Qualitative organic analysis of mixtures

In general, the reactions of organic compounds at a voltammetric electrode are slower and more complex than those for inorganic species. Consequently, theoretical intei-pretation of the data is often more difficult or impossible. Generally, a much stricter adherence to detail is required for quantitative work. Despite these handicaps, organic polarography has proved fruitful for the determination of structure, the quantitative analysis of mixtures, and occasionally the qualitative identification of compounds. 

The rapid evolution of microcomputers has led to the derivative transformation of spectral data, which offer a powerful tool for both qualitative and quantitative analysis of mixtures of organic compounds. The method has found increasing application in UV-visible spectrophotometric analysis of organics for background correction and for resolution enhancement. The ability to eliminate matrix interferences such as irrelevant absorption and light scattering has been of particular value. 

A number of approaches have been developed, mainly based upon two-dimensional TLC, for qualitative analysis of mixtures of surfactants. These are briefly covered in Chapter 5. TLC spots are commonly identified by removing the silica gel from the plate and extracting the organic material with a polar solvent. With careful technique, subsequent... 

Metal salicylates are occasionally incorporated into mixtures of unknowns for qualitative inorganic analysis. During the conventional group separation, organic radicals are removed by evaporation with nitric acid. When salicylates are present, this can lead to formation of trinitrophenol through nitration and decarboxylation. This may react with any heavy metal ions present to form unstable or explosive picrates, if the evaporation is taken to dryness. The MAQA alternative scheme of analysis obviates this danger. 

Methylene iodide, 300 Michael reaction, 912, 913, 914 Michler s ketone, 982 Mixed melting point, 34, 229, 1028 Mixtures of organic compounds, qualitative analysis of, 1090 -1100 preliminary examination, 1093, 1094 ... 

High performance liquid chromatography (HPLC) has become one of the most powerful tools in contemporary organic analysis as the separation technique which can separate very complex mixtures of compounds and provide qualitative and quantitative information on the sample useful for the identification and determination of sample components. 

Polyphosphonic acids can be separated on a special latex-based anion exchanger. They are photometrically determined after complexation with ferric nitrate [27] (see Section 3.3.5.2). This method enables a qualitative analysis of inorganic and organic phosphates that are contained in conditioners. Fig. 8-27 illustrates this with the chromatogram of a commercial product. Clearly, it is a multicomponent mixture with two main components and several minor components. 

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