Lithium Perfluorooctanesulfonate Research Articles

A perfluorinated micellar reaction system in lithium perchlorate/acetonitrile; enhanced efficiency in anodic electron-transfer and intermolecular cycloaddition

A micellar electrolytic reaction system composed of lithium perfluorooctanesulfonate (LiFOS), highly concentrated lithium perchlorate in acetonitrile, effectively dispersed slightly soluble compounds to promote anodic electron transfers, and it further accelerated the formation of desired cycloadducts between electrogenerated quinones and dienes.

Physicochemical properties of aqueous mixed solutions of sugar-persubstituted poly(amidoamine)dendrimers and anionic surfactants

Mixed aqueous properties of sugar-persubstituted poly(amidoamine) dendrimers (generation, 3.0 and 5.0) (sugar ball) and anionic surfactants, such as sodium dodecyl sulfate (SDS) and lithium perfluorooctanesulfonate (LiFOS), were investigated. The surface tensions of the mixtures of sugar balls and anionic surfactants at several fixed concentrations of sugar balls decreased sharply at low surfactant concentration, remained constant and then increased with a further increase of the surfactant concentration where the lower the surface tensions, the smaller the fixed concentration of the sugar balls. From the measurements of pyrene and 1-(perfluorooctanoyl)pyrene fluorescence spectra, it is suggested that aggregates between the anionic surfactants and sugar balls are formed, showing a hydrophobic environment. The mechanism for the aggregation formation is discussed.

Solute–solvent interactions in micellar electrokinetic chromatography: Selectivity of lithium dodecyl sulfate–lithium perfluorooctanesulfonate mixed-micellar buffers

The solvation parameter model has been applied to the characterization of micellar electrokinetic chromatographic (MEKC) systems with mixtures of lithium dodecyl sulfate and lithium perfluorooctanesulfonate as surfactant. The variation in MEKC surfactant composition results in changes in the coefficients of the correlation equation, which in turns leads to information on solute–solvent and solute–micelle interactions. Lithium perfluorooctanesulfonate is more dipolar and hydrogen bond acidic but less polarizable and hydrogen bond basic than lithium dodecyl sulfate. Therefore mixtures of lithium dodecyl sulfate and lithium perfluorooctanesulfonate cover a very wide range of polarity and hydrogen bond properties, which in turn results in important selectivity changes for analytes with different solute properties.

Simultaneous Adsorption of Sugar-Persubstituted Poly(amidoamine) Dendrimers and Anionic Surfactant at the Alumina/Aqueous Solution Interface

The simultaneous adsorption of sugar-persubstituted poly(amidoamine) dendrimers (sugar ball) and anionic surfactants such as sodium dodecyl sulfate (SDS) and lithium perfluorooctanesulfonate (LiFOS) on positively charged alumina particles was investigated at pH 3.5 by measuring the amount of adsorbed sugar ball and anionic surfactant, ζ potential, and sedimentation rate of alumina suspensions. The sugar balls of generations G3 and G5 were used. Under constant initial concentrations of the sugar balls, the amount of adsorbed sugar balls sharply increases, reaches a maximum, and then decreases, while the anionic surfactant adsorption increases with increasing anionic surfactant. The enhancement in the adsorption of the sugar balls is due to the adsorption of complexes consisting of sugar ball and anionic surfactant. In addition, the dispersion stability of alumina suspensions caused by the adsorption of the sugar ball and anionic surfactant depends on the ζ potential of alumina as well as the adsorption of ...

Interactions of Sugar-Persubstituted Poly(Amidoamine) Dendrimers with Anionic Surfactants

The interactions of sugar-persubstituted poly(amidoamine) dendrimers (generation, 3.0 and 5.0) (sugar ball) with anionic surfactants such as sodium dodecyl sulfate (SDS) and lithium perfluorooctanesulfonate (LiFOS) were investigated at a constant concentration of the sugar ball. At low surfactant concentrations, aggregates of the anionic surfactants at the surface of the sugar ball are formed, showing a strong surface activity. The size of the mixed aggregates increases with the anionic surfactant concentration, and also depends on the generation of the sugar ball: the size for generation 3.0 is greater than that for generation 5.0. The association process is also affected by the kind of hydrophobic chain of the surfactant. These differences reflect solubilization behaviors of biphenyl and decafluorobiphenyl into the mixed systems of the sugar ball and the surfactant.

