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Anionic Surfactants (anionic + surfactant)

Distribution by Scientific Domains

Chemistry	56%
Life Sciences	13%
Polymers and Materials Science	10%

Distribution within Chemistry

Analytical Chemistry	17%

Selected Abstracts

Innentitelbild: Thin-Film Formation of Imidazolium-Based Conjugated Polydiacetylenes and Their Application for Sensing Anionic Surfactants (Angew. Chem.

ANGEWANDTE CHEMIE, Issue 8 2010
8/2010)
Der induzierte Blau-Rot-Übergang in Polydiacetylenen (PDAs) bildet die Grundlage für verschiedene PDA-Chemosensoren. In ihrer Zuschrift auf S.,1464,ff. beschreiben J. Yoon, J.,Y. Lee und Mitarbeiter einen tensidselektiven Sensor bestehend aus Imidazolium-PDA, der mit selektiver Verfärbung auf anionische Tenside reagiert und beispielsweise zwischen den anionischen Tensiden Natriumdodecylsulfat (SDS) und Natriumdodecylbenzolsulfonat (SDBS) unterscheiden kann. [source]

Thin-Film Formation of Imidazolium-Based Conjugated Polydiacetylenes and Their Application for Sensing Anionic Surfactants,

ANGEWANDTE CHEMIE, Issue 8 2010
Xiaoqiang Chen
Farbe bekennen: Polydiacetylen-Imidazolium-Polymere reagieren durch selektive Farbwechsel auf den Zusatz anionischer Tenside. Das System unterscheidet zudem zwischen den anionischen Tensiden Natriumdodecylsulfat (SDS) und Natriumdodecylbenzolsulfonat (SDBS). [source]

Low-Temperature Synthesis of Star-Shaped PbS Nanocrystals in Aqueous Solutions of Mixed Cationic/Anionic Surfactants,

ADVANCED MATERIALS, Issue 3 2006
N. Zhao
Uniform, well-defined star-shaped PbS nanocrystals with tunable sizes (40,100,nm, see Figure), as well as octahedral PbS nanocrystals, have been readily synthesized in aqueous solutions containing a mixture of the surfactants cetyltrimethylammonium bromide/ sodium dodecyl sulfate (CTAB/SDS) at low temperature (80,°C). The size of the PbS nanostars can be accurately controlled by adjusting the reaction time. This result may open new avenues for the green chemical synthesis of shape-controlled semiconductor nanocrystals. [source]

Sensitive, label-free protein assay using 1-ethyl-3-methylimidazolium tetrafluoroborate-supported microchip electrophoresis with laser-induced fluorescence detection

ELECTROPHORESIS, Issue 9 2008
Yuanhong Xu
Abstract Based on the dimer,monomer equilibrium movement of the fluorescent dye Pyronin Y (PY), a rapid, simple, highly sensitive, label-free method for protein detection was developed by microchip electrophoresis with LIF detection. PY formed a nonfluorescent dimer induced by the premicellar aggregation of an anionic surfactant, SDS, however, the fluorescence intensity of the system increased dramatically when proteins such as BSA, bovine hemoglobin, cytochrome c, and trypsin were added to the solution due to the transition of dimer to fluorescent monomer. Furthermore, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) instead of PBS was applied as running buffers in microchip electrophoresis. Due to the excellent properties of EMImBF4, not only nonspecific protein adsorption was more efficiently suppressed, but also approximately ten-fold higher fluorescence intensity enhancement was obtained than that using PBS. Under the optimal conditions, detection limits for BSA, bovine hemoglobin, cytochrome c, and trypsin were 1.00×10,6, 2×10,6, 7×10,7, and 5×10,7 mg/mL, respectively. Thus, without covalent modification of the protein, a protein assay method with high sensitivity was achieved on microchips. [source]

Microchip-based small, dense low-density lipoproteins assay for coronary heart disease risk assessment

ELECTROPHORESIS, Issue 9 2008
Hua Wang
Abstract Small, dense low-density lipoprotein (sdLDL) has been accepted as an emerging cardiovascular risk factor, and there has been an increasing interest in analytical methods for sdLDL profiling for diagnosis. Serum sdLDL may be measured by different laboratory techniques, but all these methods are laborious, time-consuming, and costly. Recently, we have demonstrated that a low-temperature bonding of quartz microfluidic chips for serum lipoproteins analysis (Zhuang, G., Jin, Q., Liu, J., Cong, H. et al., Biomed. Microdevices 2006, 8, 255,261). In contrast to this previous study, we chose SDS as anionic surfactant to modify both lipoproteins and the channel surface to minimize lipoprotein adsorption and improve the resolution of lipoprotein separation. Two major LDL subclass patterns including large, buoyant LDL (lLDL), sdLDL, and high-density lipoprotein (HDL) were effectively separated with high reproducibility. RSD values of the migration time (min) and peak areas of standard LDL and HDL were 6.28, 4.02, 5.02, and 2.5%, respectively. Serum lipoproteins of 15 healthy subjects and 15 patients with coronary heart disease (CHD) were separated by microchip CE. No peaks of sdLDL were detected in serum samples of healthy subjects while sdLDL fractional peaks were observed in patients' entire serum samples. These results suggested that the microchip-based sdLDLs assay was a simple, rapid, and highly efficient technique and significantly improved the analysis of CHD risk factors. [source]

