Evaluation of eggshell membrane-based bio-adsorbent for solid-phase extraction of linear alkylbenzene sulfonates coupled with high-performance liquid chromatography

The potential of eggshell membrane (ESM) as a novel solid-phase extraction bio-adsorbent was investigated in the present study. The ESM with a unique structure of intricate lattice network showed a predominant ability to capture linear alkylbenzene sulfonates (LAS) as a model of organic pollutants by the hydrophobic interactions between ESM and LAS molecular at pH very close to the isoelectric point of ESM, which was similar to the most widely used trapping mechanism for SPE. Under the optimal conditions, the breakthrough capacities of the ESM packed cartridge for C10–C13 LAS homologues were found to be 30, 53, 50, and 43 μg g⁻¹, respectively. On the basis of high-performance liquid chromatography separation and UV detection of LAS homologues, the proposed system could respond down to 0.027 ng mL⁻¹ of LAS with a linear calibration range from 0.2 to 100 ng mL⁻¹, showing a good LAS enrichment ability of eggshell membrane biomaterial with high sensitivity, and could be successfully used for the detection of residual LAS in environmental water samples. The reproducibility among columns was satisfactory (RSD among columns is less than 10%). A comparison study with ESM, C8 and C18 as adsorbents for LAS demonstrated that ESM-based bio-adsorbent was advantageous over C8 and C18, the widely used traditional adsorbents.     

Determination and Characterization of Photocatalytic Products of Linear Alkyl Sulphonate by High Performance Liquid Chromatography and Nuclear Magnetic Resonance

In this study, Linear Alkyl Sulfonate (LAS) as anionic detergent active compounds was treated with photocatalytic method. The method degrades LAS to form CO₂ and H₂O. Time variations performed to the photocatalysis was conducted hour to hour, from 1 to 5 hours. Determination of LAS concentration was carried out using methylene blue active substances (MBAs), whereas characterization of LAS structure was observed using high performance liquid chromatography (HPLC) and nuclear magnetic resonance spectrometry (NMR). The results showed that 69.9% of LAS decomposes 65.1% of CO₂ are formed.     

Ion-pair extraction and GC-MS determination of linear alkylbenzene sulphonates in aqueous environmental samples

A GC-MS method was developed for the determination of linear alkylbenzene sulphonates (LAS) and sulphophenylcarboxylic acids (SPC) in aqueous environmental samples. LAS and SPC were isolated from aqueous samples using methylene green (MG) as ion-pair reagent and derivatised with diazomethane for their chromatographic analysis. LAS and SPC were then analysed with GC-MS in EI mode as their methyl esters. The method eliminates positive and negative interferences found by the methylene blue method and considered to be selective and sensitive for the determination of LAS and SPC in aqueous samples. The recovery of LAS was 98% with a relative standard deviation (R.S.D.) of 2.0% and the detection limit obtained from calculations by using GC-MS results based on S/N:3 was lower than 10 ppb. Obtained results revealed that the method can also be employed in the analysis of organic compounds bearing sulphate and sulphonate groups.     

Surface Plasmon Resonance Immunosensor for Anionic Surfactants Based on an Indirect Competitive Immunoreaction

Abstract

A highly sensitive surface plasmon resonance immunosensor for the determination of linear alkylbenzene sulfonate (LAS) was fabricated. The method is based on an indirect competitive reaction of an anti‐LAS antibody in a sample solution with LAS immobilized on a sensor chip and with LAS in the sample solution. A sensor chip immobilized with LAS was prepared by utilizing an electrostatic interaction between an LAS conjugate, LAS–horseradish peroxidase (LAS‐HRP), and a self‐assembled monolayer of 11‐amino‐1‐undecanethiol hydrochloride, which was preliminary prepared on a gold thin film of the sensor chip. The quantitative determination of LAS in the concentration range 10–1000 ppb was achieved by using the proposed immunosensor.     

