. Online coupling of conventional fibre-based SPME coupled with GC is now becoming routine. Automated SPME takes the sample directly from bottle to gas chromatograph. Split/splitless, on-column and PTV injection are compatible with SPME. SPME can also be used very effectively for sample introduction to fast GC systems, provided that a dedicated injector is used for this purpose [69,70],... 

Applications TLC-MS can be applied to qualitative and quantitative analysis of a very wide range of... 

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