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Ethoxylation is one of the common industrial process in which ethylene oxide (EO) is added to compounds containing active hydrogen atom (OH, COOH, SH, NH, etc.) to form surfactants. Alcohol ethoxylates are a major class of non‐ionic surfactants composed of an alkyl chain combined with few EO units. They are widely used in homecare products, personal care products, textiles, oilfield, construction, lubricants, food, paper, leather. The analysis of these ethoxylates possess several challenges since they contain 'n' number of EO units (n > 1). With increase in "n," the product becomes more and more viscous and the boiling point increases making it difficult to analyze by normal gas chromatography (GC) technique. This paper describes a method of derivatizing these ethoxylates so that they can be eluted on a high temperature GC. BSTFA (N, O‐bis (trimethylsilyl) trifluoroacetamide) is used as the derivatizing agent (silylating agent). The ethoxylate combines with BSTFA to form the corresponding trimethylsilylated (TMS) product, which have comparatively lower boiling point. Thus, we detect trimethyl silyl product, which is the resemblance for the ethoxylated product. In this paper, we present a quantitative GC method for the ethoxylates of a few simple alcohols (2‐ethyl hexanol, glycerin), and complex vegetable oils (castor oil). The products formed during the reaction have also been identified on a gas chromatograph coupled with mass spectrometer (GCMS). GCMS shows the mass corresponding to the TMS derivatized product. The derivatization technique not only helps in increasing the volatility of these compounds but also improves the chromatographic efficiency, selectivity, and enhances the detectability. [ABSTRACT FROM AUTHOR]

In this study, an optimized method was presented for the reverse quartz flotation in iron ore purification where sodium oleate (NaOL) was always selected as the collector due to its accessibility and economic benefits. Three alcohol ethoxylates, octylphenol ethoxylate (OP-10), nonylphenol ethoxylate (NP-10) and fatty alcohol ethoxylates (AEO-9) were introduced to improve the collecting performance of NaOL in the reverse flotation of quartz. It turned out that the addition of alcohol ethoxylates was helpful to increase the recovery of quartz in the flotation with the order of OP-10 > NP-10 > AEO-9. To characterize the adsorption of NaOL on activated quartz in different surfactant systems, Fourier-Transform Infrared Spectroscopy (FTIR) and Quartz Crystal Microbalance with Dissipation (QCM-D) were employed. Furthermore, the contact angles of the quartz surface that interacted with different surfactant systems were measured to investigate the synergy effect of NaOL and alcohol ethoxylates on the hydrophobicity of quartz. It turned out that alcohol ethoxylates promoted the adsorption of NaOL on the activated quartz, resulting in an increase in the hydrophobicity of quartz also in the order of OP-10 > NP-10 > AEO-9, which well explained the flotation results. Regular Solution Theory (RST) and the dilution effect based on the surface tension analysis were utilized to elucidate the synergy mechanism between NaOL and the alcohol ethoxylate. [ABSTRACT FROM AUTHOR]

Alcohol ethoxylates (AE) are commonly used nonionic surfactants with widespread adoption in consumer and industrial applications. The toxicology profile of this general class of molecules has been extensively reported previously. This report serves to make accessible previously unpublished toxicological data from 59 toxicology studies on AE produced from branched and semilinear alcohols produced by ExxonMobil, with alcohol backbones ranging from C9 to C15. Information on acute oral toxicity, acute dermal toxicity, genetic toxicity, skin irritation, eye irritation, skin sensitization, and oral repeat‐dose toxicity are presented here. These data significantly enrich the database on the toxicity of branched AE and support that the degree of branching presents no unique toxicological hazards in relation to that of semilinear AE in this report, as well as in comparison with similar data published on a range of linear, semilinear, and branched AE. [ABSTRACT FROM AUTHOR]