Determination of linear alkylbenzene sulfonates by ion-pair solid-phase extraction and high-performance liquid chromatography

In this paper, the potential use of multiwalled carbon nanotubes (MWCNTs) as solid phase extraction (SPE) adsorbent was evaluated for preconcentration of linear alkylbenzene sulfonates (LAS) using ion-pair (IP)-SPE with tetrabutylammonium hydroxide (TBAH). The LAS homologues present in the aqueous sample were ion-paired with TBAH and the solution was passed through the MWCNT cartridges. The analytes retained in the cartridge were eluted with methanol and the concentrated methanol extract was analysed by HPLC-UV. In order to obtain the satisfactory recovery of LAS homologues, various parameters including the type and amount of the ion-pair reagents, the desorption and enrichment conditions such as the effect of eluent and its volume, pH, the flow rate, the ultrasonic time of sample, and the volume of sample solution were systematically optimized. Under the optimal conditions, LAS homologues could be easily extracted by the proposed SPE cartridge. The favorable limits of detection (LOD) for LAS homologues were in the range from 0.02 to 0.03 μg L⁻¹, and the relative standard deviations (RSDs) were 1.55-2.54% for 10 μg L⁻¹ LAS (n = 6). The proposed method has been successfully applied for the analysis of LAS homologues in aqueous environmental samples. A comparison study with ion-pair solid extraction on MWCNTs, C8 and C18 as adsorbents for LAS demonstrated that ion pair-based solid extraction on MWCNTs adsorbent was advantageous over C8 and C18, the widely used traditional adsorbents.     

Assessment of the hemolysis and endothelial cell cytotoxicity induced by residual linear alkylbenzene sulfonates on pharmaceutical rubber stoppers based on HPLC‐ESI‐MS

This study was designed to develop a high‐performance liquid chromatographic–electrospray ionization–mass spectrometry (HPLC‐ESI‐MS) method for quantitative determination of residual surfactant linear alkylbenzene sulfonate (LAS) compounds on pharmaceutical rubber stoppers. An HPLC‐ESI‐MS method was developed for separation and determination of five LAS homologs (C10–C14) under gradient conditions using methanol and ammonium acetate as mobile phases. Hemolysis activity of residual LAS compounds was analyzed by spectrophotometry. Expression of interleukin (IL)‐6 and tumor necrosis factor (TNF)‐α in human umbilical vein endothelial cells (HUVECs) after LAS compound treatment was examined by enzyme‐linked sorbent assay. LAS compounds were well separated and determined by the established gradient conditions. The linear range was 0.05–8 µg/mL with correlation coefficients ≥0.997. Recoveries were from 73 to 134% and the relative standard deviation was <13.7%. There was a correlation between hemolysis rate and LAS compounds concentration when it was ≥0.8 µg/cm². LAS compounds decreased the viability of HUVECs and promoted the production of IL‐6 and TNF‐α. The developed analytical method was successful for quantitative determination of residual LAS compounds on pharmaceutical rubber stoppers and it is important to monitor and control the amount of LAS compounds on rubber stoppers. Copyright © 2015 John Wiley & Sons, Ltd.     

The role of electrolyte and polyelectrolyte on the adsorption of the anionic surfactant, sodium dodecylbenzenesulfonate, at the air-water interface

The role of the polyelectrolyte, poly(ethyleneimine), PEI, and the electrolytes NaCl and CaCl(2), on the adsorption of the anionic surfactant, sodium dodecylbenzenesulfonate, LAS, at the air-water interface have been investigated by neutron reflectivity and surface tension. The surface tension data for the PEI/LAS mixtures are substantially affected by pH and the addition of electrolyte, and are consistent with a strong adsorption of surface polymer/surfactant complexes down to relatively low surfactant concentrations. The effects are most pronounced at high pH, and this is confirmed by the adsorption data obtained directly from neutron reflectivity. However, the effects of the addition of PEI and electrolyte on the LAS adsorption are not as pronounced as previously reported for PEI/SDS mixtures. This is attributed primarily to the steric hindrance of the LAS phenyl group resulting in a reduction in the ion-dipole attraction between the LAS sulfonate and amine groups that dominates the interaction at high pH.     