Recommendations for the determination of selectivity in micellar electrokinetic chromatography

A general approach for characterizing selectivity in micellar electrokinetic chromatography based on the solvation parameter model is recommended. Individual surfactants are characterized by their cohesion and capacity for polar interactions indicated as lone pair–lone pair electron attraction, dipole-type interactions, and hydrogen bond acidity and basicity. The statistical and chemical validity of the solvation parameter model requires that retention data are determined for a collection of 20–40 varied solutes with a wide range of retention factors and that clustering of values and cross-correlation among the solute descriptors are absent. Since micelles are interfacial solvents with properties that can vary with changes in their external environment (buffer composition, concentration, pH, temperature, etc.) a generic set of experimental conditions are recommended for the measurement of anionic surfactant selectivity under standard conditions. The system constants used to characterize surfactant selectivity are calculated for 12 common surfactants used in micellar electrokinetic chromatography. Of these surfactants sodium dodecyl sulfate, sodium cholate, lithium perfluorooctanesulfonate, sodium N-dodecanoyl-N-methyltaurine and tetradecyltrimethylammonium bromide are identified as providing a useful range of selectivity differences for methods development in micellar electrokinetic chromatography.

Does participation in clinical trials prolong hospitalization?

The solubilization of hydrocarbon and fluorocarbon alcohols in single and mixed aqueous solutions containing fluorocarbon surfactant has been studied. Surfactants used are lithium dodecyl sulfate (LiDS), lithium perfluorooctane sulfonate (LiFOS), lithium perfluorooctanoate (LiPFO), and hexaethyleneglycol dodecyl ether (6ED). In single surfactant systems, the partition coefficients of the alcohols between anionic micelles and water are greater for the surfactants which have the same kind of alkyl chain as the alcohols than for the surfactants having a different kind of alkyl chain to the alcohols. The standard free energies calculated from the partition coefficients indicate that the transfer of the alcohols occurs more favorably to the micelles consisting of the same kind of alkyl chain as the alcohols than of the different kind of alkyl chain. Also, the mixed surfactant systems LiDS-LiFOS, LiFOS-LiPFO and 6ED-LiFOS have been characterized by the regular solution parameter β and the alcohol partition coefficient. In the LiDS-LiFOS system with a positive β value, the partition coefficients of both hydrocarbon and fluorocarbon alcohols are greater than in single surfactant systems. In the LiFOS-LiPFO system exhibiting almost ideal mixing, the partition coefficients of both hydrocarbon and fluorocarbon alcohols change ideally, whereas the partition coefficients of the fluorocarbon alcohols are greater than those of the hydrocarbon alcohols. By contrast, in the 6ED-LiFOS system with negative β values, the partition coefficients of both alcohols are lower than in single surfactant systems.

Mixed Micellar Properties of Nonionic Saccharide and Anionic Fluorocarbon Surfactants in Aqueous Solution

Mixed micellar properties of nonionic saccharides (n-decyllactobionamide, C10Glu2;n-dodecyllactobionamide, C12Glu2) and anionic fluorocarbon surfactants (lithium perfluorooctanesulfonate, LiFOS) in aqueous solutions have been studied by means of surface tensiometry, NMR, and light scattering. The interaction parameters estimated from the modified regular solution theory are −5.0 for the C10Glu2/LiFOS system and −0.2 for the C12Glu2/LiFOS system. This difference could be due to the interaction of the surfactant tails. The average aggregation number is almost identical over a wide mole fraction of C12Glu2for the C12Glu2/LiFOS system, while it shows a minimum at a C10Glu2mole fraction of 0.4 for the C10Glu2/LiFOS system. It is also found from NMR measurements that the segmental motions of surfactants in the mixed micelles of C12Glu2and LiFOS are not restricted, whereas they are restricted at a C10Glu2mole fraction of 0.4 for the C10Glu2/LiFOS system. These motional changes as well as micellar composition reflect the solubilization of decafluorobiphenyl in the mixed micelles.

