Media compatibility

Electrophoresis can be carried out using paper or a gel as the supporting medium. Typically, it can only be carried out in media compatible with water because buffers or salt solutions are required to carry the electric current required for separation. CE is carried out in a fused-silica capillary filled with buffer. 

Fig. 5.1.17 Absolute pressure sensor for good media compatibility with pressure inlet port on the bottom of the silicon diaphragm and an on-chip vacuum reference volume, made possible by triplestack anodic bonding...

A polymetric dam material is dispensed into a square shape around the transducer diaphragm and cured. The most critical aspects of this process is the adhesion of the various layers together and the media compatibility of the materials. 

In both commercial and home-built FIA instruments, the injection valve is made of PVC and/or Teflon, the coils and connecting tubes of polyethylene, polypropylene, or Teflon, and the pump tubes of PVC. All these materials are fairly resistant to polar solvents, and as long as aqueous solutions are used throughout, no problems will be encountered. Yet if nonpolar solvents have to be handled, such as in solvent extraction, it is necessary to use pump tubes resistant to these solvents [e.g., Acidflex or Viton tubes made of black flurorplast rubber, or the recently introduced Marprene tubes (see Table 5.1)], Teflon coils, and to construct the system so that the aqueous samples are injected into an aqueous carrier stream (i.e., the Perspex or PV(T made parts of the injection port do not contact the organic solvent). For FIA procedures performed exclusively in non-aqueous media, compatible materials have to be chosen carefully and the injection valve must be made entirely of Teflon or a stainless-steel-Teflon combination, such as that used in chromatographic valves. 

Features Reduces/prevents harmful effect of copper or other metals exc. extraction resist, to oil and aq. media compat. in polyolefins and most org. polymers Regulatory FDA 21 CFR 178.2010... 

Tinter n. Colored pigments ground in media compatible with paint vehicles, added in relatively small proportions to already prepared paints to modify their color. With the introduction of latex paints of many types, tinters have been developed which can be used both with organic solvent-thinned paints and with water-thinned paints. Such dual-purpose tinters are known as universal tinters. 

This new synthesis method provides an improved means of preparing monolithic media compatible with stationary-phase synthesis techniques developed for particulate media. The new technique is compatible with polymeric column hardware and does not require covalent bonding of the monolith to the inner column wall. The use of prepolymerized particles circumvents issues associated with shrinkage problems that are characteristic of conventional monolith syntheses (see Section 3.4.1.6) while providing excellent efficiency for small-molecular weight anions, even under isocratic conditions. 

Features Stable in hard water, si. acidic and alkaline media compat. with other nonionic and anionic detergent bases... 

Features Mild effective in acid and alkaline media compat. in high electrolyte formulations stable over wide pH range... 

Features Mild stable to acid and alkali media compat. with anionic surfactants and most cationic polymers Properties Cl. liq. pH 5.5-6.5 Storage 1 yr. shelf life Mirataine CB [Rhodia Novecare]... 

Features Self-emulsifiying highly stable in acidic and basic media compat. with most pharmaceutical and cosmetic ingredients Properties Wh. wax m.p. 47-55 C acid no. 1 max. sapon. no 2 max. iodine no. 2.0 max. 

Uses Dispersant for polar media particles emulsifier for w/o or o/w emulsions wetting agent for hydrophobic surfs. rust inhibitor for protection of metal surfs. Features Can form extremely stable dispersions in polar media compat. with wide variety of oils and polar soivs. 

In this chapter, we first describe the peculiar electronic structure of 2 and its impact on its chemical reactivity that is opposite from that of ordinary oxygen 02-Then, we compare the respective advantages and limitations of photochemical and chemical methods to generate 2 in a context of industrial development. In particular, we detail the criteria for choosing a reaction medium compatible with both the organic substrate and water-soluble chemical sources of 02- Finally, the main reactions of 2 in organic chemistry are listed and illustrated with two industrially relevant examples recently developed in the fields of perfumery (synthesis of rose oxide) and pharmacy (synthesis of artemisinin). 

Long-chain di-alkyl esters have medium compatibility with most polymers and can act both internally and externally, hence they are often used to obtain a balanced lubrication. 

Internal lubricant with medium compatibility standard for rigid calendering 319 ... 

Features Stable in alkaline medium compat. with many types of surfactants Properties Colorless to yel. liq. readily sol. in water, up to 35% NaOH, acid to pH 3.5 dens. 1.135 g/cm pH 7-8 40% cone. 

The temperature at which filtration will occur can affect the viscosity of the fluid, the corrosion rate of the housing, and the filter medium compatibility. Viscous fluids generally become less viscous as temperature increases. If a fluid is too viscous, it may be advisable to preheat the fluid and to install heater bands in the filter. Thus, it is important to determine the viscosity of a fluid at the temperature at which filtration will occur. 

In a second attempt to extend the scope of Lewis-acid catalysis of Diels-Alder reactions in water, we have used the Mannich reaction to convert a ketone-activated monodentate dienophile into a potentially chelating p-amino ketone. The Mannich reaction seemed ideally suited for the purpose of introducing a second coordination site on a temporary basis. This reaction adds a strongly Lewis-basic amino functionality on a position p to the ketone. Moreover, the Mannich reaction is usually a reversible process, which should allow removal of the auxiliary after the reaction. Furthermore, the reaction is compatible with the use of an aqueous medium. Some Mannich reactions have even been reported to benefit from the use of water ". Finally, Lewis-acid catalysis of Mannich-type reactions in mixtures of organic solvents and water has been reported ". Hence, if both addition of the auxiliary and the subsequent Diels-Alder reaction benefit from Lewis-acid catalysis, the possibility arises of merging these steps into a one-pot procedure. 