With the advent of global regulations for safer detergent and an emphasis on a shift toward more environmentally friendly formulations, the environmental profile of surfactant chemistries have moved to the forefront of product formulation and design. The two cornerstones of surfactant environmental profiles are the ability to biodegrade in the natural environment and the ecological hazard profile. The objectives of this article are to describe biodegradation and aquatic toxicity data for a series of branched oxo‐alcohol ethoxylate (AEO) surfactants; to apply the target lipid model (TLM) for deriving model‐based threshold hazard concentrations (HC5) of AEO; and, finally, to accurately determine aquatic classifications for AEO surfactants for use in regulatory classification frameworks. Biodegradation results indicate a high level of biodegradability of branched AEO, with C8–C13‐rich oxo‐alcohols with 1–20 mol of ethoxylate meeting the readily biodegradable criteria. Results from acute and chronic toxicity tests indicated comparable or lesser aquatic toxicity versus linear AEO structures previously reported in the literature. The TLM model, applied a priori, resulted in good agreement with acute toxicity data (RMSE = 0.49) and is comparable to the root mean square errors (RMSE) previously determined for other narcotic chemicals (RMSE = 0.46–0.57). Model errors for invertebrates and fish were smaller than those for algae, with the TLM systematically overpredicting acute and chronic classification of two of seven branched AEO. Furthermore, TLM‐predicted HC5 values were determined to be sufficiently conservative, with 100% of observed chronic data (N = 79) falling above the HC5 threshold values, providing a useful tool for the risk assessment of AEO. [ABSTRACT FROM AUTHOR]

• A series of bimetallic catalysts based Au-Cu supported over nanoceria were prepared. • A 80% yield to AECA6 was achieved in the oxidation reaction of AEO7 with H 2 O 2. • The formation of a AuCu alloy at a Cu/Au molar ratio of 0.11 on Au enhances the catalytic activity. • The catalyst can be recycled and reused for at least 10 consecutive runs without loss of activity. • Cu on Au favors the adsorption of AEO7, H 2 O 2 and OH− on the catalyst surface compared to pure Au. • Isolated Cu sites on the AuCu alloy appear as crucial for enhancing the catalytic activity. We describe in this work the preparation of a series of bimetallic Au-Cu catalysts supported over nanoceria for the direct oxidation of C 12 -C 14 -alcohol polyethyleneglycol ether with on average 7 ethyl oxide units (AEO7) to polyoxyethylene lauryl ether carboxylic acid (AECA6), using H 2 O 2 as an oxidant, under basic conditions. Different preparation methods have been used, including deposition-precipitation, incipient wetness impregnation and wet impregnation for engineering the interaction between Au, Cu and nanoceria. The structure of the bimetallic catalysts is discussed in detail on the basis of refined characterization by XRD, HR-TEM, STEM-EDX-SDD, XPS and ICP-AES. The formation of a AuCu alloy over nanoceria at a Cu/Au molar ratio of 0.11 on Au allows a significant enhancement of the catalytic activity, resulting in an AECA6 yield up to 80% with a selectivity of 90%. The catalyst can be recycled and reused for at least 10 consecutive runs without apparent loss of activity. Detailed DFT calculations on Au, Cu and Au-Cu model alloys reveal a positive role of Cu on Au by favoring the adsorption of AEO7, H 2 O 2 and OH− on the catalyst surface compared to pure Au, as well as by reducing the energy barrier for H 2 O 2 cleavage. Isolated Cu sites on the Au-Cu alloy appear as crucial for enhancing the catalytic properties for AEO7 oxidation. [ABSTRACT FROM AUTHOR]

This report describes the application of LC-MS/MS for the separation of dodecanol (COH) and homogenous fatty alcohols ethoxylated (AE) containing a dodecyl moiety and 1-9 ethoxy groups. These ethoxylates and free alcohol were derivatized for LC-MS/MS analysis with phenyl isocyanate (PIC). The derivatives of analytes with PIC were separated using a C18 column. Gradient elution with a mixture of ethyl acetate and acetonitrile (5 mM) was employed. The described determination method is characterized by low detection limits (range from 0.005 µg L for: COH, CEO to 1 µg L for CEO) and quantification limits (range from 0.01 µg L for: CEO to 2 µg L for CEO). The developed and validated method was used in combination with liquid-liquid extraction (using ethyl acetate) in order to identify and quantitatively determine the COH and CEO present in environmental samples collected from Warta river water in Poznan. Graphical abstract: [ABSTRACT FROM AUTHOR]

