Abstract  Fuel oxygenates are environmentally detrimental compounds due to their rapid migration to groundwater. Fuel oxygenates have been reported to cause taste and odour problems in drinking water, and they also have long-term health effects. Feasible analytical methods are required to observe the presence of fuel oxygenates in drinking and natural water. The authors studied ion mobility spectrometry (IMS) to determinate isomeric fuel ether oxygenates; ethyl tert-butyl ether (ETBE), diisopropyl ether (DIPE), and tert-amyl methyl ether (TAME), separated from aqueous matrices with a pervaporation membrane module. Methyl tert-butyl ether (MTBE) was also membrane extracted and detected with IMS. The authors demonstrated that fuel ethers (MTBE, ETBE, DIPE, and TAME) can be quantified at μg/L level with membrane extraction IMS. A membrane extraction module coupled to IMS is a time and cost effective analysis method because sampling can be performed in a single procedure and from different natural water matrices within a few minutes. Consequently, IMS combined with membrane extraction is suitable not only for waterworks and other online applications but also in the field monitoring the quality of drinking and natural water.

Abstract  A magnetic field enhanced photoelectron ionization (MEPEI) source combined with single photon ionization (SPI) for membrane inlet time-of-flight mass spectrometry was used for on-line detection of ether gasoline additive. Methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), methyl tert-amyl ether (TAME) and isopropyl ether (DIPE) were selected as the typical pollutants. A membrane inlet was used to transfer the analytes from liquid into gas phase in an on-line manner by pervaporization without sample pretreatment. Less sample fragments were in SPI, and molecular ions could be used to quick preliminarily qualitative analysis; high energy electrons and fragmentations produced by MEPEI can be used to accurate qualitative isomers and overcame the problem of resolution of overlapping peaks in complex matrix when using direct injection. Under the optimal conditions such as membrane temperature 60 degrees C, membrane thicknesses 50 mu m and membrane areas 160 cm(2), the single sample analysis time was less than 100 s, and the limits of detection for MTBE, ETBE, TAME and DIPE were 5.5, 4.8, 3.3 and 4.3 mu g/L, respectively. The instrument has been successfully applied to rapid analysis of MTBE in simulated water by gasoline.

Abstract  A rapid and relatively clean method for determining six organotin compounds (OtC) in textile goods with a gas chromatograph equipped with a conventional flame photometric detector (GC-FPD) has been developed. After the reflux-extraction to use methanol containing 1% (v/v) of hydrochloric acid, five hydrophobic OtC (e.g. tributyltin: TBT) and slightly less hydrophobic dibutyltin (DBT) could be drawn out through partitioning between the methanolic buffer solution and tert-butyl ethyl ether instead of hazardous dichloromethane, of which usage is provided by the official-methods notified in Japan, and following the ethylation procedure to use sodium tetraethylborate, the OtC were determined with the GC-FPD. The recoveries of DBT, TBT, tetrabutyltin, triphenyltin, dioctyltin, and trioctyltin from textile products (cloth diaper, socks, and undershirt) were 60-77, 89-98, 86-94, 71-78, 85-109, and 70-79% respectively, and their coefficients of variation were 2.5-16.5%. Calibration curves for OtC were linear (0.01-0.20 μg as Sn mL(-1)), and the correlation coefficients were 0.9922-1.0000. Their detection limits were estimated to be 2.7-9.7 n gas Sn g(-1). These data suggested that this method would be applicable to their simultaneous determination. Five retailed textile goods were analyzed by this proposed method, and 0.013-0.65 µg as Sn g(-1) of OtC (e.g. DBT) were determined in three. Moreover, a possibility that various OtC including non-targeted species in textile would be specifically detected by applying the studying speciation-technique of controlling signal intensity-flame fuel gas pressures of the GC-FPD was found.

Abstract  One factor hindering the economic feasibility of butanol fermentation is the energy intensity of the product separation. In this study a new approach for liquid-liquid extraction is presented. Gasoline additives were tested in conjunction with isooctane as extraction solvents, and a continuous process utilizing a novel, dual extraction is proposed. This method enables the usage of effective, nonbiocompatible solvents in ABE extraction without fear of inhibiting the microbes. The product mixture of this process could be utilized as a gasoline additive. No product purification steps are necessary, and very low energy consumption is achieved. The best extraction solvent was either MTBE or ETBE, depending on the operational parameters of the process.

Abstract  A case study of the green metrics analysis of several processes is described. The considered system is the simultaneous etherification of isobutene and isoamylenes with ethanol over Amberlys(TM) 35. Experimental results are compared under the green metrics methodology with those for the isolated ethyl tert-butyl ether and tert-amyl ethyl ether syntheses previously reported over acid ion-exchange resins using different reaction batch devices and different synthesis pathways, such as the production of both ethers from tertiary alcohols and from ethanol. The best results, from an environmental point of view, were obtained for ether syntheses from olefins and ethanol in terms of the parameters measured in the green metrics analysis. A process allowing the separation of ethers from the product stream and the reactants recirculation has been proposed and simulated. The suggested process depicts a suitable alternative for the simultaneous production of tertiary ethers from pure olefin feed and their downstream implementation as greener fuel additives with environmental benefits.

