The Stabilities of Organic Substances

The first question to be answered is whether or not the sample is volatile enough to be analyzed by GC. GC columns are currently available with upper temperature limits of around 350 °C. Hence, compounds should be sufficiently volatile at this temperature to be analyzed by GC. A second requirement for the sample, which becomes the more relevant the higher the temperatures used, is the thermal stability of the sample, both in the column, as well as in the injector, which in conventional GC is operated at a temperature slightly above that of the column. Because of the limited stability of organic substances at higher temperatures, extremely high temperatures do not seem to be very... 

The RMs for inorganic analytes were prepared following well established procedures, already in use since several years. On the contrary, novel approaches for the preparation of RMs for analysis of organic compounds in water (PAHs and pesticides) were explored and tested through the SWIFT-WFD PT campaigns, with a positive outcome of the results obtained. These data could serve for future developments in the field of RMs for organic compounds in water. Such quality control tools are, at present, missing because of still unsolved technical difficulties related to the stability of these substances in the water matrix. 

It is obvious that two main factors control the stability of organic molecules. First, the intrinsic stability of organic molecules stabilizes aromatic substances and lipids. Second, the cross linkage between biomolecules inhibits the interaction of enzymes. Only reactions forming small radicals are able to break bonds of cross linked structures and release breakdown products. 

This chapter reviews the abiotic processes that can lead to the stabilization of organic phosphorus in soils and the aquatic environment. In particular, we examine the role of adsorption to soil minerals, complex-ation reactions, precipitation with polyvalent cations and the incorporation of organic phosphorus into humic substances in stabilizing organic phosphorus. We then discuss the effects of soil solution chemistry on these reactions, as well as the effects of these reactions on the environment. 

Foods naturally provide a series of substances that maintain the vital processes and normal development of the body, but sometimes it is desirable to add foreign substances to foods in order to modify some aspect of its properties these substances are called food additives. The advantages of food additives are undeniable and so no country prohibits them entirely. Currently, the establishment of international positive lists and the acceptable daily intake (ADI) instituted by international organizations ensure that these additives, used at a normal dosage, will not have toxic effects on the human body. Analytical methods for the determination of additives have been developed so that the stability of these substances until the food s consumption can be monitored and also to ensure that the additives are within the Umits established by legislation. The sample treatment... 

Effect of Internal Phase Composition. In addition to the factors mentioned above, the stability of the extracting emulsion is influenced significantly by the composition of the internal phase. Among the factors which play the greatest role in determining the stability are the pH and ionic strength of the internal phase and the presence of organic substances (7). 

This is an essential topic for biochemists and biochemical engineers. Biochemical reactions involve both cellular and enzymatic processes, and the principal differences between biochemical and chemical reactions lie in the nature of the living systems. Biochemists and biochemical engineers can stabilize most organic substances in processes involving microorganisms. 

Among aminoacetylenes with different numbers of morpholinopropynyl groups, a substance has been found that displays antihypotoxic, thermoprotecting properties, increasing the stability of animals to intoxication by phosphor organic compounds and the salts of toxic metals. Because the efficiency of this substance exceeds that of azomopine 103 and it is nontoxic, it could be of interest to clinical medicine after additional studies. 

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