sodium-dodecyl-sulfate and perfluorooctane-sulfonic-acid

In order to elucidate an electroacoustic phenomenon of mixed micelles in an aqueous solution, we measured the colloid vibration current (CVI) in aqueous solutions of binary surfactant mixtures. Based on the thermodynamic treatment of critical micelle concentration (cmc) values determined by conductivity measurements, it was expected that dodecyltrimethylammonium bromide (DTAB) and dodecyltrimethylammonium chloride (DTAC) molecules would mix ideally in the micelle. However, the micelle composition as evaluated from the CVI measurement, based on the linear dependence of the CVI value on the micelle composition, differed from the aforementioned ideality. Considering these observations, we concluded that the CVI measurement was more sensitive to the counterion distribution near the micelle surface, whereas the thermodynamically determined micelle composition included the counterions more loosely bound in the diffuse double layer due to the electroneutrality condition included in its assumption. On the other hand, the phase diagram illustrating micelle formation in the lithium dodecyl sulfate (LiDS) - lithium perfluorooctane sulfonate (LiFOS) mixture system showed a heteroazeotropic point arising from the stronger interactions between homologous surfactants than between heterologous ones. Although the concentration dependence of CVI values was expected to drastically change at a heteroazeotropic point due to the enormous variation in the density of the micelle core, the results showed a monotonous change, which suggests that the density of the micelle core varies continuously. By taking the partial molar volume of fluorocarbon compounds in the hydrocarbon compounds into account, the density of the micelle core was affected by the size of the micelle as well as its constituents.

Topics: Alkanesulfonic Acids; Anions; Colloids; Electric Conductivity; Fluorocarbons; Hydrophobic and Hydrophilic Interactions; Micelles; Molecular Structure; Quaternary Ammonium Compounds; Sodium Dodecyl Sulfate; Surface-Active Agents; Thermodynamics; Ultrasonic Waves; Water

A new paired ion electrospray ionization tandem mass spectrometry method for determination of anionic surfactants in water samples was developed. In this method, dicationic ion-pairing reagents were complexed with monoanionic analytes to facilitate analyte detection in positive mode electrospray ionization - mass spectrometry. Single ion monitoring and selected reaction monitoring on a triple quadrupole instrument were performed and compared. Four dicationic reagents were tested for the determination of perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), sodium dodecyl sulfate (SDS), dodecylbenzene sulfonic acid (DBS), and stearic acid (SA), among other common anions. The obtained limits of detection were compared with those from previous literature. Solid phase extraction using a C18 cartridge was performed in order to eliminate matrix interferences. A literature review was compiled for the methods published between 2010 and 2015 for determination of anionic surfactants. The optimized method was more sensitive than previously developed methods with LOD values of 2.35, 35.4, 37.0, 1.68, and 0.675 pg for SDS, SA, DBS, PFOS, and PFOA, respectively. The developed method was effectively applied for the determination of anionic surfactants in different water samples such as bottled drinking water, cooking water, tap water, and wastewater.

Topics: Alkanesulfonic Acids; Benzenesulfonates; Caprylates; Drinking Water; Fluorocarbons; Sodium Dodecyl Sulfate; Spectrometry, Mass, Electrospray Ionization; Stearic Acids; Surface-Active Agents; Tandem Mass Spectrometry; Wastewater; Water Pollutants, Chemical

The usefulness of the micellar selectivity triangle (MST) for prediction and interpretation of separation patterns in micellar electrokinetic chromatography (MEKC) separations is presented. In addition, we demonstrate the capability of controlling selectivity properties of micelles through addition of organic modifiers with known solvation properties as predicted by MST. The examples are modification of the hydrogen bond donor (HBD) micelle of lithium perfluorooctanesulfonate, the hydrogen bond acceptor (HBA) micelle of tetradecyltrimethylammonium bromide, and the sodium dodecyl sulfate micelles with intermediate hydrogen bonding properties with two hydrophobic organic modifiers. One is an aliphatic alcohol, n-pentanol that can act as both a HBA and a HBD; by contrast, the other organic modifier is a fluorinated alcohol, hexafluoroisopropanol that is a strong HBD modifier and would enhance the hydrogen bond donor strength of micelles. A test sample composed of 20 small organic solutes representing HBA, HBD, and non-hydrogen bond aromatic compounds was carefully selected. The trends in retention behavior of these compounds in different micelles are consistent with the selectivity patterns predicted by the MST scheme. To the best of our knowledge, this is the first report on the unique selectivity of fluorinated alcohols as modifiers in MEKC. These results demonstrate the usefulness of the MST scheme for identifying pseudo-phases with highly similar or different selectivities and can serve as a guide for judicious selection of modifiers to create pseudo-phases with desired selectivity behavior on a rational basis.

Topics: Alcohols; Alkanesulfonic Acids; Chromatography, Micellar Electrokinetic Capillary; Fluorocarbons; Hydrogen Bonding; Hydrogen-Ion Concentration; Hydrophobic and Hydrophilic Interactions; Lithium; Micelles; Models, Chemical; Sodium Dodecyl Sulfate; Solvents; Trimethyl Ammonium Compounds

Lipophilicity and methylene selectivity of mixed pseudo-stationary phases (PSPs) (containing lithium dodecyl sulphate (LDS) and lithium perfluorooctanesulphonate (LiPFOS) in different molar ratios) applied in MEKC have been investigated. Micellar proportion (t(prop,mic), a quantity expressing that how much time is spent by the analyte in the micellar phase related to its whole migration time), CLOGP(50) value (showing the value of hydrophobicity of a molecule spending exactly 50% of its migration time in the PSP) and methylene selectivity have been determined for different LDS/LiPFOS mixed phases. Values of the above-mentioned parameters have been determined for analytes with different chemical structures (alkylbenzene and alkylphenone homologous series, alcohols). Good linear correlation was obtained between either the micellar proportion, CLOGP(50), or methylene selectivity and the phase composition for the mixed phases. Lipophilicity and methylene selectivity of the mixed LDS/LiPFOS PSPs can be calculated and can continuously be changed by mixing the two single phases (LDS and LiPFOS) in the appropriate (and calculable) portion.

