Separatory Methods

2 Physical Measurements. - The use of aryl boronic acid derivatives as sugar sensors is referred to in Part 2.4 above. 

A review article on dehydroascorbic acid (72 refs.) covered, in addition to its chemistry, many methods for its separation and analysis.  

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Because they are important, the phenolics and their roles in wine have been studied considerably (I), but more needs to be known. Since different classes of phenols behave quite differently in the various roles as pigments, oxidation substrates, flavors, etc., separate consideration and analysis is essential to completely understand them. Every individual phenol should be separately determined precisely and quantitatively. Chromatography may solve these problems, but for now, chromatography and other detailed separatory methods have drawbacks, particularly for economical application to many individual wine or grape samples. 

In some separatory methods chemical reactions are required to convert or modify a component of the mixture to a form which either constitutes a new phase or enables the substance to be distributed to a second phase. 

Crystallisation, precipitation, chromatography, and electrophoresis belong to this category of separatory methods. 

ABSTRACT This review is concerned with non-isoprenoid phenolic lipids typified by compounds biosynthesised by the polyketide pathway. Botanical, biological and entomological sources of such phenolic lipids are described which contain monohydric phenols, notably cardanol and relatives, dihydric phenols such as cardols, alk(en)ylresorcinols,urushiols and phenolic acids, particularly anacardic acids. Some recently investigated mixed types of dihydric phenolic lipids are included. Separatory methods are briefly reviewed. Synthetic methods for the saturated and unsaturated members of the three main classes of interest in structure/activity studies are summarised. Biological properties of members of the three main classes are given and discussed. 

Prior to structural elucidation and possible eventual synthesis, the isolation of component phenolic lipids in a pure state is essential. The cold methods of thin layer chromatography (TLC), column chromatography (CC), flash chromatography, high performance liquid chromatography (HPLC) and hot methods (GC), often after derivatisation, are well established. Argentation versions of these separatory methods are less common but are desirable for the rapid separation of unsaturated constituents. 

Accordingly many procedures have been proposed for speciation. Amongst the most popular are the so-called hybrid techniques which couple separatory methods such as chromatography with detection methods such as optical or mass spectrometry. This has led to a proliferation of abbreviations, such as GC-MS, GC-AAS, GC-ICP-AES, GC-ICP-MS, HPLC-AAS, HPLC-ICP-MS, HPLC-ICP-AES, SFC-ICP-MS and CZE-ICP-MS, which read more like alphabet soup than science. 

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