Organized Structure of Lithium Perfluorooctanesulfonate at the Graphite–Solution Interface

The structure of aggregates of lithium perfluorooctanesulfonate (LiFOS) adsorbed to the interface between graphite and aqueous solution have been measured. This fluorocarbon surfactant produces aggregates which are long (∼100 nm) and thin (∼5 nm), and about one molecule (∼1.3 nm) deep. The aggregates lie in straight, parallel arrays on the surface with a characteristic repeat distance, or period, perpendicular to the long axis. As the bulk concentration of LiCl is increased, the period decreases, but as the bulk concentration of LiFOS is increased, the period increases. The decrease in period on addition of salt is similar to that observed for sodium dodecyl sulfate (SDS) and is explicable in terms of electrostatic forces. The increase in period on addition of surfactant is in sharp contrast to the behavior of SDS and may be due to a higher surfactant packing-parameter for LiFOS.

Simultaneous adsorption of poly(N-vinyl-2-pyrrolidone) and [formula omitted] surfactant from their binary mixtures on [formula omitted] silica

The simultaneous adsorption of lithium dodecyl sulfate (LiDS)/lithium perfluorooctanesulfonate (LiFOS) and poly(N-vinyl-2-pyrrolidone) (PVP) from PVP-LiDS and PVP-LiFOS binary mixed aqueous solutions on hydrophilic hydrophobic silica was investigated. The conformation and layer thickness of PVP adsorbed on silica were also estimated by using ESR and photon correlation spectroscopy (PCS), respectively. By introducing a sedimentation field-flow fractionation (sedFFF) separation step prior to the PCS sizing to fractionate the adsorbate into cuts of uniform particle size, it is possible to improve the accuracy in these size measurements. The adsorption of PVP is enhanced in the presence of LiDS at low LiDS concentration owing to the formation of a surface complex of PVP and LiDS, followed by a decrease at high LiDS concentration. However, this increment on hydrophobic silica is significantly greater than that on hydrophilic silica. A similar trend is also observed in the PVP-LiFOS system. In both the PVP-LiDS and PVP-LiFOS systems, the conformation of PVP adsorbed, in particular on hydrophilic silica, is changed remarkably from loops and tails to trains with the surfactant concentration. The results obtained from ESR show a good relationship with the thickness of PVP adsorbed obtained from PCS.

Chemical selectivity in micellar electrokinetic chromatography II. Rationalization of elution patterns in different surfactant systems

Retention behavior in micellar electrokinetic chromatography (MEKC) is investigated using linear solvation energy relationships (LSERs) for two pseudo-stationary phases, one consisting of cationic micelles of tetradecyltrimethylammonium bromide (C 14TAB) and the other of an anionic triblock copolymer, poly(methyl methacrylate-ethyl acrylate-methacrylic acid) (Elvacite 2669). It was found that solutes' migration behaviors in these two MEKC systems are mainly influenced by their si/e ( V/100) and hydrogen bonding acceptor (HBA) strength (β). However, solutes' hydrogen bonding donor (HBD) strength (α) has minor effects on their migration in MEKC. The characteristics of these two systems were compared to three other previously reported anionic micellar systems of sodium dodecyl sulfate (SDS) (anionic hydrocarbon), sodium cholate (SC) (anionic bile salt) and lithium perfluorooctane sulfonate (LiPFOS) (anionic fluorocarbon). It was concluded that hydrogen bonding interactions play a major role in providing different chemical selectivity among these five MEKC systems. Both C 14TAB micelles and the ionic polymer of Elvacite 2669 provide hydrogen bonding acceptor (HBA) sites for solutes, which is similar to SC micelles. In fact, C 14TAB is the strongest HBA, while Elvacite 2669 has HBA strength similar to that of SC micelles. On the other hand, the fluorocarbon micelles of LiPFOS are the strongest hydrogen bond donor (HBD) micelles, followed by the weak HBD SDS micelles. In general, cavity formation has little or no effect on chemical selectivity among hydrocarbon surfactant MEKC systems (i.e., SDS, SC and C 14TAB). Information obtained from the LSER analysis is used to rationalize the elution patterns in MEKC with different types of pseudo-stationary phases.

Mixed micellar properties of octyl-β-d-glucoside and lithium perfluorooctane sulfonate

Abstract Mixed micellar properties of octyl-β- d -glucoside (AG8) and lithium perfluoroonate sulfonate in aqueous solution have been studied. The mixture CMC values are lower than data for ideal mixing, indicating that a favorable interaction in the mixed micelles arises, having the interaction parameter −1.85. The aggregation number of mixed micelles increases gradually until the mole fraction of AG8=0.8 and the increases sharply. A similar change is observed for the micellar radius. Thus, the micellar properties of mixed micelles are markedly affected by incorporation of the fluorocarbon surfactant.