Topics: Alkanesulfonic Acids; Chromatography, Micellar Electrokinetic Capillary; Fluorocarbons; Hydrocarbons; Hydrophobic and Hydrophilic Interactions; Linear Models; Lithium Compounds; Micelles; Models, Chemical; Sensitivity and Specificity; Sodium Dodecyl Sulfate

In this study, octadecyl (C(18)) and aminopropyl group modified titanate nanotubes (C(18)/NH(2)-TNs) were prepared successfully with a silylation method by introducing octadecyltrimethoxysilane (ODS) and aminopropyltrimethoxysilane (APS) simultaneously to the surface of titanate nanotubes (TNs). The properties of the products were characterized in detail. The results indicated that there might be steric hindrance effects to C(18) groups on the nanoscaled interior and exterior space of TNs. Therefore, aminopropyl groups were more ready to immobilize on the surface of TNs than C(18) groups when the organosilanes ODS and APS coexisted in reaction solution. C(18)/NH(2)-TNs with the obvious characteristic of C(18) and aminopropyl groups were obtained as the ratio of ODS/APS in reaction solution was 4.0, and the corresponding proportion of the two groups (C(18)/NH(2)) on the C(18)/NH(2)-TN surface was about 0.25. This adsorbent had good water dispersibility, overcoming the bad deficiency of reverse phase nanosized materials in water and improving its accessibility to polar analytes. Due to the cooperative effect of alkyl and aminopropyl groups coupled with the residual hydroxyl groups on the surface, C(18)/NH(2)-TNs exhibited excellent affinity efficiency to some ionic or ionizable organic analytes under a different solution pH, including anionic (perfluorooctane sulfonate, perfluorooctanoic acid, and sodium dodecyl sulfate), cationic (cetyltrimethylammonium bromide), and amphoteric compounds (sulfamethazine). The selective binding of these anionic, amphoteric, and cationic analytes could be achieved by adjusting solution pH to acid, neutral, and alkaline conditions, respectively. Since C(18)/NH(2)-TNs possessed relatively large surface areas and strong affinity ability to ionic analytes, especially with long alkyl chains, it showed significantly higher adsorption capacity for perfluorooctane sulfonate than activated carbon and anion-exchange resin.

Topics: Adsorption; Alkanesulfonic Acids; Caprylates; Cetrimonium; Cetrimonium Compounds; Fluorocarbons; Hydrogen-Ion Concentration; Nanotubes; Organosilicon Compounds; Particle Size; Propylamines; Silanes; Sodium Dodecyl Sulfate; Sulfamethazine; Surface Properties; Titanium

A marked acceleration property for the Diels-Alder reaction was observed in an aqueous micellar system composed of perfluorohexane and lithium perfluorooctanesulfonate. The reaction rate increased with the concentration of the equimolar mixture of PFH and LiFOS, and the rate in 500 mM PFH and 500 mM LiFOS was about 100-fold greater than that in water without the fluorous field. After completion of the reaction, the products were simply extracted from the aqueous reaction mixture using n-hexane. [reaction: see text].

Topics: Alkanesulfonic Acids; Emulsions; Fluorocarbons; Hexanes; Kinetics; Lithium; Sodium Dodecyl Sulfate; Solvents; Water

Surfactants suppress the electrospray ionization (ESI) of various compounds. Here we demonstrate that fluorinated surfactants such as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOSA) could be employed for ESI-MS without a significant decrease in sensitivity. Both PFOA and PFOSA could be applied to the analysis of ionic and nonionic compounds by micellar electrokinetic chromatography (MEKC)/ESI-MS, although the migration window was limited. Furthermore, in HPLC/ESI-MS, PFOA could function as a paired ion for enzymatically digested peptides as well as sulfonamides and significant effects of PFOA on the signal peak shape, retention times, and sensitivity of the analytes were observed compared to those of trifluoroacetic acid or sodium dodecyl sulfate (SDS). In addition, PFOA was applied to protein analysis by ESI-MS, and superior sensitivity was noted, compared to other surfactants such as octylglucoside, dodecylglucoside, and SDS. Although 21% of the original signal was observed in the presence of 1% PFOA, this surfactant could be easily removed by evaporation, which resulted in the recovery of 96% of the original signal. Because these fluorinated surfactants could also be used for solubilization, extraction, and disaggregation of proteins, they should greatly expand the applicability of the ESI-MS to the biological problems of proteins.

Topics: Adrenergic beta-Antagonists; Alkanesulfonic Acids; Caffeine; Caprylates; Chromatography, High Pressure Liquid; Detergents; Fluorocarbons; Micelles; Myoglobin; Peptides; Protein Conformation; Sensitivity and Specificity; Sodium Dodecyl Sulfate; Spectrometry, Mass, Electrospray Ionization; Surface-Active Agents; Trifluoroacetic Acid