Cetyltrimethylammonium ion

It follows from the above that the mechanism for electrical potential oscillation across the octanol membrane in the presence of SDS would most likely be as follows dodecyl sulfate ions diffuse into the octanol phase (State I). Ethanol in phase w2 must be available for the transfer energy of DS ions from phase w2 to phase o to decrease and thus, facilitates the transfer of DS ions across this interface. DS ions reach interface o/wl (State II) and are adsorbed on it. When surfactant concentration at the interface reaches a critical value, a surfactant layer is formed at the interface (State III), whereupon, potential at interface o/wl suddenly shifts to more negative values, corresponding to the lower potential of oscillation. With change in interfacial tension of the interface, the transfer and adsorption of surfactant ions is facilitated, with consequent fluctuation in interface o/ wl and convection of phases o and wl (State IV). Surfactant concentration at this interface consequently decreased. Potential at interface o/wl thus takes on more positive values, corresponding to the upper potential of oscillation. Potential oscillation is induced by the repetitive formation and destruction of the DS ion layer adsorbed on interface o/wl (States III and IV). This mechanism should also be applicable to oscillation with CTAB. Potential oscillation across the octanol membrane with CTAB is induced by the repetitive formation and destruction of the cetyltrimethylammonium ion layer adsorbed on interface o/wl. Potential oscillation is induced at interface o/wl and thus drugs were previously added to phase wl so as to cause changes in oscillation mode in the present study. 

Phospholipids are amphiphilic substances i.e. their molecules contain both hydrophilic and hydrophobic groups. Above a certain concentration level, amphiphilic substances with one ionized or polar and one strongly hydrophobic group (e.g. the dodecylsulphate or cetyltrimethylammonium ions) form micelles in solution these are, as a rule, spherical structures with hydrophilic groups on the surface and the inside filled with the hydrophobic parts of the molecules (usually long alkyl chains directed radially into the centre of the sphere). Amphiphilic substances with two hydrophobic groups have a tendency to form bilayer films under suitable conditions, with hydrophobic chains facing one another. Various methods of preparation of these bilayer lipid membranes (BLMs) are demonstrated in Fig. 6.10. 

Takeuchi et al. [343] described an indirect photometric detection method for anions in micro high performance liquid chromatography. Micro anion exchange octadecylsilica columns permanently coated with the hydrophobic cetyltrimethylammonium ion (cetrimide) were used in the high performance liquid chromatography of chloride, nitrate... 

The above approach can be considered as the bottom-up methodology. The top-down approach[208] has also been reported. Hexagonal mesostructured MSU-Z was made through the base hydrolysis of ZSM-5 in the presence of cetyltrimethylammonium ions. The five-membered ring subunits can be readily incorporated into the framework walls of MSU-Z. 

At pH values between 2 and 10, Fe(III) forms ternary complexes with Eriochrome Cyanine R (ECR) and cetyltrimethylammonium ions (CTA). Chrome Azurol S (CAS) and some cationic surfactants (e.g., cetylpyridinium ion, Zephiramine) give similar reactions. These ternary complexes are a basis of sensitive methods of determining Fe(III) [46-53],... 

Silver(I) yields a primary dithizone complex (19 in reaction 1) at low pH, Amax 460 nm, e 30500 (in CCI4)87. This complex in the presence of cetyltrimethylammonium ions has 3-max 565 nm, e 55000 (in H20)99. Instead of densitometry of Ag deposited on X-ray film images and other gel matrices, analysis can be carried out by dissolution with nitric acid, neutralization, LLE with a dithizone solution and spectrophotometric determination X 600 nm, e 32800100. 

If cetyltrimethylammonium ion formed micelles, and one employed it for MEKC, in which direction (towards the cathode or anode ) would ... 

Organogels can be prepared by cationic gemini (dimeric) surfactants as ion pairs with dianions. Hue et al. prepared ion pairs 2a-d consisting of dimers of cetyltrimethylammonium ions with various counteranions (Fig. 4.2b(i)) [11]. Ion pairs 2a,b formed gels in CH2CI2, CHCI3, and CHCI2CHCI2 ( 10 mM). In these... 

Figure 4.18.. Flocculation of silica particles Bridging by (1), cationic surfactant micelles (for example, cetyltrimethylammonium ions) (2) cationic three-dimensional polymer molecules (for example, cationic starch) (3) cationic linear polymers (for example, polyethylene imine.)...

Turning to the second question, it is obvious that the effect of the solvent can be extremely important. Results for the conventional surfactant cetyltrimethylammonium bromide (CTAB) provide a good example of this effect on the equilibrium and dynamic properties of surfactant micelles. The reported cmc and micelle aggregation number of CTAB are respectively about 0.9 mM and 100 in water and 100 mM and less than 10 in formamide. The residence time of a cetyltrimethylammonium ion in its micelle can be estimated to be of the order of 0.1 ms in water and 0.1 is in formamide (see Chapter 3, Section III). Block copolymers are expected to show comparable changes. 

Micellar liquid chromatography is the use of a surfactant such as sodium dodecyl sulfate (SDS) in the mobile phase at a concentration above the critical micelle concentration (CMC) of about 10 M. At the CMC, aggregation of60-100 surfactant monomers occurs with the hydrophobic part of the molecule oriented toward the center of the assembly and the hydrophilic tail exposed to the solution. Other surfactants used have been cationic or nonionic in nature, such as cetyltrimethylammonium ion and Brij-35, respectively. For reversed-phase HPLC, the surfactant can... 

Romsted, L.S. Quantitative treatment of benzimidazole deprotonation equilibria in aqueous micellar solutions of cetyltrimethylammonium ion (CTAX, X = Cl, Br and NO3 ) surfactants. 1. Variable surfactant concentration. J. Phys. Chem. 1985, 89(23), 5107-5113. 

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