• Apatite flotation with polyoxyethylene cetyl ether with 2 EO groups is enhanced. • Feed containing >85 % particles passing 36 µm can be successfully treated. • The process recovers 45.5 % P 2 O 5 to a concentrate grade of 31.2 % from 9.1 % P 2 O 5 feed. This work presents the results obtained during flotation of fine-grained apatite-bearing tailings provided from the Kovdor concentration plant in a laboratory cell and a pilot-scale column. Flotation studies were conducted on a sample containing >85 % particles passing 36 µm by using tall oil fatty acids in combination with polyoxyethylene cetyl ether (2 EO groups) as an alternative for nonylphenol ethoxylates. 45.5 % P 2 O 5 recovery to a concentrate grade of 31.2 % P 2 O 5 from 9.1 % P 2 O 5 feed was achieved after rougher and one cleaner stage in a pilot-scale column using the mixed collector with phosphate modifier and starch as depressor. [ABSTRACT FROM AUTHOR]

Using dielectric relaxation spectroscopy (DRS), small-angle X-ray scattering (SAXS), dynamic light scattering (DLS), and viscometry, we have investigated the hydration behavior, static structures, Brownian dynamics, and mechanical properties of aqueous solutions of alcohol ethoxylate (C12E15) and methyl ester ethoxylate (C12MEE), hereafter abbreviated as AE and MEE, respectively, in which we especially focus on the effects of the endcaps of these nonionic surfactants. We find that AE and MEE exhibit fairly different phase behaviors in water: AE produces liquid crystalline phases at w (surfactant weight fraction) > 0.35, whereas MEE retains a liquid phase in an extremely wide concentration range (w < 0.7) at ambient temperature. The structure factor deduced from SAXS intensities using a generalized indirect Fourier transformation technique and the effective hydration number evaluated from the negative excess bulk water relaxation amplitude revealed by DRS unambiguously demonstrate that hydration water molecules, exhibiting about 4-times-slower collective reorientational dynamics than that of bulk water, contribute to the excluded volume of the micelles. The blocked terminal hydrogen-bond donor/acceptor site of MEE leads to smaller hydration number of MEE than compared to that of AE, and consequently the lower excluded volume of the MEE micelles. The effective micellar volume fraction, ϕeff, should be defined by incorporating such different hydration effects. Importantly, voluminosity, defined as the micellar volume fraction per unit mass, is clearly a decreasing function of w, demonstrating progressive dehydration at a higher w. The collective diffusion constants determined by DLS for the AE and MEE micelles show a monotonous increase up to ϕeff ≈ 0.5, as expected for the hard spheres. Low-shear-rate viscosities follow a Krieger-Dougherty model in the identical micellar packing fraction range. All static, dynamic, and mechanical properties of these micellar solutions can be explained in a consistent and quantitative manner only when the excluded volume of hydration water molecules is properly taken into account. [ABSTRACT FROM AUTHOR]

Abstract: The characterization of alcohol-ethoxylate substances is a significant challenge in analytical science. Their importance in industry and society makes it necessary to have methods for their rapid, reliable characterization and quantification. This overview highlights the instrumental separation techniques for their analysis – chromatographic (e.g., gas, liquid and supercritical fluid chromatography) and electrophoretic (e.g., capillary, gel, capillary zone, and non-aqueous capillary electrophoresis and micellar electrokinetic chromatography). We summarize and explain analytical parameters for their characterization. We include selected references and examples to show the appropriateness of instrumental separation techniques for the analytical characterization of alcohol-ethoxylate substances. [Copyright &y& Elsevier]