Kinetic investigation on the oxidation of nitrite by oxochromium(V) ion in aqueous and micellar systems

INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 2 2004
Mookandi Kanthimathi
The kinetics of oxidation of nitrite by [O = CrV (5-chlorosalen)]+ complex has been studied spectrophotometrically at [CrV] = 0.5 × 10,3 M, [NO2,] = 0.01,0.1 M, [H+] = 0.0001,0.05 M, I = 0.15 M, and T = 25°C in the presence of cationic surfactant, cetyl pyridium chloride (CPC), and anionic surfactant, sodium dodecyl sulfate (SDS),in aqueous acidic medium. The oxygen atom transfer reaction from O = CrV to nitrite ion is influenced by the ionic nature of the micelle. The redox reaction is accelerated in presence of CPC and slowed down by 40 times in presence of SDS. The mechanism of the reaction involves an inner-sphere process involving the formation of an intermediate followed by oxo transfer process. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 36: 79,86 2004 [source]

Spectral, kinetic, and redox properties of basic fuchsin in homogeneous aqueous and sodium dodecyl sulfate micellar media

INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 12 2003
N. Ramanathan
Effect of anionic surfactant on the optical absorption spectra and redox reaction of basic fuchsin, a cationic dye, has been studied. Increase in the absorbance of the dye band at 546 nm with sodium dodecyl sulfate (SDS) is assigned to the incorporation of the dye in the surfactant micelles with critical micellar concentration (CMC) of 7.3 × 10,3 mol dm,3. At low surfactant concentration (<5 × 10,3 mol dm,3) decrease in the absorbance of the dye band at 546 nm is attributed to the formation of a dye,surfactant complex (1:1). The environment, in terms of dielectric constant, experienced by basic fuchsin inside the surfactant micelles has been estimated. The association constant (KA) for the formation of dye,SDS complex and the binding constant (KB) for the micellization of dye are determined. Stopped-flow studies, in the premicellar region, indicated simultaneous depletion of dye absorption and formation of new band at 490 nm with a distinct isosbestic point at 520 nm and the rate constant for this region increased with increasing SDS concentration. The reaction of hydrated electron with the dye and the decay of the semireduced dye are observed to be slowed down in the presence of SDS. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 629,636, 2003 [source]

Targeted delivery of salicylic acid from acne treatment products into and through skin: role of solution and ingredient properties and relationships to irritation

INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 4 2004
L. Rhein
Salicylic acid (SA) is a beta-hydroxy acid and has multifunctional uses in the treatment of various diseases in skin such as acne, psoriasis, and photoaging. One problem often cited as associated with salicylic acid is that it can be quite irritating at pH 3,4, where it exhibits the highest activity in the treatment of skin diseases. We have identified strategies to control the irritation potential of salicylic acid formulations and have focused on hydroalcoholic solutions used in acne wipes. One strategy is to control the penetration of SA into the skin. Penetration of the drug into various layers of skin, i.e. epidermis, dermis, and receptor fluid, was measured using a modified Franz in vitro diffusion method after various exposure times up to 24 h. A polyurethane polymer (polyolprepolymer-15) was found to be an effective agent in controlling delivery of SA. In a dose-dependent fashion it targeted delivery of more SA to the epidermis as compared to penetration through the skin into the receptor fluid. It also reduced the rapid rate of permeation of a large dose of SA through the skin in the first few hours of exposure. A second strategy that proved successful was incorporation of known mild nonionic surfactants like isoceteth-20. These surfactants cleanse the skin, yet due to their inherent mildness (because of their reduced critical micelle concentration and monomer concentration), keep the barrier intact. Also, they reduce the rate of salicylic acid penetration, presumably through micellar entrapment (either in solution or on the skin surface after the alcohol evaporates). Cumulative irritation studies showed that targeting delivery of SA to the epidermis and reducing the rapid early rate of penetration of large amounts of drug through the skin resulted in a reduced irritation potential. In vivo irritation studies also showed that the surfactant system is the most important factor controlling irritancy. SA delivery is secondary, as formulations with less SA content reduced the rate of delivery to the receptor and yet were some of the most irritating formulations tested, presumably due to the action of the specific anionic surfactant on the barrier. Alcohol content also did not appreciably affect irritation and SA delivery; formulations with considerably low alcohol content but containing anionic versus nonionic surfactant systems exhibited considerably higher irritancy. Thus the surfactant type was again the predominant factor in those studies, although arguably alcohol plays some role (solubilization of SA). Results showed that both polymers and mild surfactants work in concert to provide the optimal formulation benefits of targeted delivery and reduced irritation. Synergistic relationships among hydroalcoholic formulation components will be discussed along with the mechanisms likely involved in controlling delivery of SA to skin. [source]