Quantitative structure-activity relationships studies with micellar electrokinetic chromatography influence of surfactant type and mixed micelles on estimation of hydrophobicity and bioavailability

Applications of micellar electrokinetic chromatography (MEKC) in quantitative structure-activity relationships (QSAR) were studied. First, quantitative structure-retention relationships (QSRR), which describe the correlation between logarithm of capacity factor (log k′) in MEKC and logarithm of distribution coefficient between 1-octanol and water (log P ow), were investigated for 60 aromatic compounds and 9 corticosteroids using three different anionic surfactants [e.g., sodium dodecyl sulfate (SDS), sodium cholate (SC), and lithium perfluorooctane sulfonate (LiPFOS)], one cationic surfactant (C 14TAB), and mixed anionic micellar systems. Linear solvation energy relationships (LSER) and solvatochromic parameters were used to shed light on the different log k′ vs. log P ow relationships for the various surfactants. It was concluded that hydrogen bonding interactions have a great influence on retention behavior in MEKC and its relationship with hydrophobicity. Interestingly, bile salt surfactants (e.g., SC) and mixed bile salt micellar systems provide better correlations for log k′ vs. log P ow than SDS and/or SDS with buffer additives (e.g., ß-cyclodextrin, urea, and acetonitrile). Using SC micelles, only one line was adequate to describe the relationship between retention in MEKC and hydrophobicity for a group of 60 aromatic compounds. The existence of higher correlation for the SC system was attributed to a similar hydrogen bonding pattern between SC micelles and 1-octanol. In the SDS system, however, three lines were recognized for the congeneric subgroups of compounds. This is due to the hydrogen bond donor (HBD) characteristics of SDS micelles that selectively differentiate between the solutes with different hydrogen bond acceptor (HBA) strength, thus demonstrating that retention is not solely based on hydrophobicity. A similar result was observed for a C 14TAB-MEKC system, however, the HBA characteristics of C 14TAB selectively differentiates between the solutes with different HBD strength. In addition, quantitative retention-activity relationships in MEKC were also investigated for 9 corticosteroids. Two types of biological activities [small intestinal absorption in the rat (log A/NA) and protein binding to human serum albumin (log B/F)] were examined in this work. High correlations were observed between bioactivity and log k′ in MEKC using bile salt surfactants and mixed bile salt systems.

Effect of Urea on Micelle Formation of Fluorocarbon Surfactants

The effect of urea on micelle formation of fluorocarbon surfactants was investigated by measuring conductivity cmc and fluorescence intensity of probes (1-anilinonaphthalene-8-sulfonate, auramine, and pyrene). We examined various fluorocarbon surfactants which consist of different ionic head groups, i.e., lithium perfluorononanoate (LiPFN), diethylammonium perfluorononanoate (DEAPFN), lithium perfluorooctanesulfonate (LiFOS), and 1H,1H,2H,2H-perfluorodecyl sulfate (LiHFDeS). Significant differences do exist between fluorocarbon and hydrocarbon surfactants ; the cmc's of the fluorocarbons slightly decreased with the addition of urea, while those of the hydrocarbons increased as reported previously. The slight decreases in cmc's of fluorocarbon surfactants were confirmed by comparison with LiDS and LiHFDeS which contain the same ionic head group. The counterion dissociation degree of micelles always increased with the addition of urea. The micropolarities of fluorocarbon micelles were almost identical with the polarity of water, and were independent of urea concentration. The microviscosities of DEAPFN micelles decreased with urea concentration. These results suggest the significant differences in micellar characteristics between fluorocarbon and hydrocarbon surfactants.