Surface tension measurements were carried out for systems containing binary mixtures of ethoxylated tert-octylphenols (with an average of 10 or 16 ethylene oxide groups-HC8PEO10 and HC8PEO16, respectively) with perfluorinated n-alcohol ethoxylates (fluoropentanol with an average of 10 ethylene oxide groups FC5EO10, and fluorohexanol with an average of 14 ethylene oxide groups FC6EO14). The obtained results and calculations indicate that fluorinated surfactants have the better efficiency and effectiveness in the reduction of surface tension of water that the hydrocarbonated alkyl phenol ethoxylates and that their mole fraction in the mixed monolayer at water-air interface for mixtures containing a 0.2 molar fraction of fluorinated surfactants in bulk phase is considerable higher than in the bulk phase. At concentrations of mixtures corresponding to saturated monolayer at water-air interface there is a synergetic effect in the reduction of $$ \gamma_{\rm LV} $$ for a mixture of HC8PEO16 + FC5EO10 at a 0.2 molar fraction of HC8PEO16; however, taking into account the lowest value of the molecular interaction parameter for mixed micelles calculated on the basis of Rosen approach, the result is that the best synergism takes place for mixture of HC8PEO16 + FC6EO14 at a 0.2 molar fraction of HC8PEO16. Moreover, the ability of the mixed monolayer formation relative to the mixed micelle formation varies with the concentration and composition of the studied mixtures. Graphical Abstract: The comparison between values of the free energy at water-air interface ( $$ \Updelta G_{\min }^{\rm S} $$) and the standard Gibbs energy of micellization, $$ \Updelta G_{\rm mic}^{0} $$, for aqueous solutions of hydrocarbon (HC8PEO10, HC8PEO16) and fluorinated (FC6EO14, FC5EO10) surfactants and their two binary mixtures.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Mineral surfaces form the main sorption phase for alcohol ethoxylates (AEs) in marine sediment. Competition for adsorption sites is investigated for marine sediment and kaolinite clay using simple mixtures of AE homologues. For both sorbents, adsorption sites on mineral surfaces can be effectively blocked by an AE homologue with the strongest adsorption affinity. The strongly adsorbed AE, however, forms a second sorption phase to which weakly adsorbing AE will sorb, forming bilayers. An extended dual-mode model accounts for competition effects, while still based on sorption properties of individual compounds. Competition effects become apparent when total adsorbed concentrations reach ∼10% of the adsorption capacity. Deviations from individual sorption isotherms depend on affinity constants and dissolved homologue composition. Competition will not often occur in contaminated field sediments, with AEs concentrations usually far below the adsorption capacity, but will affect sorption studies, sediment toxicity tests or applications with nonionic surfactant mixtures. [Copyright &y& Elsevier]

A study of adsorption/recovery of nonylphenol 9 mole ethoxylate (NP9EO) on a crosslinked β-cyclodextrin-carboxymethylcellulose (β-CD-CMC) polymer was carried out by ultraviolet-visible (UV-vis) and Fourier transform infrared (FTIR) spectroscopies. The adsorption was performed in mixtures containing 500mg of the β-CD-CMC polymer and aqueous NP9EO solutions at concentrations 12-82 mg/L, whereas the recovery of NP9EO was effectuated by shaking the β-CD-CMC polymer loaded with methanol. The assays were made at 25°C and atmospheric pressure under agitation. The results have shown that the adsorption is a rapid process and the β-CD-CMC polymer exhibits a high NP9EO adsorption capacity of 83-92w% (1.1-6.8mgNP9EO/g β-CD-CMC polymer) dependent of the initial NP9EO concentration in liquid phase. This adsorption may involve the formation of an inclusion complex β-CD-NP9EO and a physical adsorption in the polymer network. The adsorption equilibrium measurements, which were analyzed using the Langmuir isotherm, have indicated a monolayer coverage and the homogeneous distribution of active sites at the surface of the β-CD-CMC polymer. Moreover, the negative value obtained for the free energy change (213.2 kJ/mol) has indicated that the adsorption process is spontaneous. In parallel, the β-CD-CMC polymer exhibited a high NP9EO recovery efficiency of 97w% that may occur through a decrease of binding strength between β-CD-CMC polymer and NP9EO. Together, these results suggest that the β-CD-CMC polymer could constitute a good adsorbent for removing nonylphenol ethoxylates from wastewater due to its high adsorption capacity and non-toxic character of β-CD and CMC to environment. [ABSTRACT FROM AUTHOR]

