Surfactant nonionic compounds

In MEKC, mainly anionic surface-active compounds, in particular SDS, are used. SDS and all other anionic surfactants have a net negative charge over a wide range of pH values, and therefore the micelles have a corresponding electrophoretic mobility toward the anode (opposite the direction of electro-osmotic flow). Anionic species do not interact with the negatively charged surface of the capillary, which is favorable in common CZE but especially in ACE. Therefore, SDS is the best-studied tenside in MEKC. Long-chain cationic ammonium species have also been employed for mainly anionic and neutral solutes (16). Bile salts as representatives of anionic surfactants have been used for the analysis of ionic and nonionic compounds and also for the separation of optical isomers (17-19). 

Sodium benzoate Antimicrobial preservative tablet and capsule lubricant Nonionic surfactants, quaternary compounds, gelatin, ferric salts, calcium salts and salts, of heavy metals, including silver, lead, and mercury... 

The solubilization of nonionic compounds by surfactants can dramatically affect the sorption of these compounds to soil (Vigon and Rubin 1989 Smith et al. 1991). Vigon and Rubin (1989) determined that anthracene sorption from nonionic surfactant solutions above CMC was two... 

Liu and colleagues found that they could switch between the two forms of s-surf by changing the gas that they bubbled through a solution of the surfactant. They demonstrated this switch by measuring the electrical conductivity of the s-surf solution aqueous solutions of ionic compounds have higher conductivity than solutions of nonionic compounds. They started with a solution of the ami-dine form of s-surf in water. Their results are shown below dotted lines indicate the switch from one gas to another. 

Add sample to column and slowly aspirate through. Anionic surfactant sorbs by anion exchange. Nonionic compounds pass through in methanol. Elute anionic surfactants with 50 50 methanol 0.1 A NaOH, 3 mL. 

Table 5-2 lists some experimental values of Tm, CMC/C2o and jicmc. The experimental tiCmc values are very close to those calculated from the Tm and CMC/C2o values and equation 5.1. For surfactants with hydrocarbon-chain hydro-phobic groups, the most effective surface tension reducers (largest IIcmc values) are (1) nonionic compounds having small hydrophilic head groups and (2) anionic-cationic salts where both hydrophobic chains contain six carbon atoms or more, especially when both chains are approximately of the same length. Because of the... 

Shi, Y. and J.S. Fritz. 1995. HPCZE of nonionic compounds using a novel anionic surfactant additive. Anal. Chem. 67 3023-3027. 

Nonionic surfactants are compounds soluble in both acidic and alkaline media that do not undergo dissociation in aqueous solutions. As a rule, these compounds are the products of ethylene oxide addition to various substances with developed hydrocarbon chains, namely oxyethylenated primary and secondary fatty alcohols, R0(CH2CH20) H, R(R )CH0(CH2CH20) H, polyethyleneglycol esters of fatty acids, RC00(CH2CH20) H, and oxyethylenated alkylphenols,... 

Hypercrosslinked biporous Isolute ENV4- was involved in the analysis of alkylphenolic pollutants [241]. Being the degradation products of nonionic surfactants, these compounds were found to induce a hormonal imbalance in fish. A high extent of enrichment achieved in the off-line preconcentration from 1 L samples and recoveries close to 100% permitted the determination of 4- -hexylphenol, 4-ieri-octylphenol, 4- -heptylphenol, n-nonylphenol, and 4- -octylphenol at the 0.1 Xg/L level. 

The necessity for an adequate experimental design becomes especially important when dealing with forms of liquid chromatography suitable for the simultaneous analysis of ionic and nonionic compounds, such as MLC, where several variables should be controlled i.e., type and concentration of surfactant and organic modifier, pH, temperature and ionic strength). The method development strategy must provide the chromatographer with an answer to which variables (factors) should be used, and how... 

The many interactions that the solutes experience in a micellar chromatographic system enhances the differences among them. The possibility of using, simultaneously, the three most significant variables that affect the retention (j. e., pH, and concentrations of surfactant and modifier), will improve the capability of resolution of complex mixtures of ionic and nonionic compounds. The high accuracy in the prediction of retention factors in MLC permits the reliable and relatively rapid optimization of the composition of the mobile phase for the separation of a mixture of compounds, by using an interpretive method and a reduced number of mobile phases (at least two for one variable, four or five for two variables, and nine for three variables). 

Nonionic Surfactant. The compound C,H, C,H40(CHaCH,0)iCH,CH,0H was claimed by Gabor et al. (380) to act as an inhibitor of silicosis when inhaled by rats. Since experience shows that polyethers of this type are strongly adsorbed by the silica surface, its action may be similar to that of PVPNO. 

Another paper reported on the synthesis, surface-active properties, and micellar aggregation of alkyl 2-amino-2-deoxy-(5-D-glucopyranosides with -alkyl chain lengths of 8, 9, and 12 carbon atoms [118]. Surface tension measurements were performed at 25, 37, and 60°C because the Krafft temperature of the Cu compound was 54°C. Like other nonionic saccharide-based surfactants, the compounds did not show a cloud point. The determined CMCs decreased with alkyl chain length increase, and did not depend on the temperature. The Tmin values were close to 50 x 10 m, ... 

Figure 8 The iV-dodecanoyl-iV-methylglucamine-water system, which illustrates the classical sequence of changes in the solubility boundary with temperature found in many nonionic and ionic surfactants. This compound is somewhat unusual in that the lamellar liquid-crystal phase extends to 100% and so exists as a thermotropic liquid crystal, which melts to an isotropic liquid at about 121 C. Physical studies in this temperature region are compromised by chemical instability. (From Ref. 91.)...

Surfactants may be ionic or nonionic compounds containing ethylene oxide groups. Because the solid content of aqueous PEDOT PSS dispersions is usually rather low (between 1.5% and 4%) surfactants need to be highly effective at extremely low concentrations. For example, a surfactant that has been added to a PEDOT PSS coating formulation at a concentration of 1% total of the formulation will yield as much as 40% of the solids of the final, dried film. 

Nonionic surfactants—do not dissociate into ions, for example, C7Fi5CH2CH20(CH2CH20) H. a special class of nonionic fluorinated surfactants are compounds which do not have a hydrophile but consist of an oleophobic (fluorinated) segment and a oleophilic segment (see Section 1.8). 

The rapid growth in the availability of alternate raw materials after World War 11 led to the development of well-characterized synthetic surface-active materials to meet the needs of the new technological world. Because of their utility and relative ease of manufacture, the sulfate and sulfonate surfactants continue to lead the way, although many classes of ionic and nonionic compounds have been investigated and developed in the hope of finding a super surfactant with the surface activity and economic attractiveness needed to dominate a large portion of the market for such materials. The literature on the development of new surfactants, both academic and industrial, represents a wealth of useful knowledge for the surfactant chemist or the user in need of a solution. 

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