Sodium dodecyl sulfate coated γ-alumina support modified by a new Schiff base for solid phase extraction and flame-AAS determination of lead and copper ions

A simple and fast approach for solid phase extraction is herein described, and used to determine trace amounts of Pb2+ and Cu2+ metal ions. The solid phase support is sodium dodecyl sulfate (SDS)-coated γ-alumina modified with bis(2-hydroxy acetophenone)-1,6-hexanediimine (BHAH) ligand. The adsorbed ions were stripped from the solid phase by 6 mL of 4 M nitric acid as eluent. The eluting solution was analyzed by flame atomic absorption spectrometry (FAAS). The sorption recovery of metal ions was investigated with regard to the effects of pH, amount of ligand, γ-alumina and surfactant and the amount and type of eluent. Complexation of BHAH with Pb2+ or Cu2+ ions was examined via spectrophotometry using the HypSpec program. The detection limit for Cu2+ was 7.9 µg L-1 with a relative standard deviation of 1.67%, while that for Pb2+ was 6.4 µg L-1 with a relative standard deviation of 1.64%. A preconcentration factor of 100 was achieved for these ions. The method was successfully applied to determine analyte concentrations in samples of liver, parsley, cabbage, and water.

Molecular dynamics simulation of interactions between a sodium dodecyl sulfate micelle and a poly(ethylene oxide) polymer

We have performed atomistic molecular dynamics simulations of an anionic sodium dodecyl sulfate (SDS) micelle and a nonionic poly(ethylene oxide) (PEO) polymer in aqueous solution. The micelle consisted of 60 surfactant molecules, and the polymer chain lengths varied from 20 to 40 monomers. The force field parameters for PEO were adjusted by using 1,2-dimethoxymethane (DME) as a model compound and matching its hydration enthalpy and conformational behavior to experiment. Excellent agreement with previous experimental and simulation work was obtained through these modifications. The simulated scaling behavior of the PEO radius of gyration was also in close agreement with experimental results. The SDS-PEO simulations show that the polymer resides on the micelle surface and at the hydrocarbon-water interface, leading to a selective reduction in the hydrophobic contribution to the solvent-accessible surface area of the micelle. The association is mainly driven by hydrophobic interactions between the polymer and surfactant tails, while the interaction between the polymer and sulfate headgroups on the micelle surface is weak. The 40-monomer chain is mostly wrapped around the micelle, and nearly 90% of the monomers are adsorbed at low PEO concentration. Simulations were also performed with multiple 20-monomer chains, and gradual addition of polymer indicates that about 120 monomers are required to saturate the micelle surface. The stoichiometry of the resulting complex is in close agreement with experimental results, and the commonly accepted "beaded necklace" structure of the SDS-PEO complex is recovered by our simulations.

Determination of interfacial co-ion concentration in ionic micelles by chemical trapping: Halide concentration at the interface of sodium dodecyl sulfate micelles

Products from the spontaneous reaction of a long-chain arenediazonium salt, 2,6-dimethyl-4-hexadecylbenzenediazonium tetrafluoroborate(16-ArN2BF4), in aqueous micellar solutions of sodium dodecyl sulfate (SDS)? are used to estimate the local concentration of chloride and bromide ions at the micellar surface. The arenediazonium ion, 16-ArN2+, which is totally bound to the SDS micelle, reacts by rate-determining loss of N-2 to give an aryl cation that traps available nucleophiles, i,e., H2O, Cl-, and Br-, to give stable phenol, 16-ArOH, and halobenzene products, 16-ArCl and 16-ArBr, respectively. Product yields, determined by HPLC, are related to local concentrations using calibration curves obtained from independent standards. The local concentrations determined by this method are consistent with co-ion concentrations calculated, using a cell model, by numerical integration of the Poisson-Boltzmann equation (PBE) taking into account salt-induced micellar growth. The salt dependence of the intel facial concentrations of Cl- and Br- are identical. indicating no specific interactions in the interfacial co-ion compartment. PBE calculations predict that, in micellar SDS, increasing the concentration of a particular halide salt (NaX) at constant concentration of another halide (NaY) should result in an increase in the local concentrations of both co-ions. Using this chemical-trapping method, this prediction was demonstrated experimentally.