Linear alkyl benzene sulphonate (LAS) degradation by immobilized Pseudomonas aeruginosa under low intensity ultrasound

We studied the LAS degradation of immobilized Pseudomonas aeruginosa with low-intensity ultrasonic and the influence of original LAS concentration, pH, rotary velocity and different conditions of low-intensity ultrasonic irradiation on the degradation of LAS. In our experiment, the degradation rate of LAS was the main index. We found that low-intensity ultrasonic irradiation could improve the metabolism of microorganism cells and promote the LAS biodegradation of immobilized cells. In the experiment, 50 mg/l LAS were used to simulate wastewater, and low-intensity ultrasonic was considered. We found the influence was obvious, and the optimal degradation rate was acquired when the conditions of ultrasonic were frequency 24 kHz, power 8 W, stimulation time 5 s, intermissive time 30 s, and total time 10 min. The LAS degradation rate of immobilized cells with ultrasonic were respectively 40% and 9.5% higher than that of the suspending cells and immobilized cells without irradiation.     

Determination of the four major surfactant classes in cleaning products by reversed-phase liquid chromatography using serially connected UV and evaporative light-scattering detection

A method for the simultaneous determination of the most frequently used surfactant families –linear alkyl benzenesulphonates (LAS), alkyl ether sulphates (AES), fatty alcohol ethoxylates (FAE) and oleins (soaps, fatty acid salts) – in cleaning products, has been developed. The common reversed phase octyl (C8), pentafluorophenyl and biphenyl columns were not capable of separating the anionic LAS and AES classes; however, since only LAS absorbs in the UV, these two classes were independently quantified using a C8 column and serially connected UV and ELSD detection. The best compromise to resolve the four surfactant classes and the oligomers within the classes was achieved with a C8 column and an ACN/water gradient. To enhance retention of the anionic surfactants, ammonium acetate, as an ion-pairing agent compatible with ELSD detection, was used. Also, to shift the olein peaks with respect to that of the FAE oligomers, acetic acid was used. In the optimized method, modulation of the mobile phase, using ammonium acetate during elution of LAS and AES, and acetic acid after elution of LAS and AES, was provided. Quantitation of the overlapped LAS and AES classes was achieved by using the UV detector to quantitate LAS and the ELSD to determine AES by difference. Accuracy in the determination of AES was achieved by using a quadratic model, and by correcting the predicted AES concentration according to the LAS concentration previously established using the UV chromatogram. Another approach also leading to accurate predictions of the AES concentration was to increase the AES concentrations in the samples by adding a standard solution. In the samples reinforced with AES, correction of the predicted AES concentration was not required. FAE and olein were quantified using also quadratic calibration.     

Development of Methodologies for Different Degrees of Resolution of Linear Alkylbenzene Sulfonates in Groundwater and Wastewater by Liquid Chromatography Using Sodium Dodecyl Sulphate

Linear alkylbenzenesulfonates (LAS) are used extensively as surfactants in consumer formulations as a complex mixture of homologues and isomers. Separation of homologues and isomers of LAS is important in industrial and environmental samples in order to establish their behaviour. Here we present a HPLC methodology with fluorescent detection (FD) for the determination of the homologues and isomers as well as the sum of LAS present. The quantification of total LAS was achieved without a column, using the liquid chromatograph as a FIA system. The different homologues were separated using a Lichrospher-100 RP-8 column of 125 × 4 mm using a linear gradient of methanol and 30.0 mM sodium dodecyl sulphate (SDS), increasing the methanol content linearly from 55% to 70% in 16 min. The resolution of isomers was carried out by using two coupled Lichrospher-100 RP-18 columns of 250 × 4 mm. Elution of isomers was done with a gradient of flow rate from 1.0 to 0.25 mL min^–1 using a linear gradient of acetonitrile and 5.0 mM SDS increasing the acetonitrile content linearly from 20% to 40% in 160 min. The methods were validated and applied satisfactorily to the determination of LAS in urban wastewater and ground water.     

