Surfactant polyoxyethylene 23-lauryl ether

FIGURE 12.2 Normalized enzymatic activity of HLAD in aqueous 1-pentanol solutions as a function of added surfactant (polyoxyethylene(23)lauryl ether [C12EO23]). The vertical dashed line denotes the cmc of the pure surfactant. From top to bottom alcohol concentrations of 10", 5 X10", 7.5 X10", and 10" M. (From Schirmer, C., PhD Thesis, University of Regensburg, Germany, 2001.)... 

Materials that are solubilized in polyethylene glycol can be solubilized in the polyoxyethylene chains on the surface of a nonionic micelle. Ismail, Gouda, and Motawi found that the micellar partition coefficients of barbiturates in polysorbates 20, 40, 60, and 80 is a function of the solute substituents and is proportional to the octanol-water partition coefficient of the barbiturate. Similarly, Ikeda, Kato, and Tukamoto showed that the solubilization of alkyl barbiturates by polyoxyethylene lauryl ether is not dependent upon the number of carbons in the substituents. Since the different polysorbates contain different aliphatic groups, the rather small dependence of solubilization upon polysorbate number (i.e., upon alkyl chain length) suggests that the barbiturates are not solubilized primarily in the hydrocarbon portion of the micelle. Gouda, Ismail, and Motawi showed that the solubilization of barbiturates in polyoxyethylene stearates is proportional to the number of polyoxyethylene units in the surfactant. 

In these studies, the system water/Brij 30 (polyoxyethylene lauryl ether with an average of 4mol ethylene oxide/decane) was chosen as a model to obtain O/W emulsions. The results showed that nanoemulsions with droplet sizes on the order of 50 nm were formed only when water was added to mixtures of surfactant and oil (method B), whereby an inversion from a W/O emulsion to an O/W nanoemulsion occurred. 

In SPE, a small amount of organic solvent or surfactant is added to collected samples to prevent adsorption to sample containers. To increase recoveries of ng 1 levels of PAHs in SPE, ACN (40%) or surfactants above their CMC can be added to samples prior to preconcentration. Solid supports, chemically modified with copper phthalocyanine trisulfonic acid derivatives for selective sorption of PAHs, have been investigated. The selective interaction is thought to be with the tt electrons of the PAHs. Brij-35, a neutral polyoxyethylene lauryl ether surfactant was added above the CMC to water samples to prevent sorption on container walls. Before preconcentration by SPE, samples were diluted to reduce the surfactant concentration to just below the CMC. Recoveries of over 90% for SPE on solids containing copper phthalocyanine trisulfonic derivatives were obtained for spiked water samples at low ngl levels, except for NAP, ACE, and FLU. Experiments repeated using a C18 SPE preconcentration sorbent gave >90% recovery for all 16 EPA PAHs, except for ACY. Examples of the use of SDB as an SPE sorbent include the online analysis of seawater from the coast of Catalonia in Spain, where no PAHs above the low ng 1 level were detected, and the analysis of leachate from coal deposits. ... 

The acid catalysed degradation of penicillins is inhibited in cationic micelles of cetyltrimethylammonium bromide (Tsuji et al., 1982) and, as expected, neither anionic micelles of sodium dodecylsulphate nor polyoxyethylene lauryl ether promote the hydroxide-ion catalysed hydrolysis of benzylpenicillin (Gensmantel and Page, 1982a). In the presence of cetyltrimethylammonium bromide (CTAB) the pseudo first-order rate constants for the alkaline hydrolysis increase rapidly with surfactant concentration once... 

Asgher et al. (2011b) have also reported another FI-CL method to determine retinol and a-tocopherol in pharmaceuticals and human blood serum based on the enhancement effect of the lucigenin CL reaction in alkaline medium. Surfactants including polyoxyethylene lauryl ether (Brij-35), Triton X-100, cetyltrimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) enhance lucigenin CL intensity. With Brij-35, the enhancement was 67% for retinol and 58% for a-tocopherol. With CTAB, the enhancement was 16% for retinol whereas for a-tocopherol, the CL intensity was quenched by up to 95%. Retinol could be determined specifically in the presence of a-tocopherol using CTAB. 

A wider range of 34 benzoic acid derivatives has been studied in detail by Tomida et al. [27]. Using a solubility method these workers obtained saturation solubilities of the benzoic acid derivatives in Brij 35 (a polyoxyethylene lauryl ether) over a range of concentrations. Solubility ratios, calculated as the solubility in the surfactant solution/solubility in HCl, were a linear function of surfactant concentration allowing the calculation of a partition coefficient Pm which can be defined as... 