Conditioning polymers in today's shampoo formulations , efficacy, mechanism and test methods

INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2000
Hössel
Synopsis Today's shampoo formulations are beyond the stage of pure cleansing of the hair. Additional benefits are expected, e.g. conditioning, smoothing of the hair surface, improvement of combability and lather creaminess. Cationic polymers play an important role in providing many of those features. Therefore, within the last few years their use in shampoos has increased greatly. In the only last two decades, shampoo designation has gradually changed from ,2-in-1' to ,3-in-1' and then to ,multifunctional', as at present. The consumer demands products which live up to their promises. Modern shampoos contain a wide variety of ingredients such as co-surfactants, vitamins and pro-vitamins, protein derivatives, silicones, natural-based plant extracts and other ,active ingredients', but there is still a need for conditioning polymers. The specific objective of this study is to assess the conditioning efficacy of cationic polymers and to investigate their mechanisms in a shampoo system. The investigations were carried out on formulations that contained sodium lauryl ether sulphate and different cationic polymers, e.g. Polyquaternium 7, 10, 11, cationic guar gum and Luviquat Care (Polyquaternium 44), a new branched copolymer of vinylpyrrolidone (VP) and quaternized vinylimidazolium salts (QVI). We used test methods relevant to the applications in question, such as combing force measurements, the feel of the hair and the creaminess of the lather, to assess the efficacy. Atomic force microscopy and electrokinetics (streaming potential) were used to detect polymer residues on treated hair. All the polymers under investigation improved the overall performance of the shampoo formulations. This was demonstrated by means of combing force measurements, sensorial tests and analytical methods, namely zeta potential measurement and atomic force microscopy. Polyquaternium 44 exhibited the best conditioning properties on wet hair without sacrificing removability or absence of build-up. The latter are the most striking weaknesses of cationic Guar Gum-based polymers. Polyquaternium 10 can also be removed from the hair after rinsing with anionic surfactant but it does not perform as well as Polyquaternium 44 in the fields of wet combability and sensorial criteria such as lather creaminess and feel of the hair. We postulate that the outstanding properties of Polyquaternium 44 as a conditioning agent for shampoos are due to its tailor-made ,branched' structure. There is a clear correlation between the molecular weight and the efficacy of the new copolymers of VP and QVI. Only cationic polymers with a very high molecular weight are effective as conditioners in shampoos based on anionic surfactants. Surprisingly, they do not have to have a high cationic charge. On the basis of all our results, our postulation is that the polymer residue which is responsible for conditioning does not form a flat layer on the hair. Rather, the polymer residue adsorbs with the few cationic moieties, while the uncharged part of the polymer forms loops, which are orientated away from the hair and which are responsible for the reduced friction between hairs. Résumé Les formulations actuelles de shampoing font plus qu'un simple nettoyage des cheveux. On en attend un intérêt supplémentaire, par exemple après-shampoing, lissage de la surface du cheveu, amélioration de la coiffabilité et aspect crémeux du savon. Les polymères cationiques jouent un rôle important dans l'apport de nombre de ces caractéristiques. Par conséquent, ces quelques dernières années leur utilisation a considérablement augmenté dans les shampoings. Dans les seules deux dernières décades, l'appellation du shampoing est progressivement passée de "2 en 1"à"3 en 1" puis ensuite à"multifonctionnel", comme actuellement. Le consommateur recherche des produits qui tiennent leurs promesses. Les shampoings modernes contiennent une grande diversité d'ingrédients tels que des co-tensioactifs, des vitamines et des provitamines, des dérivés de protéines, des silicones, des extraits à base de plantes naturelles et autres "ingrédients actifs", mais il existe toujours un besoin pour des polymères d'après shampoing. L'objectif spécifique de cette étude est d'évaluer l'efficacité comme après-shampoing de polymères cationiques et de rechercher leurs mécanismes dans le système de shampoing. Les recherches ont été menées sur des formulations qui contiennent du sulfate de lauryl éther sodium et différents polymères cationiques, par exemple du Polyquaternium 7, 10, 11, de la gomme de guar cationique et du Luviquat Care (Polyquaternium 44), un nouveau copolymère ramifié de vinylpyrrolidone (VP) et de sels quaternaires de vinylimidazolium (QVI). Nous avons utilisé les procédés de contrôle appropriées aux applications en question, tels que les mesures de force de coiffage, le toucher du cheveu et l'aspect crémeux du savon, pour évaluer l'efficacité. La microscopie atomique et l'électrocinétique (potentiel d'écoulement) ont été utilisées pour détecter les résidus de polymère sur le cheveu traité. Tous les polymères étudiés améliorent le comportement global des formulations de shampoing. Ceci est démontré au moyen des mesures de force de coiffage, des tests sensoriels et des méthodes analytiques, en l'occurrence la mesure du potentiel zêta et la microscopie atomique. Le Polyquaternium 44 présente les meilleures propriétés d'après-shampoing sur cheveu mouillé sans diminuer sa capacité d'élimination ou l'absence d'accumulation. Ces dernières sont les faiblesses les plus frappantes des polymères à base de gomme de guar cationique. Le Polyquaternium 10 peut aussi être éliminé du cheveu après rinçage avec un tensioactif anionique mais il ne se comporte pas aussi bien que le Polyquaternium 44 dans les domaines de la coiffabilitéà l'état mouillé et des critères sensoriels tels que l'aspect crémeux du savon et du toucher du cheveu. Nous supposons que les propriétés exceptionnelles du Polyquaternium 44 comme agent après-shampoing pour shampoings sont dues à sa structure "ramifiée" conçue sur mesure. Il existe une corrélation claire entre le poids moléculaire et l'efficacité des nouveaux copolymères de VP et QVI. Seuls les polymères cationiques avec un poids moléculaire très élevé sont efficaces comme après shampoings dans des shampoings à base de tensioactifs anioniques. Etonnamment, ils n'ont pas besoin d'avoir une charge cationique élevée. Sur la base de tous nos résultats, notre hypothèse est que le fragment de polymère qui est responsable du traitement ne forme pas une couche plate sur le cheveu. Le fragment de polymère adsorbe plutôt les quelques fragments cationiques, tandis que la partie non chargée du polymère forme des boucles, qui sont orientées à l'extérieur du cheveu et qui sont responsables de la friction réduite entre les cheveux. [source]