Aqueous solutions of ethoxylated alcohols which form lyotropic liquid crystals at high concentrations (40-80%) were selected as model lubricating substances. Microscopic studies under polarized light and viscosity measurements were carried out in order to confirm the presence of liquid crystalline structures in the case of alcohol solutions with ethoxylation degrees of 3, 5, 7 and 10. Microscopic images and viscosity coefficient values characteristic of various mesophases were obtained. As expected, the viscosity of LLCs decreases considerably with an increase in shearing rate which is characteristic of liquid crystals being non-Newtonian liquids. Antiseizure properties were determined by means of a four-ball machine (T-02 Tester) and characterized by scuffing load (Pt), seizure load (Poz) and limiting pressure of seizure (poz). Alcohol ethoxylates forming mesophases in aqueous solutions have the strongest effect on the Pt values which are several times higher than those measured in the presence of water. Ethoxylates with higher degrees of ethoxylation exhibit higher values of scuffing load. Those changes have been interpreted as a result of higher cloud points at which those compounds lose their amphiphilic properties. In general, the presence of mesophases in the bulk phase and particularly in the surface phase may lead to the formation of a lubricant film which separates the frictionally cooperating elements of a friction pair. The antiseizure efficiency of alcohol solutions is highest up to the load value which does not exceed the scuffing load value. [ABSTRACT FROM AUTHOR]

Abstract: Recent regulatory pressures (e.g., REACh, CEPA) requiring bioaccumulation assessments and the need for reduced animal use have increased the necessity for the development of in vitro-based methods to estimate bioaccumulation. Our study explored the potential use of subcellular and cellular hepatic systems to determine the biotransformation potential of two surfactants: octaethylene glycol monohexadecyl ether (C16EO8) and diethylene glycol monotetradecyl ether sulfate (C14EO2S). The subcellular systems tested were liver homogenates and microsomes from the common carp (Cyprinus carpio) and rainbow trout (Oncorhynchus mykiss). Cellular systems consisted of primary hepatocytes from the common carp (C. carpio) and PLHC-1 cells, hepatocarcinoma cells from the desert topminnow (Poeciliopsis lucida) cell line. Each in vitro system was exposed to radiolabeled test compounds and assayed for biotransformation using liquid scintillation and thin layer chromatographic methods. First-order kinetics were used to estimate rates of biotransformation. Bioconcentration of test materials in fish were predicted using an in vitro to in vivo metabolic rate extrapolation model linked to a mass-balance model commonly used to predict bioaccumulation in fish. Both subcellular and cellular tests using microsomes, liver homogenates and hepatocytes respectively showed biotransformation of the parent surfactants. Biotransformation rates were fastest for hepatocytes, followed by microsomes and homogenates. Rates were too low from homogenate tests to extrapolate to in vivo-based biotransformation rates using the extrapolation model. Trout microsomes metabolized C16EO8 faster than carp microsomes, yet rates were approximately the same for C14EO2S. Predicted BCF values incorporating in vitro biotransformation rates from hepatocytes were similar to measured in vivo or USEPA’s bioconcentration model (BCFWIN) predicted values. Predicted BCF values using microsomal-based rates from trout and carp studies were only slightly less than default BCF values which assumes a linear logKow to BCF relationship with no biotransformation. However, hepatocyte-based results showed substantially decreased BCFs compared to the default BCF values. These results indicate that BCF estimates based on in vitro metabolic rates can provide reasonable estimates of in vivo BCF values, therefore, supporting the use of in vitro approaches within a tiered approach to assess bioconcentration. [Copyright &y& Elsevier]

Palm-based lauryl alcohol ethoxylates were synthesized with different chain lengths of ethylene oxide using an ethoxylation reactor. The effect of changing the ethylene oxide chain length was investigated by reacting 3, 6 and 100 moles of ethylene oxide with palm- based lauryl alcohol. The samples were labeled as C12E3, C12E6 and C12E100. The 6 moles of ethylene oxide was approximately the same length as the palm-based lauryl alcohol. The chromatograms of C12Ex showed less retention peaks than the standard, Brij 40 (Tetraethylene glycol dodecyl ether - C12E4). Fourier Transformed Infrared Spectroscopy (FTIR) displayed a strong C-O stretch at 1120 cm-1 which was attributed to C-O single-bond stretching of the ether group. The ternary phase diagrams for a series of olive or olein oil/water/C12Ex systems were investigated at 25°C. The important features of the ternary phase systems are the emulsion and the concentrated emulsion phases. Optical microscopy revealed the difference in morphology between emulsion and concentrated emulsion. The particle size of the emulsions and the concentrated emulsions were in the range of 2.635 μm to 9.175 μm and 0.694 μm to 4.764 μm, respectively. The rheological flow curves measurement of the concentrated emulsion showed crossover of the ascendant and descendant curves which indicated structural build up of the sample instead of destruction. [ABSTRACT FROM AUTHOR]

