Extractable species, classes

This large and important class of extractants includes the neutral and acidic esters of ortho phosphoric acid and related compounds, the phosphonates, phosphinates and phosphine oxides. The class divides naturally into neutral and acidic compounds by the differences in extraction mechanism. The neutral compounds extract by solvation of a neutral complex in the organic phase by the phosphoryl oxygen, while the acidic compounds, in general, operate by an ion-exchange reaction to form an extractable species. Further solvation may occur in the organic phase in some extraction systems of this type. 

Coral Species Class of Substances Extraction Media and Extracted Substances Biological and Ecological Activity References... 

Animals that do not readily accept pelleted feeds may be enticed to do so if the feed carries an odor that induces ingestion. Color development is an important consideration in aquarium species and some animals produced for human food. External coloration is desired in aquarium species. Pink flesh in cultured salmon is desired by much of the consuming pubHc. Coloration, whether external or of the flesh, can be achieved by incorporating ingredients that contain pigments or by adding extracts or synthetic compounds. One class of additives that imparts color is the carotenoids. 

Carrageenan. The term carrageenan [19000-07-1] is the generic description for a complex mixture of sulfated polysaccharides that are extracted from certain genera and species of the class Fhodophjceae red seaweed. 

Before leaving consideration of this group of compounds, mention should be made of one unusual species of this general class. Tabushi, Kobuke and Nishiya have reported a polymer-bound hexaketone, illustrated below as compound 29, which is apparently of use in binding uranyl (UO2++) ions. The polymer has, in fact, been utilized in extraction of the uranyl ion directly from seawater . 

Flubendiamide is an example of a new chemical class of insecticides that have been termed phthalic acid diamides (Nauen 2006, Copping and Duke 2007). They are related to the alkaloid ryanodine, which is extracted from Ryania species. Ryanodine affects muscles by binding to calcium channels of the sarcoplasmic reticulum. Ca + ions act as intracellular messengers, and their flux is modulated by calcium channels of this type. The toxic action of ryanodine and synthetic insecticides related to it is due to the disturbance of calcium flux. 

As described in Section 4-1. one important class of chemical reactions involves transfers of protons between chemical species. An equally important class of chemical reactions involves transfers of electrons between chemical species. These are oxidation-reduction reactions. Commonplace examples of oxidation-reduction reactions include the msting of iron, the digestion of food, and the burning of gasoline. Paper manufacture, the subject of our Box, employs oxidation-reduction chemishy to bleach wood pulp. All metals used in the chemical industry and manufacturing are extracted and purified through oxidation-reduction chemistry, and many biochemical pathways involve the transfer of electrons from one substance to another. 

In this chapter, the main analytical techniques and the methods currently employed in industrial and research laboratories for the analysis of important classes of additives are reviewed. The use of both gas chromatographic and liquid chromatographic methods coupled with mass spectrometry features prominently. Such methodology enables the sensitive and specific detection of many types of organic additives in polymeric materials to parts per billion (jig/kg) levels. Much of the development of these methods has been undertaken as part of research into the migration or extraction of species from food-contact and medical materials [5-7], This chapter also includes some discussion on the analysis of residual monomers and solvents. 

As in the other -omics, analyses may be directed at a specific metabolite, at all metabolites in a given system in a shot-gun approach, or at accessible groups of molecules in profiling experiments. In that also the technology varies. In addition, the chemistry of different metabolites is very heterogeneous since it involves hydrophobic lipids, hydrophilic carbohydrates, ionic inorganic species, and other secondary natural products and already the choice of solvent in metabolite extraction dictates which types of molecules will be present (Fig. 10.8). Therefore, total metabolome profiling is not possible, because no analytical method will be able to accommodate all the different molecule classes at once. 

The batrachotoxins were the first class of unique alkaloids to be characterized from skin extracts of frogs of the family Dendrobatidae (see ref. 23 for a review of amphibian alkaloids). Batrachotoxin was detected in only five species of dendrobatid frogs and these frogs were then classified as the monophyletic genus Phyllobates, based in part on the presence of batrachotoxins (24). However, levels of batrachotoxins differ considerably, with the Colombian Phyllobates terribilis containing nearly 1 mg of batrachotoxins per frog, while the somewhat smaller Phyllobates bicolor and Phyllobates aurotaenia, also from the rain forests of the Pacific versant in Colombia, contain 10-fold lower skin levels (8). The two... 

This diversity in solvent properties results in large differences in the distribution ratios of extracted solutes. Some solvents, particularly those of class 3, readily react directly (due to their strong donor properties) with inorganic compounds and extract them without need for any additional extractant, while others (classes 4 and 5) do not dissolve salts without the aid of other extractants. These last are generally used as diluents for extractants, required for improving then-physical properties, such as density, viscosity, etc., or to bring solid extractants into solution in a liquid phase. The class 1 type of solvents are very soluble in water and are useless for extraction of metal species, although they may find use in separations in biochemical systems (see Chapter 9). 

The ionic extractants are those chemicals that carry within an ion pair a labile cation or anion, which will exchange with the appropriate metal species in the aqueous phase. Their role may be regarded as a form of liquid ion exchange. Several commercially available amines belong to this class, are shown in Figure 17. 

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