Stability 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... 

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. 

The term biochemical stabilization refers to the biotic or abiotic production of organic substances that are refractory to decomposition by microorganisms and contribute, through condensation and complex formation, to the stabilization of otherwise easily decomposable substrates such as enzymes. This stabilization process coincides with the process of humification. 

Crystalline hydrates of metal ions and of organic substances, especially those with N—H and O—H bonds, are numerous. For metal ions, the oxygen is always bound to the metal and the lone pairs on it can be directed toward the metal and involved in bonding but can, however, also form H bonds. There is hence flexibility, allowing stabilization in lattices of many different types of hydrated structure. 

The pre-reacted substance is ground and formed after adding an organic binder. The firing temperatures lie in the range 1000-1400 X both temperature and atmosphere have to be chosen with respect to the stability of the substances. With the exception of hard ferrites the firing is taken to complete sintering. The properties of the product depend on the character of the polyciystalline structure. A coarser... 

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. 

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