Mixing behavior of the biosurfactant, rhamnolipid, with a conventional anionic surfactant, sodium dodecyl benzene sulfonate

The use of small angle neutron scattering, SANS, neutron reflectivity, NR, and surface tension to study the mixing properties of the biosurfactant rhamnolipid with a conventional anionic surfactant, sodium dodecyl 6-benzene sulfonate, LAS, is reported. The monorhamnose rhamnolipid, R1, mixes close to ideally with LAS at the air-water interface, whereas for mixtures of LAS with the dirhamnose rhamnolipid, R2, the LAS strongly partitions to the air-water interface relative to R2, probably because of the steric hindrance of the larger R2 headgroup. These trends in the binary mixtures are also reflected in the ternary R1/R2/LAS mixtures. However, for these ternary mixtures, there is also a pronounced synergy in the total adsorption, which reaches a maximum for a LAS/rhamnolipid mole ratio of about 0.6 and a R1/R2 mol ratio of about 0.5, an effect which is not observed in the binary mixtures. In solution, the R1/LAS mixtures form relatively small globular micelles, L(1), at low surfactant concentrations (<20 mM), more planar structures (lamellar, L(α), unilamellar/multilamellar vesicles, ulv/mlv) are formed at higher surfactant concentrations for R1 and LAS rich compositions, and a large mixed phase (L(α)/L(1) and L(1)/L(α)) region forms at intermediate surfactant compositions. In contrast, for the R2/LAS mixtures, the higher preferred curvature of R2 dominates the phase behavior. The predominant microstructure is in the form of small globular micelles, except for solution compositions rich in LAS (>80 mol % LAS) where more planar structures are formed. For the ternary mixtures, there is an evolution in the resulting phase behavior from one dominated by L(1) (R2 rich) to one dominated by planar structures, L(α), (R1, LAS rich), and which strongly depends upon the LAS/rhamnolipid and R1/R2 mole ratio.     

Determination of linear alkylbenzenesulfonates in communal wastewater by means of solid phase microextraction coupled with API-MS and HPLC-FLD

The use of Solid Phase Microextraction (SPME) for the qualitative and quantitative determination of Linear Alkylbenzenesulfonates (LAS) in waste water samples was investigated. A Carbowax/Templated Resin (CW/¶TPR) coated fiber was directly immersed into influent and effluent samples of a sewage treatment plant (STP). Extraction conditions such as time, pH, ion strength were investigated. The extracted LAS were desorbed with a solvent in a specially designed SPME-LC interface for analysis with HPLC-FLD and Electrospray Ionization Mass Spectrometry (ESI-MS). The combination of SPME with ESI-MS proved to be an alternative technique for the LAS determination in waste water. Linear ranges of the external calibration were found from 0.5–100 ng/mL, with detection limits of 0.5 ng/mL for each individual LAS homologue. The reproducibility of the method is 15% (relative standard deviation).     

Analysis of traces of surfactants in water with anion-exchange resin and polymeric adsorbent

Summary Determination of traces of anionic and non-ionic surfactants in water has been based on the quantitative separation of sodium alkylbenzene sulphonate (LAS) from polyoxyethylenealkylphenyl ether (APE) with a weak base anion-exchange resin, and adsorption of APE in filtrate with Amberlite XAD-2 resin. LAS is adsorbed on the anionexchange resin, eluted with hydrochloric acid-methanol and determined spectrophotometrically by methylene blue or UV absorption. APE in the filtrate is adsorbed on XAD-2 resin, eluted with methanol and determined spectrophotometrically by cobalt thiocyanate or UV absorption. Recoveries of surfactants were about 90100%. As little as 0.02 ppm can be determined. In a river water sample 0.06 ppm of LAS and 0.05 ppm of APE and in another case, 0.12 ppm of LAS and 0.07 ppm of APE were found.

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Spurenanalyse von oberflächenaktiven Substanzen in Wasser mit Hilfe eines Anionenaustauschers und eines Polymeradsorbens

Zusammenfassung Natriumalkylbenzolsulfonat (LAS) kann von Polyoxyethylenalkylphenylether (APE) getrennt werden, indem LAS an einem schwachbasischen Anionenaustauscher und im Filtrat APE an Amberlit XAD-2 adsorbiert wird. LAS wird mit Methanol-HCl eluiert und im Eluat spektralphotometrisch mit Methylenblau oder durch UV-Absorption bestimmt. APE wird mit Methanol eluiert und spektralphotometrisch mit Cobaltthiocyanat oder ebenfalls durch UV Absorption bestimmt. Bei Zusatzversuchen wurden 90–100% wiedergefunden. Bis zu 0.02 ppm können bestimmt werden. In einer Flußwasserprobe wurden 0,06 ppm LAS und 0,05 ppm APE bzw. 0,12 ppm LAS und 0,07 ppm APE gefunden.