Mixed micelles of the anionic surfactant sodium dodecyl sulfate and the nonionic pentaethylene glycol mono-n-dodecyl ether in solution

Dynamic light scattering, surface tension, and clouding temperature have been monitored to elucidate the solution properties of mixed micelles formed between the anionic surfactant sodium dodecyl sulfate (SDS) and the nonionic surfactant pentaethylene glycol mono-n-dodecyl ether (C12E5) over a wide range of surfactant concentration and temperature. Addition of 0.1 M NaCl shifts the relaxational modes to higher frequency and lowers the clouding temperature (T-c) of the nonionic surfactant solution by about 1 degrees C compared to the salt-free system. T-c for the mixed surfactant solutions is higher than that of the binary C12E5 solutions and depends sensitively on the concentration of the two surfactants but increases only slightly when the total surfactant concentration is increased at a given molar C12E5/SDS concentration ratio. With C12E5/SDS = 5.7, for example, T-c is 46.0 and 47.5 degrees C, respectively, at 5 and 70 mM of C12E5 the mixed solutions are homogeneous and stable and contain nonspherical micelles, which are close to monodisperse over a range of surfactant concentrations and temperature. The mixed system has a lower Krafft point than binary SDS solutions and shows an approximately ideal behavior in contrast to the binary C12E5 solution. The hydrodynamic radius (RH) of the mixed micelle increases with temperature as do C12E5 micelles in the binary solutions and also with increasing C12E5/SDS ratio. At 25 degrees C, the critical micelle concentration of the mixed solution lies between those of the individual surfactants and decreases as the C12E5/SDS ratio is increased.

pH at the micellar interface: Synthesis of pH probes derived from salicylic acid, acid-base dissociation in sodium dodecyl sulfate micelles, and Poisson-Boltzmann simulation

The study of the H+ concentration at the micellar interface is a convenient system for modeling the distribution of H+ at interfaces. We have synthesized salicylic acid derivatives to analyze the proton dissociation of both the carboxylic and phenol groups of' the probes, determining spectrophotometrically the apparent pK(a)'s (pK(ap)) in sodium dodecyl Sulfate, SDS, micelles with and without added salt. The synthesized probes were 2-hydroxy-5-(2-trimethylammoniumacetyl)benzoate; 2-hydroxy-5-(2-dimethylhexadecylammoniumacetyl)benzoate- 2-hydroxy-5-(2-dimethylhexadecylammoniumhexanoyl)benzoate-, 2-hydroxy-5-(2-diniethylhexadecylammoniumundecanoyl)betizoate; 2-hydroxy-5-acetylbenzoic acids and 2-hydroxy-5-dodecanoylbenzoic acid. Upon incorporation into SDS micelles the pK(ap)'s of both carboxylic and phenol groups increased by ca. 3 pH units and NaCl addition caused a decrease in the probe-incorporated pKap. The experimental results were fitted with a cell model Poisson-Boltzmann (P-B) equation taking in consideration the effect of salt on the aggregation number of SDS and using the distance of' the dissociating group as a parameter. The conformations of the probes were analyzed theoretically using two dielectric constants, e.g., 2 and 78. Both the P-B analysis and conformation calculations can be interpreted by assuming that the acid groups dissociate very close to, or at, the interface. Our results are consistent with the assumption that the intrinsic pK(a)'s of both carboxylic and phenol groups of the salicylic acid probes used here can be taken as those in water. Using this assumption the micellar and salt effects on the pKap's of the (trialkylammonium)benzoate probes were described accurately using a cell model P-B analysis. (c) 2005 Elsevier B.V. All rights reserved.

Electrochemical behavior of cobalt oxide coatings on cold-rolled steel in alkaline sodium sulfate

The electrochemical behavior of a coating of cobalt oxide on cold-rolled steel in alkaline sodium sulfate was Studied using the electrochemical techniques of open-circuit potential measurements and electrochemical impedance spectroscopy. The coating was prepared at different annealing temperatures ranging from 350 to 750 degreesC and characterized by SEM, EDX and XRD. Below 550 degreesC the composition of the coating was basically of Co3O4. At 750 degreesC CoO was formed and big cracks appeared on the film exposing an inner layer of iron oxides. Analysis of the EIS data is very difficult because of the complexity of the interface structure. It can be inferred that the charge transfer resistance of the coatings prepared at 350 and 450 C were higher than those for the coatings prepared at temperatures above 550 degreesC. (C) 2002 Published by Elsevier B.V. Ltd.

