Qualitative Analyses Other Applications

NMR spectra can be used to identify unknown compounds through spectral pattern matching. A number of companies, instrument manufacturers, government agencies, and other sources publish collections of reference spectra in electronic format and in hard copy. These spectral databases 

Chemists and materials scientists are working to develop new materials with specific properties such as high strength and high modulus, resistance to temperature extremes, corrosion resistance, 

Solid-state NMR is proving to be a powerful technique for the study of reactions at surfaces. For example, NMR has been nsed in catalysis studies for determining the structure of chanisorbed molecules and for monitoring changes occurring in those structures as a function of tanperature. 

The need to determine the structures of large biological molecules like proteins is driving a new revolution in NMR. Extremely fast multidimensional NMR and new mathanatical approaches, such as G-matrix FT-NMR, are being developed to rapidly collect and process 4D and 5D NMR experiments on biological macromolecules. Articles on these developments can be found in Chemical and Engineering News, December 23,2002, p. 7 and January 27,2003, p. 15. 

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Because most research effort in the human reliability domain has focused on the quantification of error probabilities, a large number of techniques exist. However, a relatively small number of these techniques have actually been applied in practical risk assessments, and even fewer have been used in the CPI. For this reason, in this section only three techniques will be described in detail. More extensive reviews are available from other sources (e.g., Kirwan et al., 1988 Kirwan, 1990 Meister, 1984). Following a brief description of each technique, a case study will be provided to illustrate the application of the technique in practice. As emphasized in the early part of this chapter, quantification has to be preceded by a rigorous qualitative analysis in order to ensure that all errors with significant consequences are identified. If the qualitative analysis is incomplete, then quanhfication will be inaccurate. It is also important to be aware of the limitations of the accuracy of the data generally available... 

The latest innovation is the introduction of ultra-thin silica layers. These layers are only 10 xm thick (compared to 200-250 pm in conventional plates) and are not based on granular adsorbents but consist of monolithic silica. Ultra-thin layer chromatography (UTLC) plates offer a unique combination of short migration distances, fast development times and extremely low solvent consumption. The absence of silica particles allows UTLC silica gel layers to be manufactured without any sort of binders, that are normally needed to stabilise silica particles at the glass support surface. UTLC plates will significantly reduce analysis time, solvent consumption and increase sensitivity in both qualitative and quantitative applications (Table 4.35). Miniaturised planar chromatography will rival other microanalytical techniques. 

Krzek et al. [35] reported the qualitative identification and quantitative analysis of the mixtures of OTC, tiamulin, lincomycin, and spectinomycin in the veterinary preparations by using TLC/densitometry. As stationary phase, they used precoated TLC aluminum sheets, and the mobile phases were mixtures of 10% citric acid solution, hexane, ethanol (80 1 1, v/v), and n-butanol, ethanol, chloroform, 25% ammonia (4 5 2 5, v/v). The other application of TLC or HPTLC for analyzing OTC in the various samples is summarized in Table 2 [36]. 

Even if quantitative results are more often expected for wastewater quality measurement, qualitative information is of great interest, as is the case for other applications of the analytical sciences (in the health sector, the use of test kits and biodiagnostic systems leads to quick and useful information, often far from a classical analytical result). In fact, quantitative analysis gives the concentration not only of one substance, but also of a group of comparable substances (surfactants, PAH,...), and even the value of a specific (TOC, TKN,...) or aggregate (BOD, COD, toxicity,...) parameter. In this context, total indices are often proposed as parameters complementary to classical analytical results [1]. 

Analytical procedures can be classified in two ways first, in terms of the goal of the analysis, and second, in terms of the nature of the method used. In terms of the goal of the analysis, classification can be based on whether the analysis is qualitative or quantitative. Qualitative analysis is identification. In other words, it is an analysis carried out to determine only the identity of a pure analyte, the identity of an analyte in a matrix, or the identity of several or all components of a mixture. Stated another way, it is an analysis to determine what a material is or what the components of a mixture are. Such an analysis does not report the amount of the substance. If a chemical analysis is carried out and it is reported that there is mercury present in the water in a lake and the quantity of the mercury is not reported, then the analysis was a qualitative analysis. Quantitative analysis, on the other hand, is the analysis of a material for how much of one or more components is present. Such an analysis is undertaken when the identity of the components is already known and when it is important to also know the quantities of these components. It is the determination of the quantities of one or more components present per some quantity of the matrix. For example, the analysis of the soil in your garden that reports the potassium level as 342 parts per million (ppm) would be classified as a quantitative analysis. The major emphasis of this text is on quantitative analysis, although some qualitative applications will be discussed for some techniques. See Workplace Scene 1.1. 