Figure 1.4 Plots of the interfacial tension of corn oil/surfactant solutions and detergency as a function of the number of glycerol or oxyethylene (EO) units of polyglycerol laurate (filled symbols) and polyoxyethylene lauryl ether (open symbols).

Conjunctival insulin absorption in rabbits estimated as plasma insulin levels after punctal occlusion was also shown to be increased by bile salts (sodium deoxycholate, glycocholate, and taurocholate) and a surfactant (polyoxyethylene-9-lauryl ether) [200], Their rank order of effectiveness at 1% was sodium deoxycholate > polyoxyethylene-9-lauryl ether > sodium glycocholate = sodium taurocholate. There was an 18-, 29-, 3-, and 3-fold increase, respectively, in conjunctival absorption. Sodium deoxycholate, a dihydroxy bile salt, was more effec-... 

The addition of absorption enhancers, like bile salts (glycocholate), fatty acids (Unoleic acid), surfactants (lecithins, polyoxyethylene-9-lauryl ether or N-lauryl-P-D-maltopyra-noside) and chelators (EDTA) can significantly increase the absorption of various proteins. However, the application of enhancers is limited by their toxicity. For example polyoxyethyl-ene-9-lauryl ether and sodium glycocholate caused serious oedema, haemorrhage and inflammation of the lung after intratracheal instillation [39]. 

Figure D3.5.6 Adsorption kinetics of a small molecule surfactant. Surface tension of polyoxyethylene (10) lauryl ether (Brij) at the air-water interface decreases as time of adsorption increases. Brij concentration is 0.1 g/liter, as measured by the drop volume technique and the maximum bubble pressure method (UNITD3.6).

All density gradient separations are carried out in aqueous cesium chloride solutions to which a nonionic surfactant has been added (polyoxyethylene-23-lauryl ether, Brij-35). The surfactant is necessary to disperse the fine coal particles in the aqueous medium. Without complete particle dispersion the separation will most likely not be optimal. 

All of the samples prepared by centrifugation and the float-sink method were demineralized and milled to three micron diameter. The separations were conducted in the presence of a surface active agent, polyoxyethylene(23) lauryl ether, in cesium chloride solutions (14). The macerals were washed thoroughly to reduce the quantity of surfactant in the maceral to less than 500 ppm and the quantity of chloride ion in the wash water to below the limit detectable by precipitation with silver ion (14). 

The hydrolysis at 25 °C of p-nitrophcnyl picolinate (71) catalysed by the Cu(II) complex of 4-chloro-2,6-di(iV-hydroxyethylaminomethyl)phenol (72 R = CH2NH CH2CH2OH) was studied kinetically at different pH in the presence of three surfactants hexadecyltrimethylammonium bromide, sodium lauroylsarcosinate, and polyoxyethylene (23) lauryl ether.69 The Cu(II) complexes of two iV-alkyl-3,5-di(hydroxy-methyl)-1,2,4-triazoles (73 R = CioH2i, Ci2H2s) were better than the Ni(II) complexes as catalysts for the hydrolysis of p-nitrophcnyl picolinate (71) in CTAB micelles.70... 

Surfactants Sodium lauryl sulfate, saponin, polyoxyethylene-9-lauryl ether, polyoxyethylene-20-lauryl ether, alkylmaltosides such as tetradecylmaltoside, dodecylmaltoside, and decylmaltoside Membrane disruption... 

Surfactants Sodium lauryl sulfate Polyoxyethylene oxide-9 ethers Solubilization of proteins/peptides Perturbation of membrane layers Extraction of membrane proteins and lipids... 

Gluten was obtained from ProVim, a gluten-enriched flour, by a conventional dough-and-wash procedure (16). Gliadin was separated from the gluten by the method of Jones et al. (17). The surfactants selected for study were Myrj 45 [polyoxyethylene (8) stearate], Tween 60 [polyoxyethylene (20) sorbitan monostearate], Brij 35 [polyoxyethylene (23) lauryl ether], Brij 76 [polyoxyethylene (10) stearyl ether], Brij 78 [polyoxyethylene (20) stearyl ether], and calcium stearoyl-2-lactylate. (Note that the numbers in parentheses indicate the number of monomer units of ethylene oxide.) Working solutions were made up in 70% ethanol at 2.5 mg per 100 ml solution. 

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