Effect of surfactants and liquid hydrocarbons on gas hydrate formation rate and storage capacity

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 8 2003
Zhigao Sun
Abstract Hydrate formation rate plays an important role in making hydrates for the storage and transport of natural gas. Micellar surfactant solutions were found to increase gas hydrate formation rate and storage capacity. With the presence of surfactant, hydrate could form quickly in a quiescent system and the energy costs of hydrate formation reduced. Surfactants (an anionic surfactant, a non-ionic surfactant and their mixtures) and liquid hydrocarbons (cyclopentane and methylcyclohexane) were used to improve hydrate formation. The experiments of hydrate formation were carried out in the pressure range 3.69,6.82 MPa and the temperature range 274.05,277.55 K. The experimental pressures were kept constant during hydrate formation in each experimental run. The effect of anionic surfactant (sodium dodecyl sulphate (SDS)) on natural gas storage in hydrates is more pronounced compared to a non-ionic surfactant (dodecyl polysaccharide glycoside (DPG)). The induction time of hydrate formation was reduced with the presence of cyclopentane (CP). Cyclopentane and methylcyclohexane (MCH) could increase hydrate formation rate, but reduced hydrate storage capacity The higher methylcyclohexane concentration, the lower the hydrate storage capacity. Copyright © 2003 John Wiley & Sons, Ltd. [source]

The role of surfactants in the reversal of active transport mediated by multidrug resistance proteins

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2003
Katrijn Bogman
Abstract A variety of seven nonionic, one amphoteric and, one anionic surfactant that are applied or investigated as surfactants in drug formulation, were analyzed for their capacity to modulate carrier-mediated transport by efflux pumps. Two cell lines, murine monocytic leukemia cells overexpressing P-glycoprotein (P-gp) and Madin-Darby canine kidney cells stably overexpresssing human multidrug resistance-associated protein 2 (MRP2), were used as test systems. The modulation of P-gp and of MRP2 function was studied by the reversal of rhodamine 123 and of methylfluorescein-glutathione conjugate transport, respectively. Mechanisms that were not transporter related and could lead to misinterpretations were identified, such as probe quenching, probe encapsulation by micelles, and membrane damage. P-gp-mediated rhodamine 123 transport was inhibited by five nonionic surfactants in a concentration-dependent manner and in the order TPGS,>,Pluronic PE8100,>,Cremophor EL,>,Pluronic PE6100,,,Tween 80. In contrast, none of the surfactants showed a significant inhibition of MRP2-mediated efflux in Madin-Darby canine kidney/MRP2 cells. In conclusion, the results indicate that surfactants demonstrate a transporter-specific interaction, rather than unspecific membrane permeabilization. The present analysis offers insight in the possible mechanisms of surfactant interactions with biological membranes and could help to identify specific drug formulations. © 2003 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 92:1250,1261, 2003 [source]

The production of high polymer to surfactant microlatexes

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2010
Raul P. Moraes
Abstract Starved-feed microemulsion polymerization of styrene was investigated. The influence of the type (SDS or Dowfax 2A1) and concentration of anionic surfactant on the final particle size of latex made by the polymerization of microemulsions of styrene was studied. In addition, the influence of 1-pentanol and acrylic acid as cosurfactants was examined. Latexes with 20% solids content and polymer to surfactant ratio of 22 were produced, with a particle diameter of 42 nm and very low polydispersity indexes. Smaller particles are produced using SDS than Dowfax 2A1 for the same weight fraction of surfactant; however, similar particle sizes were obtained with the same molar concentrations of SDS and Dowfax 2A1. Further shot additions of monomer increased solids level as high as 40% and polymer to surfactant ratios greater than 40, with particles remaining monodisperse with average diameter smaller than 60 nm. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 48,54, 2010 [source]