There are, however, numerous appHcations forthcoming ia medium- to small-scale processiag. Especially attractive on this scale is the pharmaceutical fine chemical or high value added chemical synthesis (see Fine chemicals). In these processes multistep reactions are common, and an electroorganic reaction step can aid ia process simplification. Off the shelf lab electrochemical cells, which have scaled-up versions, are also available. The materials of constmction for these cells are compatible with most organic chemicals. 

Hydrophilic/hydrophobic properties. In water-based systems, the filler should be compatible with water because filler dispersion occurs in an aqueous medium before a polymer emulsion is added. In general, most fillers are hydropho-... 

Moreover, these experiments reveal some unique properties of the chlorostan-nate ionic liquids. In contrast to other known ionic liquids, the chlorostannate system combine a certain Lewis acidity with high compatibility to functional groups. The first resulted, in the hydroformylation of 1-octene, in the activation of (PPli3)2PtCl2 by a Lewis acid-base reaction with the acidic ionic liquid medium. The high compatibility to functional groups was demonstrated by the catalytic reaction in the presence of CO and hydroformylation products. 

The centrifugal compressor is well established for the compression of gases and vapors. It has proven its economy and uniqueness in many applications, particularly in which large volumes are handled at medium pressures. This compressor is particularly adaptable to steam turbine or other continuous speed change drives, as the two principles of operation and control are quite compatible. It is also adaptable to the electric motor, gas engine, and gas turbine with each installation being specific to a particular problem or process. Installation as well as operating costs can be quite reasonable. 

The most important component in the majority of paints is the binding medium, which determines the physical and chemical properties of the paint. Blends of binding media are often used to impart specific properties to the dry paint film or to suit a particular application method. The compatibility of chemically different types of binders is an important factor to be taken into account by the paint formulator. These properties will be modified, however, to a greater or lesser extent by the nature and quantity of the other components, more especially the pigment. The general characteristics of various binding media are given in Table 14.2. 

Relations (2.46) and (2.47) are equivalent formulations of the fact that, in a dense medium, increase in frequency of collisions retards molecular reorientation. As this fact was established by Hubbard within Langevin phenomenology [30] it is compatible with any sort of molecule-neighbourhood interaction (binary or collective) that results in diffusion of angular momentum. In the gas phase it is related to weak collisions only. On the other hand, the perturbation theory derivation of the Hubbard relation shows that it is valid for dense media but only for collisions of arbitrary strength. Hence the Hubbard relation has a more general and universal character than that originally accredited to it. 

The choice of reaction medium is important and the most important criteria that must be complied with are (i) unreactivity towards reactants and products, (ii) a large range between the melting and boiling points, (iii) good chemical and thermal stability, (iv) compatibility with the analytical methods used to test the reaction, and (v) good solubility of the reactants, and sometimes of products, even if excellent results can be obtained in the heterogeneous phase. 

The condensation of nitro compounds and imines, the so-called aza-Henry or nitro-Mannich reaction, has recently emerged as a powerful tool for the enantioselective synthesis of 1,2-diamines through the intermediate /3-amino nitro compounds. The method is based on the addition of a nitronate ion (a-nitro carbanion), generated from nitroalkanes, to an imine. The addition of a nitronate ion to an imine is thermodynamically disfavored, so that the presence of a protic species or a Lewis acid is required, to activate the imine and/or to quench the adduct. The acidic medium is compatible with the existence of the nitronate anion, as acetic acid and nitromethane have comparable acidities. Moreover, the products are often unstable, either for the reversibility of the addition or for the possible /3-elimination of the nitro group, and the crude products are generally reduced, avoiding purification to give the desired 1,2-diamines. Hence, the nitronate ion is an equivalent of an a-amino carbanion. 

Cultivation of strictly anaerobic organisms requires not only that the medium be oxygen-free, but also that the redox potential of the medium be compatible with that required by the organisms. This may be accomplished by addition of reducing agents such as sulfide, dithionite, titanium(III) citrate, or titanium(IIl) nitrilotriacetate. Any of these may, however, be toxic so that only low concentrations should be employed. Attention has been drawn to the fact that titanium(III) citrate-reduced medium may be inhibitory to bacteria during initial isolation (Wachenheim and Hespell 1984). 

In all cases, alignment media will interact with the solute. The choice of alignment medium therefore is mainly determined by the solute compatibility with respect to charge, specific hydrophobic interactions or even chemical reactions if for example, radicals are stiU present in radically synthesized polymers. 

DG was primarily developed as a mathematical tool for obtaining spahal structures when pairwise distance information is given [118]. The DG method does not use any classical force fields. Thus, the conformational energy of a molecule is neglected and all 3D structures which are compatible with the distance restraints are presented. Nowadays, it is often used in the determination of 3D structures of small and medium-sized organic molecules. Gompared to force field-based methods, DG is a fast computational technique in order to scan the global conformational space. To get optimized structures, DG mostly has to be followed by various molecular dynamic simulation. 

Haberz, P., Farjon, J., Griesinger, G. A DMSO-compatible orienting medium towards the investigation of the stereochemistry of namral products. Angew. Chem. Int. Ed. 2005, 44,... 

Some elastomer sealings that are in contact with the antifreeze mixture may not be stable in such a medium because of consequences such as swelling. The compatibility of ethylene-glycol with certain plastics is shown in Table 14-3. 

---