Interaction between Poly( N-vinyl-2-pyrrolidone) and Anionic Hydrocarbon/Fluorocarbon Surfactant on Hydrophobic Graphite

The adsorption of poly( N-vinyl-2-pyrrolidone) (PVP), lithium dodecyl sulfate (LiDS), and lithium perfluorooctanesulfonate (LiFOS) from PVP-LiDS and PVP-LiFOS binary mixed solutions on hydrophobic graphite has been investigated by measuring the adsorbed amount, ESR spectra, and ζ potential. The adsorption of PVP is enhanced in the presence of LiDS at low LiDS concentration due to formation of a surface complex of PVP and LiDS, followed by a decrease at high LiDS concentration. However, this increment on hydrophobic graphite is significantly smaller than that on hydrophilic alumina. A similar trend is observed in the PVP-LiFOS system. In both PVP-LiDS and PVP-LiFOS systems, the conformation of PVP adsorbed is estimated using a spin-labeled PVP and is changed gradually from loops and tails to trains with the surfactant concentration. The fraction of train segments in the PVP-LiFOS system is greater than that in the PVP-LiDS system over the whole surfactant concentration region.

Chemical Selectivity in Micellar Electrokinetic Chromatography: Characterization of Solute-Micelle Interactions for Classification of Surfactants

The influence of surfactant type on migration behavior and chemical selectivity in micellar electrokinetic chromatography (MEKC) is investigated through linear solvation energy relationships (LSER) and functional group selectivities. In LSER modeling, solutes' capacity factors are correlated with their structural descriptors such as size, dipolarity, and hydrogen-bonding abilities. Using the LSER methodology, useful information about the nature of solute interactions with different types of surfactant aggregates can be obtained since capacity factor in MEKC is directly related to solute distribution between the bulk aqueous solvent and micelles. High correlations were observed for different LSER models of migration behavior in MEKC for a group of 60 uncharged aromatic compounds of non-hydrogen bonding (NHB), hydrogen-bonding acceptor (HBA) bases, and hydrogen-bonding donor (HBD) acids. In two anionic, hydrocarbon micellar systems of sodium dodecyl sulfate (SDS) and sodium cholate (SC), retention is primarily influenced by the size of molecules and their hydrogen bond accepting basicity. Their dipolarity/polarizability and hydrogen bond donating acidity play minor roles. Capacity factors of solutes in SDS and SC systems increase with their size and decrease for stronger hydrogen bond acceptor bases. These results are similar to those observed for other systems where hydrophobic interactions play a major role, e.g., solute distribution in the 1-octanol-water solvent system or retention in reversed phase LC. In MEKC with an anionic fluorocarbon surfactant, lithium perfluorooctanesulfonate (LiPFOS), however, size and solute HBD acidity are the two predominant factors. The LSER results indicate that compounds find the SDS micellar environments slightly less cohesive (i.e., more apolar) than the SC micelles, while the LiPFOS micelles are the most cohesive among the three surfactant aggregates and 1-octanol provides the least cohesive environment. The fluorocarbon micelles of LiPFOS, on the other hand, are the strongest hydrogen bond donor acids, followed by SDS, SC, and 1-octanol, respectively. The SC micelles have the most hydrogen bond acceptor basic characteristics, followed by 1-octanol, SDS, and LiPFOS micelles. It can be concluded that selectivity differences between these surfactant types in MEKC is primarily due to hydrogen-bonding interactions rather than the dipolar interactions. Comparing the perfluorinated and the hydrocarbon surfactants, even solute size can play a role in selective migration patterns. In addition, information from polar and hydrophobic group selectivities confirm the LSER conclusions about the underlying interactions that control migration behavior and chemical selectivity in MEKC.(ABSTRACT TRUNCATED AT 400 WORDS)

Selectivity control in micellar electrokinetic chromatography of small peptides using mixed fluorocarbon-hydrocarbon anionic surfactants

Electrophoretic mobilities and capacity factors for a group of Trp-containing small peptides were determined by micellar electrokinetic chromatography (MEKC) using mixtures of a fluorocarbon anionic surfactant, lithium perfluorooctane sulfonate, and a hydrocarbon anionic surfactant, lithium dodecyl sulfate. Upon mixing these two surfactants, which have different microenvironments and interactive characteristics, greater control over migration of solutes is achieved. The changes in the composition of mixed micelles such as the mole fraction of the surfactants result in different solute-micelle binding as well as migration times of the micelles ( t mc). Consequently, capacity factor, selectivity and elution window ( t mc/ t 0) change with the composition of the mixed micellar system. Another characteristic of the mixtures of fluorocarbon-hydrocarbon surfactants is the possibility of forming two different types of micelles which offers an additional partitioning process for each solute in the MEKC system. Such a unique phenomenon offers a higher degree of selectivity control. This mixed MEKC system is quite effective for the separation of small peptides. It provides an alternative to the free-solution capillary zone electrophoresis system for the separation of charged solutes with nearly identical electrophoretic mobility.