Several analytical methods have been developed for analyzing alcohol ethoxylates (AE) in aqueous environmental samples. These methods differ widely in their selectivity and sensitivity for measuring the AE components; that is, they vary in their resolution of alkyl chain length homologs and ethoxymer distributions (degree of ethoxylation for each homolog). Given these differences, AE monitoring results from different studies often are inconsistent and, sometimes, are deemed to be incomparable. To address these differences, three currently available methods for determining AE concentrations in environmental matrices were compared among a common set of wastewater treatment plant samples. These methods included the detection of hydrogen bromide--derivatized homologs by gas chromatography/mass spectrometry, the detection of aqueous homologs by high-pressure liquid chromatography/electrospray mass spectrometry, and the detection of pyridinium-derivatized homologs by high-pressure liquid chromatography/electrospray mass spectrometry. Results from the present study showed that all three methods responded differently in determining the complex suite of chemical species that comprise AE in the environment. The collective information, however, allowed a consistent comparison among the methods. This comparison was then used to reevaluate results from previous AE monitoring studies. Results from this reevaluation provided a more realistic profile of both historical AE removal during wastewater treatment as well as the occurrence of AE in U.S. surface waters. [ABSTRACT FROM AUTHOR]

Supercritical fluid chromatography (SFC) was used for the analysis of ethoxylated and propoxylated surfactants. Samples were derivatized to phenylated silyl ethers with a disilazane–chlorosilane mixture. Addition of a phenyl group to the surfactant allowed UV-absorbance detection of each oligomer. Acetonitrile and methanol were evaluated as mobile phase modifiers. Better peak shape was realized with methanol-modified CO2 on an octadecyl silica bonded phase than with acetonitrile-modified CO2. Peak assignments were made via SFC coupled with electrospray ionization–mass spectrometry (ESI–MS) in the positive ion mode. A sulfonamide-embedded alkyl stationary phase was also evaluated for separation of the derivatized samples. SFC–UV and SFC–ESI–MS data were jointly used for calculation of average molar oligomer values which were then compared to values calculated from 1H NMR data of non-derivatized samples. The derivatization or separation method using the sulfonamide embedded phase required no preliminary cleanup and yielded reproducible oligomer values that were consistent with those of the manufacturer’s nominal values. [Copyright &y& Elsevier]

The retention behaviour of fatty alcohol ethoxylates and fatty acid methyl ester ethoxylates on various reversed-phase columns in acetone–water has been studied in the regime of liquid exclusion–adsorption chromatography at different temperatures. Straight lines were obtained in the van’t Hoff plots. The entropy and enthalpy changes were found to be negative (at least in the range of lower oligomers) and showed a dependence of the number of oxyethylene units. For higher oligomers, both entropy and enthalpy changes approach a constant value. This can be explained by the existence of a rather thick layer of organic solvent close to the surface of the stationary phase. [Copyright &y& Elsevier]

The responses of fish, invertebrates, and periphyton during a 56-day exposure to a C12–15 linear alcohol ethoxylate surfactant were studied in stream mesocosms. An individual stream consisted of a slow-flowing pool section and a faster-flowing riffle section. The surfactant has an average distribution of nine ethoxylate groups per mole of alcohol. Eight stream mesocosms were used to test the effects of seven concentrations of the surfactant. Time-averaged, mean, measured concentrations were 20, 40, 70, 160, 300, 390, and 740 μg/L, which represented 70–100% of nominal concentrations. The exposure of aquatic communities to the C12–15AE-9 surfactant in stream mesocosms resulted in no-observed-effect concentrations (NOECs) for individual endpoints ranging from 160 to 740 μg/L. Among the more sensitive responses were Oncorhynchus mykiss time to swim up and fry growth, abundance of juvenile Gammarus pulex in drift samples, Baetis abundance in the riffle sediment and in samples collected from tiles placed in the riffle, and Simulium density in the riffle tiles, all with NOECs of 160 μg/L. Responses of the riffle sediment invertebrate assemblages assessed using multivariate methods support a NOEC of 160 μg/L. Abundances of G. pulex, Copepoda, and Agapetus sampled in the pools and pool tiles were not affected at the highest surfactant concentration tested after 56 days. Surfactant effects on periphyton and community leaf processing were seen at 300–390 μg/L. Based upon the responses of several taxa representing different trophic levels, a mesocosm NOEC of 160 μg/L can be stated for the C12–15AE-9 surfactant. This study provided additional data that can be used to reduce the uncertainty in extrapolating laboratory data to the field for the environmental risk assessment of alcohol ethoxylates. [Copyright &y& Elsevier]