Abstract  The main objective of the following study was to determine the efficiency of a method that uses coconut charcoal as a solid-phase extraction (SPE) adsorbent in order to simultaneously detect six hydrophilic ether species in water in the low microgram-per-liter range. The applied method was validated for quantification of ethyl tert-butyl ether, 1,4-dioxane, ethylene glycol dimethyl ether (monoglyme), diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme) and tetraethylene glycol dimethyl ether (tetraglyme). SPE followed by gas chromatography/mass spectrometry of the extracts using the selected ion monitoring mode allowed for establishing low detection limits in the range of 0.007-0.018 μg/L in ultrapure water and 0.004-0.020 μg/L in environmental samples. Examination of the method accuracy and precision resulted in a recovery greater than 86.8 % for each compound with a relative standard deviation of less than 6.6 %. A stability study established a 5-day holding time for the unpreserved water samples and extracts. Finally, 27 samples obtained from surface water bodies in Germany were analyzed for the six hydrophilic ethers. Each analyte was detected in at least eight samples at concentrations reaching 2.0 μg/L. The results of this study emphasize the advantage of the method to simultaneously determine six hydrophilic ether compounds. The outcome of the surface water analyses augments a concern about their frequent and significant presence in surface water bodies in Germany.

Abstract  An in-source, stretched, hollow fiber membrane (HFM) inlet has been developed to improve the sensitivity of on-line time-of-flight mass spectrometry (TOFMS) with a vacuum ultraviolet (VUV) lamp based single photon ionization (SPI) source for the direct analysis of liquid samples. A 2-cm HFM was stretched to 8 cm in length, and placed in the ion source and directly under the VUV lamp window with a distance of 15 mm. Compared with the conventional flow-through configuration under the same experimental conditions, the signal intensities of selected volatile organic compounds (VOCs) of methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), benzene, toluene and p-xylene were increased over 5-fold in magnitude, and the response time was shortened to one-third. The limits of detection (LOD) of MTBE, ETBE, benzene, toluene and p-xylene ranged from 0.25 to 1.3 μg L(-1) with a measurement time of 60 s, and three orders of linear range were obtained with correlation coefficients of 0.9972-0.9992. The present results suggest that the in-source stretched HFM is a simple and effective way to increase the sensitivity and shorten response time of the membrane inlet, and we believe that it will also be beneficial to other types of on-line mass spectrometer for the on-line analysis of VOCs in water with a VUV lamp based SPI ion source.

Abstract  Analysis of volatile organic compounds (VOCs) provides an elegant approach for cancer screening and disease monitoring, whose use is currently limited by a lack of validated cancer-derived metabolites, which may serve as biomarkers. The aim of the experiments presented here was to investigate the release and consumption of VOCs from the non small cell lung cancer cell line NCI-H1666, which was originally derived from a bronchoalveolar carcinoma.Following detachment by trypsinization suspended cells were incubated in a sealed fermenter for 21 hours. 200 ml of headspace from the cell culture were sampled, diluted with dry, highly purified air and preconcentrated by adsorption on three different solid sorbents with increasing adsorption strength. VOC-analysis was performed by thermodesorption-gas chromatography mass spectrometry (TD-GC-MS). In contrast to our previous studies experiments with NCI-H1666 cells only confirmed the consumption of several aldehydes, n-butyl acetate and the ethers methyl tert-butyl ether and ethyl tert-butyl ether, but no unequivocal release of VOCs was observed. Together with our previously published work these data indicate that the consumption of certain VOCs is commonly observed while their release shows cell line-restricted patterns, whose underlying causes are unknown.

Abstract  Exposure to organic vapors in the workplace is a source of occupational risk. Admissible exposure levels are tightly regulated and must be closely monitored. However, the complexity and slowness of the existing complete protocols to determine diffusive uptake rates through passive sampling have limited the use of this tool despite obvious advantages. In this study, we experimentally validate two simplified protocols to determine diffusive uptake rates with passive sampling. The proposed 2(6-3) and 2(6-2) fractional factorial designs were validated for toluene sampling using a (Gas Adsorbent Badge for Individual Exposure) GABIE-activated charcoal sampler in a controlled atmosphere. The uptake rate for this sampler had been determined previously using a full protocol. The uptake rates for all three protocols were similar, indicating that the proposed new designs can be substituted for classical full protocols. After validation of our protocols, uptake rates for new substances used as fuel additives (methyl and ethyl tert-butyl ethers, MTBE and ETBE) were determined on the same sampler using the 2(6-2) design. In these experiments, temperature appears to have a non-negligible influence on the uptake rates measured for these compounds. With some precautions of usage (ambient temperature below a determined limit temperature or at least exposure time ≥4 h) and storage (storage temperature = 4°C) of the sampler, the experimental diffusive uptake rates determined by this method can be used with good confidence. Field experiments confirmed the experimental results, showing good agreement between active and passive sampling using the experimentally determined uptake rates.