The interaction between co‐polymer of vinylpyrrolidone and vinylacetate and anionic surfactants in aqueous solutions

AbstractThe interaction of co‐polymers of vinylpyrrolidone‐vinylacetate with anionic surfactants, such as lithium dodecyl sulfate (LiDS), lithium perfluorooctane sulfonate (LiFOS) in aqueous solution, has been studied. When the content of vinylacetate in the co‐polymers increases, reduction in the surface tension of co‐polymers alone becomes significant. In mixtures of co‐polymers and surfactants, co‐polymer‐LiFOS complexes are formed at lower surfactant concentration than that of co‐polymer‐LiDS. The micropolarity of the co‐polymers‐surfactant complexes depends on the composition of co‐polymers and is higher for co‐polymer‐LiFOS than that for co‐polymer‐LiDS. Further, the solubilization behavior of α‐(o‐tolylazo‐)‐β‐naphthylamine (Yellow OB) (Tokyo Kasei Co., Ltd., Tokyo, Japan) in the co‐polymer‐surfactant complexes is almost independent of the co‐polymer composition, but different from the surfactants, where a very low solubilized amount of Yellow OB is observed for co‐polymer‐LiFOS.

Study on the miscibility of lithium tetradecyl sulfate and lithium perfluorooctane sulfonate in the adsorbed film and micelle

The surface tension of the aqueous solution of lithium tetradecyl sulfate (LiTS) and lithium perfluorooctane sulfonate (LiFOS) mixture was measured as a function of the total molality and composition of surfactants at 298.15 K under atmospheric pressure. The compositions in the adsorbed film and micelle were evaluated numerically by applying the thermodynamic equations derived previously. It was found that the adsorbed film is enriched in LiFOS molecules at a small concentration, while it is enriched in LiTS molecules at a large concentration, as compared to the aqueous solution, and both molecules mix nonideally with each other. On the other hand, they were proved to be partially immiscible in the micellar state and to form the two kinds of micelles which coexist in equilibrium only at the composition of the heterogeneous azeotropic (hetero-azeotropic) point. It was also observed that the LiTS molecules expel the LiFOS molecules from the micelles in a composition range where the mole fraction of LiFOS is small. Comparing the above results to those of a lithium dodecyl sulfate (LiDS) and LiFOS mixture, the chain length of hydrocarbon surfactant was concluded to have a considerable influence on the miscibility of hydrocarbon and fluorocarbon surfactants in the adsorbed film and micelle.

Phase behavior and dynamic properties in mixed systems of anionic and cationic surfactants: lithium perfluorooctanesulfonate/diethanolheptadecafluoro-2-undecanolmethylammonium chloride (DEFUMAC) and lithium dodecyl sulfate/DEFUMAC aqueous mixtures

Two ternary phase diagrams of the cationic perfluorosurfactant diethanolheptadecafluoro-2-undecanolmethylammonium chloride (DEFUMAC) with an anionic perfluorosurfactant lithium perfluorooctanesulfonate (LiFOS) and an anionic hydrocarbon surfactant lithium dodecyl sulfate (LiDS) have been established at 25°C. The total surfactant concentration was less than 20wt%. In a wide mixing region of the LiFOS/DEFUMAC system, a lamellar-type phase,Pβ, was identified by its texture under a polarization microscope and by its x-ray diffraction pattern. Dispersed fragments ofPβ-phase are present in the dilute solutions in which one surfactant was in excess. The anisotropy of electrical conductivity, flow birefringence, dynamic light scattering, and electric briefringence demonstrate that thePβ fragments are disk-like with a radius of 0.7 μm. The disk-likePβ particles are transformed by shear into a spherical aggregate ofLα above a critical shear gradient. LiDS/DEFUMAC mixed solution forms dispersed and precipitatedLα in the dominant region. Radius and micropolarity of the dispersedLα aggregates are decreased as the ratio of LiDS:DEFUMAC approaches 1:1. On the basis of x-ray diffraction measurement the structure of precipitatedLα-phase seems to consist of monolayers.