Analytical methods classification according

Table 26.1 Classification of Analytical Methods in the European Union According to their Validation Status...

In summary, this set of 264 nonfractionated whole soil samples, which could be grouped according to major soil units of the World Reference Base soil classification, is possibly the largest sample set that has been characterized by an extremely sensitive, versatile analytical method under identical experimental conditions. 

Use of the term gel as a classification originated during the late 1800s as chemists attempted to classify semisolid substances according to their phenomenological characteristics rather than their molecular compositions. At that time, analytical methods needed to determine chemical structures were lacking. The defines gels (sometimes called jellies) as... 

Analytical methods are often classed according to size of sample. Such classification is arbitrary and there is no sharp dividing line. The analysis may be classed... 

Classification of Analytical Methods According to Size of Sample... 

For all those separation cases, however, which attempt to separate a particle collective according to certain properties of the particulate solids, agglomeration is most often undesired. Techniques for which this statement is true include screening, sifting, classification, sorting, flotation, and, as a general analytical method, particle size characterization. It should also be realized that the respective separation property is not only size it could be density, shape, color, chemical composition, and others. 

A second classification is according to the plant material that has to undergo analysis. The specific application of the analytical method is determined by the special anatomical, physiological, and biochemical properties of the raw material and the technology used in processing. This classification was used in Volumes 6 to 8, and for some later volumes in the series. 

Chapters 6 and 7 are dedicated to the table s chemical content, especially the conceptual framework employed in its construction. Chapter 6 will deal with the classification s most general principle, the principle of classification according to composition. Classification according to composition is not a universal mode of chemical classification, but a historical one. Based on our principal discussion of the modem concept of chemical composition in part I, three of the historical preconditions of this classification will be studied in this chapter 1) the kind of chemical substances presupposed by this classificatory principle that is, pure chemical substances which became the subject of chemical practice in the early modem period 2) the demarcation of the modem notion of composition from earlier concepts of the constitution of substances and 3) the development of the analytical method of procuring certain knowledge of chemical composition. 

The example shows that Stahl s analytical method differed greatly from the analytical ideal of analysis followed by resynthesis. He deduced the presence of ultimate principles from his observations of changes of properties of compound substances in chemical reactions. Like Homberg s classification, his classification according to component parts rested not on actual investigations of isolated principles, but on interpretations of experiments with ordinary substances in light of the philosophy of principles. 

The analysis of the classification of plant materials in the Methode de nomenclature chimique, presented at the beginning of chapter 14, creates an important link between parts II and III of this book. This analysis first shows the ambition of Lavoisier and his collaborators to extend classification according to composition to plant substances, and, second, their failure in terms of collective acceptance. The next section of the chapter continues this analysis of their failure inasmuch as it points out the theoretical limits of the Lavoisierian analytical program. As Lavoisier s theory of the elemental composition of organic substances did not include the assumption of stoichiometric organic compounds, it was unsuitable as a working tool for the envisioned analytical mode of identification and classification of organic compounds. 

The various contributions can also be classified in accordance with the optimization techniques used. However, this method of organization gives rise to an even more diverse classification, since the techniques used range all the way from rules of thumb (A3-A5, M6-M8, Ol, T2) and analytical solution (S8) to the more recent developments in mathematical programming. Most of the techniques reported are continuous, but some are discrete (C8, R5) and still others are of mixed integer types (G3). Table VI shows such a classification for the papers reviewed. It is clearly beyond the scope of this review to delve into the mathematical bases of these methods. We shall... 

In this section a variety of analytical separations reported in the literature are reviewed to show the wide structural diversity of eluite which can be separated by RPC and to assist the reader in becoming similar with the use of this fluid chromatographic technique. The descriptions are ar-ranged according to the matrix in which an analyte is found or the area of - h istry in which the samples are generally encountered. Thus theophylline, for example, is regarded as a nucleotide and, for the most part, its analysis in food samples is found with appropriate cross references. On the other hand, the separations of pharmaceuticals found in serum, urine, and pharmaceutical samples are cited separately. It is hoped that this method of classification may serve the purposes of those wh e analytical interests are incidental to their primary research pursuits. 

Various criteria can be considered in the classification of the SEC applications. The most important are the analytical SEC procednres. The preparative applications, which encompass the purification of complex samples before their further treatment, draw rather wide attention. In this latter case, analytes are preseparated by SEC according to the size of their components and either macromolecular or low molecular fractions are subject to further analyses by other methods. The production oriented SEC did not find wide application in the area of synthetic polymers due to both the high price of organic solvents and the ecological considerations. 

Table 1.1 Classification of analysis surface techniques used in the study of cultural heritage according to the method of excitation and the resulting emitted corpuscles carrying analytical information...

An alternative interesting classification approach has been proposed within the Codex Committee for Residues of Veterinary Drugs in Foods (20). In this approach, methods are classified according to their performance attributes. This alternative approach defines methods by the level of analytical detail or information provided concerning the amount and nature of the analyte of interest, and identifies three levels. 

The surface extended X-ray absorption fine structure (SEXAFS) method can use either an electron or an ion detection signal (Koningsberger and Prins, 1988). The classification of analytical techniques may be considered in terms of incident and emitted radiation, resolution, and sensitivity, according to Table 4.7, which lists eight of the many possible techniques (Briggs and Seah, 1990 Buckley, 1981 Watts, 1990). Many of the surface analysis techniques were introduced into many laboratories over the years of 1968 to 1970. This resulted from the maturing of clean vacuum systems which could achieve pressures, down to 10"8 Pa. At these low pressures, it is possible to obtain and maintain atomically clean surfaces. 

Liquid chromatographic methods may be classified according to either the mechanism by which analytes are retained on the column or the mechanism by which they are removed from it. The mechanism of retention classification is the most popular scheme, and five major retention mechanisms have been identified ... 

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