Simultaneous determination of digoxin and digitoxin by micellar electrokinetic chromatography and application to drug formulations

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 18 2003
Hsiu-Hui Tseng
Abstract A simple micellar electrokinetic chromatographic method is described for simultaneous determination of digoxin and digitoxin. The simultaneous analysis of digoxin and digitoxin was performed in Tris buffer (10 mM; pH 9) with 90 mM sodium dodecyl sulfate and 10% isopropyl alcohol as an anionic surfactant and organic modifier. Under these conditions, good separation with high efficiency is achieved in short analysis times. Several parameters affecting the separation of the drugs were studied, including the pH and concentrations of the Tris buffer and sodium dodecyl sulfate. The linear range of the method for the determination of digoxin and digitoxin was over 0.01,0.3 mg/mL; the detection limit (signal to noise ratio = 3; injection 3.5 kPa 3 s) was 4 and 6 ,g/mL, respectively. Application of the proposed method to the determination of digoxin in commercial tablets and in injections proved to be feasible. [source]

Resonance Rayleigh scattering method for the determination of chitosan with some anionic surfactants

LUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 3 2008
Yu-Wei Wang
Abstract In weak acidic buffer medium, chitosan binding with an anionic surfactant, such as sodium dodecyl benzene sulphonate (SDBS), sodium lauryl sulphate (SLS) or sodium dodecyl sulphonate (SDS), can result in a significant enhancement of resonance Rayleigh scattering (RRS) intensity. The results showed that under optimum conditions the enhanced RRS intensity is proportional to the concentration of chitosan in the range 0.10,20.0 µg/mL for SDBS, 0.27,15.0 µg/mL for SLS and 0.20,15.0 µg/mL for SDS. Among these, the sensitivity of SDBS is the highest and its detection limit for chitosan is 29 ng/mL, while those of SLS and SDS are 83 and 61 ng/mL, respectively. The method has good selectivity and was applied to the determination of trace amounts of chitosan in practical samples with satisfactory results. Therefore, a simple and convenient method with high sensitivity and selectivity for the determination of chitosan was established. Copyright © 2008 John Wiley & Sons, Ltd. [source]

The effect of sodium dodecyl sulfate and anion-exchange silica gel on matrix-assisted laser desorption/ionization mass spectrometric analysis of proteins

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 11 2009
Miwako Asanuma
Sodium dodecyl sulfate (SDS), an anionic surfactant, is widely used in peptide and protein sample preparation. When the sample is analyzed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), this surfactant can often cause signal suppression. We have previously reported an on-probe sample preparation method using a suspension of anion-exchange silica gel and sinapinic acid (i.e., gel-SA suspension) as a matrix, thereby greatly improving the MALDI signal detection of the protein solutions containing SDS. In this study, we found that a certain amount of SDS enhanced the MALDI signal intensity for protein samples. This effect was also observed when using sodium decyl sulfate and sodium tetradecyl sulfate instead of SDS. Furthermore, this on-probe sample preparation method using both SDS and the gel-SA suspension improved the detection limit of protein samples in the MALDI-MS analysis by about ten-fold as compared to that of protein samples without SDS and the gel-SA suspension. This method can be applied not only to the MALDI-MS analysis of samples containing SDS, but also to the examination of proteins at femtomole levels or insoluble proteins such as membrane proteins. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Solubilisation of dyes by surfactant micelles.

COLORATION TECHNOLOGY, Issue 6 2004
Part 5: Durability of dye fixatives
A number of direct and indirect techniques have been used to explore the durability of dye fixatives on laundering with anionic detergent formulations. The most useful technique for quantifying fixative loss was found to be UV spectroscopy but this is not applicable in every case. Overall, it was found that the fixatives examined were durable to six washes in a typical colour-care detergent formulation at 40 °C. It is concluded that a major contribution to dye loss from fixed cloth at low temperature is the displacement by anionic surfactant of dye bound to the fixative. In addition to being more substantive, good quality fixatives may compete more effectively for dye and may physically entrap the dye within the fibre. [source]

Electrochemical Behavior of Catecholamines and Related Compounds at In Situ Surfactant Modified Carbon Paste Electrodes

ELECTROANALYSIS, Issue 2-3 2007
M.Carmen Blanco-López
Abstract The voltammetric characteristics of catecholamines: epinephrine (E) and norepinephrine (NE) and related compounds: isoproterenol, metanephrine, L -dopa, methyldopa, vanillylmandelic acid (VMA), and homovanillic acid (HVA) at unmodified and in situ surfactant- modified carbon paste electrodes were comparatively evaluated. For the basic and amphoteric compounds the modification of the electrode surface with submicellar concentrations of anionic surfactants (sodium dodecylsulfate, sodium decylsulfate or sodium dodecylsulfonate) produce an important current enhancement in its oxidation and reduction peak current together with the improvement in the reversibility of the processes. These effects were explained in basis on electrostatic and hydrophobic interactions. On the other hand, the oxidation of acidic metabolites, HVA and VMA, was studied at electrodes modified in situ with cationic surfactants. Under certain conditions the surfactant could stabilise some of the electrochemical reaction intermediates, thus explaining the different voltammetric behaviour of HVA and VMA. [source]