     

环烷酸铅和烷基水杨酸铅的微波原位合成及其摩擦学性能

在液体石蜡中采用微波技术原位合成了油溶性环烷酸铅(LN)和十二烷基水杨酸铅(LAS).在高速低负荷(r=1500±10 rpm、 P=196～392 N)和低速高负荷(r=300±10 rpm、 P=800 N)两种条件下,用四球摩擦磨损试验对LN、 LAS和对应的羧酸进行了摩擦学性能评价,用往复式摩擦试验机考察了LN和LAS抗磨减摩性能.结果表明: LN具有良好的抗磨减摩性能和中等的极压性能,且各项摩擦学性能指标均好于LAS.为弄清其作用机理,从分子结构分析了产生摩擦学性能差异的原因,并用SEM及XPS研究了磨斑表面.结果发现: 摩擦过程中, LN和LAS都能在摩擦副表面形成吸附膜且部分吸附膜发生摩擦化学反应产生了铅氧化物转化膜,但所形成的吸附膜和转化膜厚度不同.     

Regulating the physicochemical and catalytic properties of layered aluminosilicates

Basic methods of the introduction of metal ions into the interlayer space of natural layered aluminosilicate (LAS) are considered. The physicochemical and structural properties of pillared LAS’s depend on the nature of the cation, as well as on the cation intercalation method and conditions. The catalytic properties and stability of an LAS in acid-catalyzed and oxidation reactions may depend on its textural and physicochemical properties.     

Effects of initial concentration of LASs on the rates of sonochemical degradation and cavitation efficiency

The effect of initial concentration of linear alkylbenzene sulfonate (LAS: p-octylbenzene sulfonate (LAS C₈), p-nonylbenzene sulfonate (LAS C₉), p-dodecylbenzene sulfonate (LAS C₁₂)) on the rate of sonochemical degradation was investigated over a wide concentration range under Ar atmosphere by 200 kHz ultrasonic irradiation. The degradation rate of each LAS increased with increasing initial concentration of LAS and then started to decrease with the different behavior depending on the types of LASs. This result indicated that the cavitation efficiency was gradually changed by their concentrations and the optimum LAS concentrations for their effective degradation existed. The maximum degradation rates were observed at 250 μM of LAS C₁₂, 1250 μM of LAS C₉, and 2500 μM of LAS C₈, respectively. These optimum concentrations were found to be about four to six times smaller than these critical micelle concentrations (CMCs). It was also found that the maximum degradation rates at the optimum concentrations were observed to be almost linearly correlated with their CMCs. Based on the obtained results, it could be suggested that the micelle formation occurs in the interfacial region of cavitation bubbles during rectified diffusion and this phenomenon reduces the cavitation efficiency. In addition, from the results of the rate of the sonochemical degradation of LASs and the yield of hydrogen peroxide, the existence of thermal gradient in the interfacial region of cavitation bubbles was also confirmed.     

Freely dissolved concentrations of anionic surfactants in seawater solutions: Optimization of the non-depletive solid-phase microextraction method and application to linear alkylbenzene sulfonates

A solid-phase microextraction method (SPME) has been optimized for the analysis of freely dissolved anionic surfactants, namely linear alkylbenzene sulfonates (LAS), in seawater. An effect of the thermal conditioning treatment on the polyacrylate fiber coating was demonstrated for both uptake kinetics and sorption isotherm linearity. Thermal conditioning at 120 °C yielded linear sorption isotherms and reproducible SPME measurements for several individual LAS compounds, with detection limits at the low microgram per liter range. Sorption of LAS to the conditioned SPME fiber was independent of LAS co-solutes in mixtures. The method has been applied to study the precipitation of LAS in seawater, and solubility data for a wide range of individual LAS constituents is presented for the first time. Hence, the developed SPME method for the anionic LAS has shown to be a useful tool in complex matrices. The advantage of the SPME analyses in complex matrices is, besides its simplicity, that it also leads to clean extracts for chromatographic analyses.     