Acute phase protein profile in agoutis (Dasyprocta azarae; Lichtenstein, 1823) in captivity, determined by sodium dodecyl sulfate polyacrilamyde gel electrophoresis

The acute phase response refers to a nonspecific and complex systemic reaction of the organism that occurs shortly after any tissue injury. The acute phase response is considered a part of the innate host defense system, which is responsible for the survival of the host during the critical early stages of attack, and in evolutionary terms, it precedes the acquired immune response. The purpose of this study was to determine serum protein concentrations, including the acute phase protein profile in agoutis (Dasyprocta azarae) in captivity, by means of sodium dodecyl sulfate polyacrylamide gel electrophoresis. Blood samples from 11 adult healthy animals (nine females and two males) were obtained. The serum proteinogram had 21 proteins with molecular weights ranging from 15 to 240 kD. The acute phase proteins identified were: ceruloplasmin, transferrin, albumin, haptoglobin, α-1-acid glycoprotein, and hemoglobin. IgA, IgG heavy and light chains, and nonnominal identified proteins of 240, 210, 140, 98, 78, 48, 35, 31, 23, and 15 kD were also identified. The determination of the acute phase protein concentrations is a useful method for the early detection of subclinical disease or changes in the healthy animal, with predictive information on the development of disease in the future. It is possible to standardize the reference values of the serum protein profile of agoutis, which can be used for diagnosis and prognosis, treatment and clinical follow-up of nutritional disorders, and immune-mediated inflammatory diseases that may affect these animals. © 2012 Springer-Verlag London Limited.

Sodium dodecyl sulfate (SDS) effect on the thermal stability of oxy-HbGp: Dynamic light scattering (DLS) and small angle X-ray scattering (SAXS) studies

Glossoscolex paulistus (HbGp) hemoglobin is an oligomeric protein, presenting a quaternary structure constituted by 144 globin and 36 non-globin chains (named linkers) with a total molecular mass of 3.6MDa. SDS effects on the oxy-HbGp thermal stability were studied, by DLS and SAXS, at pH 5.0, 7.0 and 9.0. DLS and SAXS data show that the SDS-oxy-HbGp interactions induce a significant decrease of the protein thermal stability, with the formation of larger aggregates, at pH 5.0. At pH 7.0, oxy-HbGp undergoes complete oligomeric dissociation, with increase of temperature, in the presence of SDS. Besides, oxy-HbGp 3.0mg/mL, pH 7.0, in the presence of SDS, has the oligomeric dissociation process reduced as compared to 0.5mg/mL of protein. At pH 9.0, oxy-HbGp starts to dissociate at 20°C, and the protein is totally dissociated at 50°C. The thermal dissociation kinetic data show that oxy-HbGp oligomeric dissociation at pH 7.0, in the presence of SDS, is strongly dependent on the protein concentration. At 0.5mg/mL of protein, the oligomeric dissociation is complete and fast at 40 and 42°C, with kinetic constants of (2.1±0.2)×10-4 and (5.5±0.4)×10-4s-1, respectively, at 0.6mmol/L SDS. However, at 3.0mg/mL, the oligomeric dissociation process starts at 46°C, and only partial dissociation, accompanied by aggregates formation is observed. Moreover, our data show, for the first time, that, for 3.0mg/mL of protein, the oligomeric dissociation, denaturation and aggregation phenomena occur simultaneously, in the presence of SDS. Our present results on the surfactant-HbGp interactions and the protein thermal unfolding process correspond to a step forward in the understanding of SDS effects. © 2013 Elsevier B.V.

Mass and surface fractal in supercritical dried silica aerogels prepared with additions of sodium dodecyl sulfate

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evaluation of Sodium Lauryl Sulfate as a Blackbird Wetting Agent

New and improved strategies are needed for managing overabundant blackbird (Icteridae spp.) populations in some areas of the United States. From 2004 to 2007, we evaluated sodium lauryl sulfate (SLS) as a wetting agent during controlled outdoor cage and flight pen tests in Colorado and small-scale field tests at urban blackbird roosts in Missouri. In the outdoor cage tests (ambient temperature -5 to 2° C), mortality of male red-winged blackbirds (Agelaius phoeniceus) sprayed with 1, 2, and 5 ml of SLS on the back feathers only, on the breast feathers only, or on both breast and back feathers ranged from 25% to 100%. A SLS spray on male red-winged blackbirds at 2° C ambient temperature with 1 ml of SLS sprayed on breast feathers and back feathers resulted in 90% mortality in less than 60 minutes. In a flight pen test (-12 to -5° C ambient temperature ), SLS sprayed at 20 l per 3,400 l of water with a single ground-based sprinkler-head system over 35 male red-winged blackbirds roosting in cedar trees (Juniperus virginiana) resulted in 53% mortality. There was no mortality in the control group exposed to the same treatment without the SLS. Small-scale field tests conducted in Missouri at 6 sites with a single ground-based sprinkler-head spray system and at 2 sites with 4 sprinkler-head spray systems resulted in mortality that ranged from 0 to 4,750 and 4,500 to 15,000 blackbirds and starlings, respectively. Spray operations lasted from 28 to 208 minutes. Each spray covered about 200 m2 . At all sites, mortality of blackbirds sprayed with the SLS occurred as soon as 30 minutes post-SLS application. Mortality at two sites where pump problems precluded completing the spray ranged from 0 to 800 birds. Air leaving the system as the system was activated caused birds to flush from the roost trees. Poor water quality and pump durability were problems at some sites.