Adsorption of hydrophobic organic compounds onto a hydrophobic carbonaceous geosorbent in the presence of surfactants,

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2008
Peng Wang
Abstract The adsorption of hydrophobic organic compounds (HOCs; atrazine and diuron) onto lampblack was studied in the presence of nonionic, cationic, and anionic surfactants (Triton® X-100), benzalkonium chloride [BC], and linear alkylbenzene sulfonate [LAS]) to determine the effect of the surfactant on HOC adsorption onto a hydrophobic carbonaceous geosorbent. Linear alkylbenzene sulfonate showed an adsorption capacity higher than that of BC but similar to that of Triton X-100, implying the charge property of a surfactant is not a useful indicator for predicting the surfactant's adsorption onto a hydrophobic medium. The results also indicated that the octanol-water partition coefficient (Kow) of a surfactant is not a good predictor of that surfactant's sorption onto a hydrophobic medium. Under subsaturation adsorption conditions (i.e., before sorption saturation is reached), surfactant adsorption reduced HOC adsorption to a significant extent, with the reduction in HOC adsorption increasing monotonically with the amount of surfactant adsorbed. Among the three surfactants, Triton X-100 was the most effective in reducing HOC adsorption, whereas BC and LAS showed similar effectiveness in this regard. Under the same amount of the surfactant sorbed, the reduction in atrazine adsorption was consistently greater than that for diuron because of atrazine's lower hydrophobicity. No significant difference was observed in the amount of the HOC adsorbed under different adsorption sequences. Our results showed that the presence of surfactant can significantly decrease HOC adsorption onto hydrophobic environmental media and, thus, is important in predicting HOC fate and transport in the environment. [source]

Efficient Removal of Anionic Surfactants Using Mesoporous Functionalised Hybrid Materials

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 25 2009
Carmen Coll
Abstract A new hybrid system for surfactant removal from water has been developed using mesoporous material (MCM-41) functionalised with suitable binding groups. Solid S1, S2 and S3 were prepared by reaction of the mesoporous material with N -methyl- N, -(propyltrimethoxysilyl)imidazolium chloride, (3-aminopropyl)trimethoxysilane or 4-[(triethoxysilylpropylthio)methyl]pyridine, respectively. The functionalised materials were characterised following standard solid-state techniques. The final prepared solids consist of a siliceous MCM-41-type mesoporous support with the surface decorated by imidazolium, amine and pyridine binding groups suitable for anion coordination. Equilibrium adsorption studies of linear alkylbenzenesulfonate (LAS) using S1, S2 and S3 in water have been carried out. The obtained adsorption data were correlated with a Langmuir isotherm model that gives an acceptable description of the experimental data. The maximum surfactant uptake/binding site (mol,mol,1) and the surfactant adsorption capacity (mmol,g,1) for materials S1, S2 and S3 were calculated. S1 shows a positive-charged functionalised surface that is independent of the pH of the solution, whereas S2 and S3 are functionalised with neutral groups that need to be protonated in order to display electrostatic binding interactions with the anionic surfactants. Therefore, whereas the adsorption capacity of S1 is pH-independent, S2 and S3 display larger LAS adsorption at acidic pH. The adsorption ability at a certain pH follows the order S1 >> S3 > S2. A remarkable maximum surfactant adsorption of 1.5 mmol per gram of material was observed for S1 at neutral pH. S2 and S3 behave as poorer adsorbents and show maximum surfactant adsorption of 0.197 and 0.335 mmol per gram of material, respectively, at pH 2.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

Time-of-flight secondary ion mass spectrometry analysis of the application of a cationic conditioner to ,clean' hair

INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 5 2004
A. Harvey
In this study the applicability of the surface-sensitive Time-of-flight secondary ion mass spectrometry (ToF-SIMS) technique to hair analysis and associated aqueous processing is evaluated. ToF-SIMS analysis of ,as received' human hair indicates the presence of silicones, anionic surfactants, and cationic conditioners, from previous treatments, on the fiber surface. Cleaning of the hair with SLS or SLES results in adsorption of the surfactants onto the fiber surface. In particular, the more non-polar surfactant components have greater substantivity for the fiber surface, as indicated by the relative increase in their ToF-SIMS intensity. Application of the Incroquat Behenyl 18-MEA conditioner to both ,virgin' and bleached hair results in the adsorption of the cationic C18, C20, C22, and C21 surfactant components onto the hair surface. The ToF-SIMS data indicate higher levels of conditioner on the bleached hair relative to the undamaged hair. [source]