Carboxyl modified multi-walled carbon nanotubes as solid-phase extraction adsorbents combined with high-performance liquid chromatography for analysis of linear alkylbenzene sulfonates

Recently, multi-wall carbon nanotubes (MWCNTs) as adsorbents of solid-phase extraction are attractive because they can be used for enrichment of organic compounds and metal ions at trace levels. In this study, we use the carboxyl modified multi-wall carbon nanotubes (CMMWCNTs) as adsorbents of solid-phase extraction for extraction of linear alkylbenzene sulfonates (LAS), which are widely used anion surfactant with different homologues, and detected by HPLC-UV. The effect of eluent and its volume, sample pH and flow rate, sample volume and the ultrasonic time of sample, the content of the electrolyte (NaCl) were investigated and optimized. The detection limit for LAS homologues was 0.02-0.03 μg L⁻¹ with R.S.D. (n = 6) ranging from 2.04 to 10.03%. The recoveries of LAS homologues in the spiked environmental water samples ranged from 84.8 to 106.1%. The proposed method has been applied successfully to the analysis of LAS in aqueous environmental samples, which demonstrates that CMMWCNTs-based solid-phase extraction is a precision and convenient enrichment method and can be used for analysis of LAS homologues in water samples.     

Extraction and determination of linear alkylbenzenesulfonate detergents from the aquatic environment using a membrane disk and gas chromatography

Levels of linear alkylbenzenesulfonate (LAS) detergents have been measured in Anzali lagoon water sampled at fourteen stations. All samples were extracted with octadecyl-bonded silica membrane disks. Extraction efficiency, maximum capacity, and the effect of the solvent used to extract the LAS from the membrane disks were evaluated. Extraction efficiencies > 95% were obtained by elution of the disks with minimal amounts of solvent. It was demonstrated that membrane disk extraction introduced less error into analytical results than liquid – liquid extraction. Quantitative determination of total LAS levels and measurement of the distribution of LAS homologs with C₁₀? C₁₃ alkyl chains were performed by high resolution gas chromatography with flame ionization detection after derivatization of the detergents with sulfonyl chloride. The total level of LAS ranged from 0.01 to 0.89 ppm.     

Determination of linear alkylbenzene sulfonates and their polar carboxylic degradation products in sewage treatment plants by automated solid-phase extraction followed by capillary electrophoresis-mass spectrometry.

Linear alkylbenzene sulfonates (LAS) were determined by solid-phase extraction (SPE), followed by capillary electrophoresis and mass spectrometry detection (CE-MS). The linear range of the proposed method varied from 33 to 316 and from 215 to 2057 micrograms L-1, depending on the compound, with limits of detection ranging from 4.4 to 23 micrograms L-1 when 200 ml of wastewater were preconcentrated. The analysis and confirmation of the polar carboxylic metabolites of LAS, the sulfophenyl carboxylic acids (SPC) was also achieved, and their presence was detected in both, influent and effluents of the sewage treatment plant (STP). [M - H]- ions were used for CE-MS confirmation and quantification. CE-MS diagnostic ions were the same ones used in LC-electrospray (ESI)-MS and corresponded to m/z 297, 311, 325 and 339 for C10LAS, C11LAS, C12LAS and C13LAS, respectively. For SPC identification, diagnostic ions corresponded to m/z 215 to 369 (with 14 mass unit steps) for C2 to C13SPC, respectively. LAS were determined in wastewater samples of the influent and effluent of three sewage treatment plants (STP), two of them using biological treatment with secondary settlement and receiving mainly domestic wastewater whereas one of the plants was operated with physiochemical treatment and received mainly industrial wastewater. The concentration levels of total LAS varied from 1000 to 1900 micrograms L-1 in the influents of STP, whereas in the effluents the concentrations varied from 125 to 360 micrograms L-1.