Adsorption of Sodium Dodecyl Sulfate on Ge Substrate: The Effect of a Low-Polarity Solvent

This paper describes the adsorption of sodium dodecyl sulfate (SDS) molecules in a low polar solvent on Ge substrate by using Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy and atomic force microscopy (AFM). The maximum SDS amount adsorbed is (5.0 +/- 0.3) x 10(14) molecules cm(-2) in CHCl3, while with the use of CCl4 as subphase the ability of SDS adsorbed is 48% lower. AFM images show that depositions are highly disordered over the interface, and it was possible to establish that the size of the SDS deposition is around 30-40 nm over the Ge surface. A complete description of the infrared spectroscopic bands for the head and tail groups in the SDS molecule is also provided.

The influence of sulfuric environments on concretes elaborated with sulfate resistant cements and mineral admixtures. Part 1: Concrete exposed to Sodium Sulfate (Na2SO4) = Estudio de la influencia de los medios con presencia de sulfatos en hormigones con cementos sulforresistentes y adiciones minerales. Parte 1: Hormigones expuestos a sulfato sódico (Na2SO4)

The study of sulfate attack in concrete is considered vital for the preservation of the structural integrity of constructions. Its aggressive behaviour causes degradation of the cement matrix which changes the initial properties of the material. In this article, the sulfate resistance of concrete is studied. To that goal, four different concrete mixes were made with sulphur resistant cement. The concretes were tested for compressive strength, transport capacity of sulfates and microstructural properties. An experimental program was proposed in which the concrete samples were submerged in sodium sulphate (Na2SO4) solution. The obtained results were compared with reference values of concretes cured in calcium hydroxide [Ca(OH)2]. According to the results the concrete with ground granulated blast-furnace slag presented the best behavior when exposed to sodium sulphate (Na2SO4) solution. El estudio del ataque de sulfatos en el hormigón se considera de gran importancia para la conservación de la integridad estructural de las construcciones. Su agresividad se basa en la degradación de la matriz cementicia modificando las características iniciales de diseño. En el presente trabajo se estudia la resistencia del hormigón al ataque de sulfatos provenientes de sulfato sódico (Na2SO4). Para llevar a cabo la investigación se diseñaron cuatro dosificaciones de hormigón empleando cementos sulforresistentes y adiciones minerales. Se llevó a cabo una propuesta experimental donde las muestras de hormigón se sumergieron en disolución de sulfato sódico (Na2SO4) de concentración 1M. Posteriormente se realizaron ensayos de resistencia mecánica, capacidad de transporte de sulfatos y propiedades microestructurales, a distintas edades. Los resultados obtenidos se compararon con valores de referencia de mezclas de hormigón curadas expuestas a hi-dróxido cálcico [Ca(OH)2]. De acuerdo a los resultados obtenidos, el hormigón con escoria de alto horno presentó las mejores características de durabilidad frente a sulfatos provenientes de sulfato sódico

North Dakota sodium sulfate deposits /

Mode of access: Internet.

Disruption of NaS1 sulfate transport function in mice leads to enhanced acetaminophen-induced hepatotoxicity

Sulfate is required for detoxification of xenobiotics such as acetaminophen (APAP), a leading cause of liver failure in humans. The NaS1 sulfate transporter maintains blood sulfate levels sufficiently high for sulforiation reactions to work effectively for drug detoxification. In the present study, we identified two loss-of-function polymorphisms in the human NaS1 gene and showed the Nas1-null mouse to be hypersensitive to APAP hepatotoxicity. APAP treatment led to increased liver damage and decreased hepatic glutathione levels in the hyposulfatemic Nas1-null mice compared with that in normosulfatemic wild-type mice. Analysis of urinary APAP metabolites revealed a significantly lower ratio of APAP-sulfate to APAP-glucuronide in the Nas1-null mice. These results suggest hyposulfatemia increases sensitivity to APAP-induced hepatotoxicity by decreasing the sulfonation capacity to metabolize APAP. In conclusion, the results of this study highlight the importance of plasma sulfate level as a key modulator of acetaminophen metabolism and suggest that individuals with reduced NaS1 sulfate transporter function would be more sensitive to hepatotoxic agents.