Diffusion and distribution of element-labelled surfactants in human hair

INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 2 2004
F.-J. Wortmann
Synopsis To directly follow the diffusion process of cosmetically relevant agents into human hair, a specific methodological approach is presented and elucidated for selected surfactants. For this, practically relevant anionic and cationic surfactants were synthesized with a chlorine atom at the end of their alkyl chain. The property changes of the surfactants through the modification are corresponding to an extension of the alkyl chain by about two methylene groups, thus representing a moderate increase of hydrophobicity. After the application of a modified surfactant to hair, it can be localized and quantified through its chlorine atom in cross-sections by scanning electron microscopy combined with micro X-ray fluorescence analysis. The determination of the diffusion coefficient D is realized through the application of the Matano-equation to element intensity profiles. Values for D vary within the chosen range of pH and temperature between 10,14 and 10,16 m2 s,1. The diffusion coefficients for the anionic surfactants increase with decreasing pH and increasing temperature, The temperature dependence follows in all cases the Arrhenius relationship with activation energies EA of 50,100 kJ mol,1, which decrease with pH. The pH-related effects, with comparable values for D and EA, are opposite for the cationic surfactant. These observations are consistently interpreted on the basis of ionic and hydrophobic interactions in hair. Résumé Afin de suivre directement le processus de diffusion d'agents cosmétiques pertinents dans le cheveu humain, une approche méthodologique spécifique est présentée et approfondie pour des tensio actifs sélectionnés. En pratique, des tensio actifs pertinents, anioniques et cationiques ont été synthétisés en introduisant un atome de Chlore à l'extrémité de leur chaîne alkyle. Les changements de propriétés de ces tensio actifs, via cette modification, correspondent à un allongement de la chaîne alkyle d'environ deux groupes méthylène, représentant ainsi une augmentation modérée de leur caractère hydrophobe. Suite à l'application sur le cheveu d'un tensio actif modifié, il peut être localisé et quantifié par l'atome de Chlore dans des coupes transverses par microscopie électronique à balayage couplée à l'analyse par micro Fluorescence X. La détermination du coefficient de diffusion D est effectuée par l'application de l'équation de Matano aux profils de l'intensité de l'élément. Les valeurs de D varient, selon l'échelle de pH et de température, entre 10,14 et 10,16 m2 s,1. Les coefficients de diffusion pour les tensio actifs anioniques augmentent avec des pH décroissants et des températures croissantes. La dépendance vis à vis de la température suit, dans tous les cas, la relation d'Arrhenius avec des énergies d'activation EA de 50 à 100 kJ mol,1, qui décroît avec le pH. Les effets liés au pH, avec des valeurs comparables de D et EA, sont opposés pour le tensio actif cationique. Ces observations sont constamment interprétées par les interactions de types ioniques et hydrophobes dans le cheveu. [source]

Conditioning polymers in today's shampoo formulations , efficacy, mechanism and test methods

Sharpless Asymmetric Dihydroxylation of Olefins in WaterSurfactant Media with Recycling of the Catalytic System by Membrane Nanofiltration

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2008

Abstract This paper presents a new and more sustainable alternative approach for the Sharpless catalytic asymmetric dihydroxylation (AD) of olefins using a water/surfactant system as reaction media. The AD reaction was performed using several cationic and anionic surfactants allowing yields and enantiomeric excesses higher or comparable with the conventional systems (using organic mixtures). The use of this water/surfactant medium offers the additional advantage of performing the reactions without the need of a slow addition of olefins. Asymmetric dihydroxylation of 1-hexene in a 1.5,mM sodium cholate aqueous solution, using N -methylmorpholine N -oxide (NMO) as co-oxidant was selected as model system to evaluate the feasibility of recycling the Sharpless catalytic system by nanofiltration. The reaction media was processed by nanofiltration, the product was isolated in the permeate, whereas the catalytic system and surfactant were retained by the membrane and recycled through six successive reactions, improving the catalyst turn-over number. The experimental results were compared with the ones calculated on the basis of mass balances, membrane rejections to product and reaction yields. [source]

Study of the solubilization of gliclazide by aqueous micellar solutions

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 4 2003
Khouloud A. Alkhamis
Abstract It was of interest to increase the solubility of gliclazide in aqueous media. Therefore, solubilization of gliclazide in a variety of surfactants was investigated. Anionic and cationic surfactants exhibited dramatic solubilizing ability for gliclazide, whereas nonionic surfactants showed significantly lower solubilizing ability. It was found that gliclazide solubility increases with increasing the carbon chain length of cationic surfactants and decreases with increasing the carbon chain length of anionic surfactants. The solubilization data were analyzed on the basis of a pseudo-phase model with gliclazide exhibiting moderate partition coefficients into the micellar phase. The possible sites of solubilization of gliclazide in the micelle were examined by studying the effect of NaCl on solubilization and by comparing the absorption spectra of gliclazide in different solvents. The results obtained from these two experiments indicated that gliclazide is solubilized mainly in the inner core of the cationic surfactant micelles and in the outer regions of the anionic surfactant micelles. © 2003 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 92:839,846, 2003 [source]

Controlled, radical reversible addition,fragmentation chain-transfer polymerization in high-surfactant-concentration ionic miniemulsions

