Lithium Dodecyl Sulfate Micelles Research Articles

Stepwise elusion method in micellar electrokinetic chromatography via sequential use of lithium perfluorooctadecyl sulfonate and lithium dodecyl sulfate

An effective stepwise micellar electrokinetic chromatography (MEKC) elution method was developed using lithium perfluorooctadecyl sulfonate (LPFOS) and lithium dodecyl sulfate (LDS). The hydrogen-bonding property of LPFOS micelles differs from that of LDS micelles, which leads to remarkably different selectivity in the transfer of solutes to the micelles. The present stepwise method is performed by replacing the inlet reservoir of a first running solution containing LPFOS with that of a second running solution containing LDS during a single separation run in the absence of electroosmotic flow under acidic conditions, where LPFOS micelles work as carriers in first and then LDS micelles turn over. Effective separation of 15 nonionic aromatic compounds was controlled well by adjusting the time in the inlet reservoir, which could not be accomplished with systems using only LPFOS or only LDS, with significant changes in the elution order where necessary. Furthermore, separations with the present stepwise method were easily simulated, and the replacement time was optimized for 3.1min from a 70.0mM LPFOS solution to a 67.5mM LDS solution with nearly complete separation within 15min using the simulated parameters.

Effect of tetraalkylammonium salts on the micellar behavior of lithium dodecyl sulfate: A conductometric and tensiometric study

The effect of quaternary ammonium bromides R 4NBr (R = H, CH 3, C 2H 5, C 3H 7 and C 4 H 9) on the micellar properties of lithium dodecyl sulfate (LDS) micelles has been studied by conductometric and tensiometric techniques. The degree of the conuterion binding, β, is found to increase with the increasing size of the alkyl chain length of the tetraalkylammonium salts. The thermodynamics of micelle formation of ionic surfactant LDS in the presence of 0.001M of different quaternary salts have been thoroughly assessed by the critical micelle concentration (CMC) measurement in the 288.15–318.15K-temperature range at 10K intervals conductometrically. Results show a shallow minimum of the CMC values typically between 300 to 305K for LDS micelles in presence of various salts. The standard free energy of micellization, Δ G 0 m has been found to decrease upon growth of temperature. The standard enthalpy change on aggregation was calculated by using the Gibbs–Helmholtz equation. Tensiometric results show a significant reduction in the solution surface tension with increasing electrolyte concentration. The surface excess of LDS and its minimum area at the air–water interface in the presence of different R 4NBr environment has been determined. The micellar solution of LDS has been found to exhibit a cloud point phenomenon in the presence of Bu 4NBr. The occurrence of cloud point phenomenon is accounted for in terms of the penetration of butyl chains at the surface layer of one micelle into another due to the hydrophobic effect.

Structure and Interaction of Lithium Dodecyl Sulfate Micelles in the Presence of Li-Specific Macrocyclic Cage: A Study by SANS

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructure and Interaction of Lithium Dodecyl Sulfate Micelles in the Presence of Li-Specific Macrocyclic Cage: A Study by SANSY. C. Liu, P. Baglioni, J. Teixeira, and S. H. ChenCite this: J. Phys. Chem. 1994, 98, 40, 10208–10215Publication Date (Print):October 1, 1994Publication History Published online1 May 2002Published inissue 1 October 1994https://doi.org/10.1021/j100091a041RIGHTS & PERMISSIONSArticle Views134Altmetric-Citations33LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (715 KB) Get e-Alerts

Electron spin resonance and proton matrix electron nuclear double resonance studies of N,N,N',N'-tetramethylbenzidine photoionization in sodium and lithium dodecyl sulfate micelles: structural effects of crown ethers

The study of model membrane systems enjoys increasing attention within the area of solar energy research. An electron nuclear double resonance and electron spin resonance study of photogenerated N,N,N[prime],N[prime]-tetramethylbenzidine (TMB) cation in frozen suspensions of lithium (LDS) and sodium (SDS) dodecyl sulfate micelles containing various concentrations of cyclic polyethers was undertaken. The relative location of the TMB cation within the organic aggregate was determined from the proton matrix ENDOR line width at 142 K. A broader line width was observed in LDS compared to SDS micelles, which is due to the fact that the larger lithium cation opens the micellar interface resulting in increased hydration and deeper solubilization of TMB. The proton matrix ENDOR line width decreased upon addition of crown ethers. This decrease may be explained by displacement of the TMB toward the interface as a result of the decrease in ionic strength caused by the complexation of the countercations. The photoyield shows a slight increase with addition of crown ethers. This increase is most likely caused by the increase in the effective anionic charge of the micelle effected by the complexation of the sodium or lithium ions by the crown ethers. This increase in the anionic charge mitigatesmore » the rate of thermal back electron transfer resulting in an increased photoyield. 54 refs., 6 figs., 2 tabs.« less

Structure and aggregation of lithium dodecyl sulfate micelles in the presence of a macrocyclic cage : a SANS study

At pH=12, a macrocyclic cage CESTO is a neutral molecule known to complex Li + in aqueous solution. We study the effect of addition of CESTO on the aggregation behavior of lithium dodecyl sulfate (LDS) by small angle neutron scattering. In aqueous solutions the LDS molecules form micelles of quasi-spherical shape with aggregation number of 90 and fractional ionization of 18%. Upon addition of 0.5 to 1 and 1 to 1 molar ratios of CESTO to the solutions, the aggregation number increases but the ionization reduces due to the complexation of lithium ions by CESTO. This is also accompanied by the decrease of hydration number on the micellar surface

Photoionization in micelles: Addition of charged electron acceptors

The relative photoyield of the electron donor N, N, N′, N′-tetramethylbenzidine (TMB), solubilized in sodium and lithium dodecyl sulfate micelles with added charged electron acceptors was investigated. It was attempted to control the acceptor distance from a charged micellar interface by differently charged acceptors, cationic dimethyl viologen and anionic ferricyanide. However, back electron transfer from both cationic and anionic acceptors was found to be efficient. Thus simple electrostatic arguments for control of the photoyield do not seem applicable. Salt effects associated with the added ionic acceptors which partially neutralize the ionic micellar interface are suggested to be an important factor.