Analytical pyrolysis is used frequently in practice for qualitative identification and for obtaining quantitative or semiquantitative information on samples containing polymers, either synthetic or natural. However, most of this work remains unreported in peer reviewed literature but is rather common in industrial laboratories. Since the objects made from plastic or elastomers are typically insoluble or not easily analyzed by other techniques, analytical pyrolysis is very successful in this type of analysis [11]. The very small amount of material necessary for pyrolysis also allows in many cases performance of the analysis without the destruction of the object to be investigated. Qualitative and quantitative work includes applications for the identification of unknown samples and also for quality control purposes, evaluation of starting materials, evaluation of finished products, reverse engineering and competitor s product analysis, etc. [1]. Among other applications, Py-GC/MS can be used to quantitatively differentiate between natural and synthetic organic materials [12]. 

Much effort has been made to detect steroids in biological fluids. Even simple TLC methods have been used for qualitative analysis [38], One method that been used for quantification involves an immunoassay, but several problems exist with that method, most notably cross-reactions and interference with other substances [39], On the other hand, a number of chromatographic methods have been developed to overcome these problems. The majority of analytical methods involved GC, which has good detection limits, but requires previous derivatization [40] of the steroids to accomplish volatilization. Many methods have also been reported using HPLC with UV detection or LC-MS [40, 41], Previously used stationary phases for LC was e.g., Sephadex LH-20, Celite and Lipidex, but they could not be operated with high pressure [42], These columns were therefore slow to run and the separation of steroids was very time-consuming [43], Nowadays applications mainly use HPLC as a separation method with both normal-phase and re-versed-phase chromatography. 

For some applications, the qualitative analysis of metal ions is desired detecting and distinguishing which metal ions might be present in a mixture. For other applications,... 

In theory, GC retention times should be useful for identifying components in mixtures. In fact, however, the applicability of such data is limited by the number of variables that must be controlled to obtain reproducible results. Nevertheless, gas chromatography provides an excellent means of confirming the presence or absence of a suspected compound in a mixture, provided that an authentic sample of the substance is available. No new peaks in the chromatogram of the mixture should appear on addition of the known compound, and enhancement of an exi.st-ing peak should be obseiwed. The evidence is particularly convincing if the effect can be duplicated on different columns and at different temperatures. On the other hand, because a chromatogram provides but a single piece of information about each species in a mixture (the retention time), the application of the technique to the qualitative analysis of complex samples of unknown composition is limited. 

This shows that IRS is a particularly powerful method for damage analysis. With this method fibres, coatings and other deposits, textile auxiliaries and substances causing stains can be identified. Chemical damage to fibres can also be detected by means of specific structural changes. All states of matter can be investigated with IR spectroscopy. Thus in damage analysis the composition of mostly liquid extraction residues is of particular interest. As well as qualitative IRS, quantitative applications are also available, where on the basis of the Lambert-Beer law the determination of the concentration of dissolved substances, the blend ratio in fibre mixtures or estimation of the comonomer content in copolymers is possible. 

Although many people do not know about or. perhaps, understand the details of qualitative analysis, products for home analysis are becoming increasingly available. In some cases, tests for certain chemicals or elements, such as lead, may be performed directly by the consumer in other cases, the consumer may collect samples to be shipped to a laboratory for professional testing. Of course, the quality of such kits varies, but the everyday applications of qualitative analysis are illustrated by the increasing availability of these kits. 

Capillary electrophoresis technology has become an indispensable tool for forensic scientists in the biology field since it is able to provide valuable information to aid in the process of law enforcement. The primary application of the technique is in the qualitative analysis of STRs. Isolation of STR mixtures is also possible using relative peak heights. Other applications of CE include quantitative analysis of PCR products, mtDNA sequencing, and mutation detection for the analysis of plant and bacterial DNA. Based on the performance of the methods illustrated above, it is reasonable to expect future researchers and practitioners to continue working to exploit the capabilities of this robust scientific technique and its application to criminal investigations. 

Since the pioneering work of Thome et al. (1986), many applications of APCI mass spectrometry to the detection and analysis of alkaloids and alkaloid-derived compounds in ETS have been developed. Qualitative analysis of alkaloids in ETS can be performed by APCI-MS/MS however, this technique will not be discussed here. Real-time quantitative analysis is a highly useful technique for determining instantaneous compound concentrations and investigating the reactivity of the title compounds and their relationship and interactions to other compounds found in the indoor environment. Real-time data can be combined with plethysmography to accurately determine inhaled alkaloid dose (deBethizy et al. 1989). Analysis of the decay kinetics of ETS alkaloids can be used to understand relationships between various ETS tracers (Nelson et al. 1990, 1991). Time-weighted... 

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