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2004
J. B. McLeary
Abstract Living free-radical polymerization of methacrylate and styrenic monomers with ionic surfactants was carried out with reversible addition,fragmentation chain transfer in miniemulsion with different surfactant types and concentrations. The previously reported problem of phase separation was found to be insignificant at higher surfactant concentrations, and control of the molar mass and polydispersity index was superior to that of published miniemulsion systems. Cationic and anionic surfactants were used to examine the validity of the argument that ionic surfactants interfere with transfer agents. Ionic surfactants were suitable for miniemulsion polymerization under certain conditions. The colloidal stability of the miniemulsions was consistent with the predictions of a specific model. The living character of the polymer that comprised the latex material was shown by its transformation into block copolymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 960,974, 2004 [source]

Resonance Rayleigh scattering method for the determination of chitosan with some anionic surfactants

Kinetics of the M-Intermediate in the Photocycle of Bacteriorhodopsin upon Chemical Modification with Surfactants

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2010
Li-Kang Chu
The spectroscopic and kinetic studies of the interaction between bacteriorhodopsin in the M-intermediate and several surfactants (cetyl trimethyl ammonium bromide, dodecyl trimethyl ammonium bromide, diethylene glycol mono- n -hexyl ether, ethylene glycol mono- n -hexyl ether, sodium 1-decanesulfonate and sodium 1-heptanesulfonate) have been investigated using steady-state UV,VIS spectrometry and time-resolved absorption techniques. The steady-state spectral results show that bR retains its trimeric state. Time-resolved observations indicate that the rate of deprotonation of the protonated Schiff base increases in the presence of the cationic surfactants, whereas insignificant changes are observed in the neutral or anionic surfactants. The rate of the reprotonation of the Schiff base in the transition M , N is accelerated in anionic and neutral surfactants, but is decelerated in the presence of the cationic surfactants. Surfactants with a longer hydrocarbon tail have a greater effect on the kinetics when compared with surfactants having shorter hydrocarbon tails. The opposite effect is observed when the hydrophilic head of the surfactants contains opposite charges. These distinct kinetics are discussed in terms of the difference in the modified surface hydrophilicity of the bR and the possible protein configurational changes upon surfactant treatments. [source]

Interaction between aqueous solutions of polymer and surfactant and its effect on physicochemical properties

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2008
Mohammad Yunus Khan
Abstract Interaction between water-soluble polymers and anionic surfactants has been studied by surface tension and conductivity measurements. Sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS) were used as surfactant while polyacrylamide (PAA), commercial grade partially hydrolyzed polyacrylamide (PHPA), and xanthan gum were used as water-soluble polymers for the present study. The behavior of surfactant,polymer interaction was found to be dependent on both surfactant and polymer concentrations. After the critical aggregation concentration (CAC), interaction between the water-soluble polymer and surfactants was started and above the polymer saturation point (PSP) polymer was saturated by surfactant with no further change of surface tension and conductivity of the solution. It has also been found that alkali (NaOH) and salts (Na2CO3, NaCl) have significant influence on the polymer,surfactant interaction. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

,-Sheet aggregation of kisspeptin-10 is stimulated by heparin but inhibited by amphiphiles

BIOPOLYMERS, Issue 8 2010
Søren B. Nielsen
Abstract The murine 10-residue neurohormone kisspeptin (YNWNSFGLRY) is an important regulator of reproductive behavior and gonadotrophin secretion. It is known to form a random coil in solution, but undergoes a structural change in the presence of membranes although the nature of this change is not fully determined. The peptide's conformational versatility raises the question whether it is also able to form ordered aggregates under physiological conditions, which might be relevant as a storage mechanism. Here we show that heparin induces kisspeptin to form ,-sheet rich amyloid aggregates both at neutral (pH 7.0) and slightly acidic (pH 5.2) conditions. Addition of heparin leads to aggregation after a certain lag phase, irrespective of the time of addition of heparin, indicating that heparin is needed to facilitate the formation of fibrillation nuclei. Aggregation is completely inhibited by submicellar concentrations of zwitterionic and anionic surfactants. Unlike previous reports, our NMR data do not indicate persistent structure in the presence of zwitterionic surfactant micelles. Thus kisspeptin can aggregate under physiologically relevant conditions provided heparin is present, but the process is highly sensitive to the presence of amphiphiles, highlighting the very dynamic nature of the peptide conformation and suggesting that kisspeptin aggregation is a biologically regulatable process. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 678,689, 2010. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source]

Perylene Nanoparticles Prepared by Reprecipitation Method

CHINESE JOURNAL OF CHEMISTRY, Issue 2 2002
Xue-Hai Ji
Abstract Perylene nanoparticles with different sizes were prepared by reprecipitation method. It is found that the nanoparticles show size-dependent optical property. Electron diffraction patterns indicate that all the nanoparticles of different sizes are in crystalline state. The rapid growth of the nanoparticles during the aging process could be slowed down effectively by the addition of cationic or anionic surfactants. [source]