Fatty alcohol ethoxylates (FAEs) are widely used nonionic surfactants that have distributions in both alkyl and poly(ethylene oxide) (PEO) chain length. Generally, two-dimensional liquid chromatography technique is required for the complete characterization of both distributions. By selecting a proper stationary and mobile phase condition, however, we can obtain fully resolved chromatograms of a FAE sample (Brij 30) with respect to both alkyl and PEO chain length by using a single reversed-phase C18 column and aqueous acetonitrile mobile phase. FAEs show a peculiar reversed-phase liquid chromatography (RPLC) retention behavior with an aqueous–organic mobile phase, the retention mechanism of which has not been fully elucidated. For a fixed alkyl chain length, FAEs with higher-molecular-mass PEO block elutes first and the van’t Hoff plot of the retention factor shows a curvature. The unique retention behavior can be understood from the opposite thermodynamic characteristics associated with RPLC retention of PEO block and alkyl chain: the sorption process of PEO to the non-polar stationary phase shows ΔHo>0 and ΔSo>0 while the alkyl chain shows ΔHo<0 and ΔSo<0 in contrast. The relative magnitude of the two contributions can change the elution order of the FAE. Therefore the often found, inverted elution order of FAEs (the early elution of FAEs with longer PEO block) is due to the positive enthalpic interaction of PEO blocks, which is a characteristic of the hydrophobic interaction. And the curvature of the van’t Hoff plots was analyzed assuming the temperature dependent thermodynamic variables. [Copyright &y& Elsevier]

Alcohol ethoxylates (AEs) and alkylamine ethoxylates (AMEs) are used as adjuvants in pesticide formulations. Analytical procedures for these compounds in environmental aqueous samples using LC–MS are presented. Sample preparation uses solid-phase extraction with Porapak Rdx cartridges. Detection limits and recoveries in ground water and surface water are, respectively, AEs: 16–60 ng/l, 35–93% and AMEs: 0.3–6 μg/l, 28–96%. The lower recoveries are obtained for the apolar surfactants. The procedure was employed on samples of ground water and soil interstitial water collected from farming areas. The individual AEs were detected at concentration levels ranging from 33 to 189 ng/l water. [Copyright &y& Elsevier]

Fatty alcohol ethoxylates can be analyzed using a combination of liquid chromatography under critical conditions as the first dimension and liquid exclusion–adsorption chromatography as the second dimension. Transfer of fractions from the first to the second dimension is achieved using the full adsorption–desorption (FAD) technique. The peaks of interest in the first dimension are trapped on a short precolumn before injecting them into the second dimension. Full adsorption is achieved by increasing the water content in the mobile phase before the FAD column. When the fractions are desorbed by switching to the mobile phase of the second dimension, they are focused and reconcentrated. In this way, a full resolution of oligomers is achieved. As both dimensions are run in isocratic mode, density and refractive index detection can be applied, which allows an accurate quantitation. [Copyright &y& Elsevier]

Biodegradation of the two largest classes of nonionic surfactants—alcohol ethoxylates and nonylphenol ethoxylates—has been studied under realistic summer and winter weather conditions. Data obtained using double-radiolabeied surfactants provided a greater understanding of the mechanisms by which the surfactants biodegrade. The study shows that alcohol ethoxylates degrade to CO2 and H3O faster and more extensively than nonylphenol ethoxylates under both summer and winter conditions in addition, sewage effluents contained greater quantities of biodegradation intermediates from nonylphenol ethoxylates than from alcohol ethoxylates. Under northern U.S. winter conditions, the biodegradation of nonylphenol ethoxylates was particularly poor, and resulted in effluents having considerable foaming. In contrast, biodegradation of alcohol ethoxylates under the same winter conditions did not result in effluent foaming. [ABSTRACT FROM AUTHOR]