Qualitative analytical reagents

Dilead hexacyanokisferrate [14402-61-0], Pb2[Fe(CN)6], is a white precipitate that forms when lead acetate is added to Ca2[Fe(CN)6]. It is insoluble in water or dilute acids but is soluble in hot ammonium chloride or ammonium succinate solutions. It has been used as a qualitative analytical reagent in tests for cadmium and chromate. 

Some qualitative analytical reagents for the detection of rare earths elements are given in Tables 1.26 and 1.27. Gravimetric, volumetric, complexometric, precipitation and polarographic methods of analysis of rare earths are summarized in Tables 1.28 to 1.32. 

Finally, it should be mentioned that several analytical methods for chromatographic separation and identification of pyridazines have been developed.Also polarographic determination and other analytical methods were applied. Pyridazines have been proposed as analytical reagents for the spectrophotometric determination of iron or for the qualitative determination of sodium. ... 

Towards the end of the nineteenth century the range of analytical reagents was extended by synthetic organic substances. The most famous of these is dimethyl-glyoxime, introduced in 1905, which forms a beautiful pink precipitate with nickel ions, and is widely used in both the qualitative and quantitative analysis of that metal. 

Spot tests may prove ultimately to be the most, important example of determinations in which traces are major constituents. The technique is well known15 apd has proved very valuable in analytical chemistry. As often carried out, a reagent (specific if possible) is made to react in or on filter paper with the element sought, usually present as a trace. The results are normally qualitative or semiquantitative, it often being difficult to make them quantitative by methods other than x-ray emission spectrography.16 With this technique, however, not only is it possible... 

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 ... 

The factors chosen for study were the concentration of the ion-pairing reagent, the solution pH ( quantitative factors) and the acid chosen for pH adjustment (formic, acetic, propionic and trifluoroacetic acids) ( qualitative factor). The effect of these factors was assessed by using responses that evaluated both the HPLC (the number of theoretical plates and the retention time) and MS performance (the total peak area and peak height) for each of the four analytes studied, i.e. 1-naphthyl phosphate (1), 1-naphthalenesulfonic acid (2), 2-naphthalenesulfonic acid (3) and (l-naphthoxy)acetic acid (4). 

Difficulties are encountered in the qualitative and quantitative analysis of carbohydrate mixtures because of the structural and chemical similarity of many of these compounds, particularly with respect to the stereoisomers of a particular carbohydrate. As a consequence, many chemical methods of analysis are unable to differentiate between different carbohydrates. Analytical specificity may be improved by the preliminary separation of the components of the mixture using a chromatographic technique prior to quantitation and techniques such as gas-liquid and liquid chromatography are particularly useful. However, the availability of purified preparations of many enzymes primarily involved in carbohydrate metabolism has resulted in the development of many relatively simple methods of analysis which have the required specificity and high sensitivity and use less toxic reagents. 

Despite some refinements in the methods, the basic principles and protocols of gel electrophoresis have not changed appreciably since their introduction. Proteins are introduced into a gel matrix and separated by the combined effects of an electrical field, buffer ions, and the gel itself, which acts as a protein sieve. At the completion of the electrophoresis run, separated proteins in the gel are stained to make them visible, then analyzed qualitatively or quantitatively. The topic has been covered in numerous texts, methods articles, and reviews.1-11 In addition, apparatus and reagents for analytical and preparative gel electrophoresis are available from several suppliers. 

Tetrazolium salts are used in analytical chemistry as reagents for qualitative and quantitative determination of various compounds. These salts are also used in chemical kits for diagnostics of various diseases. The number of publications on analytical uses of tetrazolium salts is too large to be discussed in this chapter. Therefore, we direct the reader to surveys on preparative methods and properties of tetrazolium salts, where the use of these compounds in chemical analysis is also discussed C1990KGS1587, 1998RCR671, 2002RCR721>. 

Standardization Classically, to standardize means to compare with or conform an assay of unknowns to established standards. In quantitative analytical work numbers readily allow for conforming to such standards. In semi-quantitative or qualitative assays such as immunocyto- or immunohistochemistry, which frequently conclude with an opinion, only subjective comparisons to carefully selected tissue and reagent controls can be used to monitor and maintain excellence. 

Structural factors that influence coordination A brief outline of the more important structural factors, with respect to the metal ion as well as the ligand, that determine the stabihty of coordination compounds should be helpful as a guide to qualitative predictions about the apphcabihty of organic reagents for analytical purposes. At the outset it should be recognized that the stability of a coordination compound, expressed by its formation constant, is only one of several factors that determine the completeness of precipitation or extraction of a metal ion. 

In conclusion, it can be stated that spectroscopic techniques will further dominate the analytical tools of the future with respect to qualitative and quantitative assays. This is because of their speed and the enormous information content of the spectra, especially in the infrared, and the fact that reagent-free multicomponent methodologies are available. The widespread diffuse reflection technique certainly has to compete with others in the laboratory and at the production site. However, for the study of bulk and dispersed systems, it will often be the method of choice. There are additional developments concerned with dedicated instruments and user-friendly interfaces, in which che-mometrics play an important role. It is hoped that the sophisticated algorithms presented in the literature will... 

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