Abstract  The aim of this study was to confirm the existence of volatile organic compounds (VOC) specifically released or consumed by the lung cancer cell line A549, which could be used in future screens as biomarkers for the early detection of lung cancer. For comparison, primary human bronchial epithelial cells (HBEpC) and human fibroblasts (hFB) were included. VOCs were detected in the headspace of cell cultures or medium controls following adsorption on solid sorbents, thermodesorption, and analysis by gas chromatography mass spectrometry. Using this approach, we identified VOCs that behaved similarly in normal and transformed cells. Thus, concentrations of 2-pentanone and 2,4-dimethyl-1-heptene were found to increase in the headspace of A549, HBEpC, and hFB cell cultures. In addition, the ethers methyl tert-butyl ether and ethyl tert-butyl ether could be detected at elevated levels in the case of A549 cells and one of the untransformed cell lines. However, especially branched hydrocarbons and alcohols were seen increased more frequently in untransformed than A549 cells. A big variety of predominantly aldehydes and the ester n-butyl acetate were found at decreased concentrations in the headspace of all cell lines tested compared with medium controls. Again, more different aldehydes were found to be decreased in hFB and HBEpC cells compared with A549 cells and 2-butenal was metabolized exclusively by both control cell lines. These data suggest that certain groups of VOCs may be preferentially associated with the transformed phenotype.

Abstract  The effect of interactions between organic solvents and water on the interfacial and bulk properties of N-ethyl-N-methylmorpholinium dicyanamide, [EMMor][DCA] were discussed on the base of the limiting activity coefficients gamma(infinity)(13) values. The experimental gamma(infinity)(13) values were determined by gas-liquid chromatography at temperatures from (298.15 to 368.15) K for 61 assorted solutes-among them, alkanes (linear, branched, or cyclic), alkenes, alkynes, aromatic hydrocarbons, alcohols, water, thiophene, tetrahydrofuran, 1,4-dioxane, ethers, acetone, ketones, acetonitrile, pyridine, and 1-nitropropane. The partial molar excess Gibbs free energy Delta G(1)(E,infinity), the partial molar excess enthalpy Delta G(1)(E,infinity), and entropy at reference temperature T-ref Delta S-1(E,infinity) at infinite dilution were calculated from the experimental gamma(infinity)(13) values obtained over this temperature range. The gas-liquid partition coefficient K-L was calculated for each solute and discussed in light of the Abraham solvation parameter model. The density and viscosity of the [EMMor][DCA] as a function of temperature were also measured. The selectivity and capacity for six separation problems were calculated from gamma(infinity)(13) and compared to literature values for selected ionic liquids. These separation problems are central to the petroleum and organic chemistry industry. The data presented here shows that [EMMor][DCA] reveals large selectivity equal 140, 273, 538, 73.1, 87.5 and 10.2 in heptane/benzene, heptane/thiophene, heptane/ethanol, hexane/ethyl acetate, ethyl-tert-butyl ether, ETBE/ethanol and THF/water separation problems at T = 328.15 K. The capacities were 0.22, 0.42, 0.83, 0.17 and 2.97 for benzene, thiophene, ethanol, ethyl acetate, and water at the same temperature. (C) 2018 Elsevier Ltd.

Abstract  Membranes made from cellulose acetate grafted with imidazolium or ammonium ionic liquids (ILs) containing different anions were considered for ethyl tert-butyl ether biofuel purification by pervaporation. The new cellulosic materials were obtained after bromide (Br-) exchange by different anions (Tf2N-, BF4-, AcO-). IL structure-membrane property relationships revealed that the membrane properties were strongly improved by varying the anion structure, molecular size and hydrogen bonding acceptor ability β in the Kamlet-Taft polarity scale. The grafted ammonium IL with AcO- anion combined the highest parameter β with big cation/anion sizes and finally led to the best membrane properties with a normalized pervaporation flux of 0.41 kg/h m2 (almost 20 times that of virgin cellulose acetate) for a reference thickness of 5 μm and a permeate ethanol content of 100%. Such properties thus corresponded to an outstanding separation factor at 50 °C.

Abstract  As ethanol and rapeseed oil are not miscible, tributyl citrate, 2,5-dimethylfuran (DMF), 2-methylfuran (2-MF), 2-methyltetrahydrofuran (2-MTHF), methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), rapeseed oil FAME-biodiesel (FAME), 1-heptanol (HepOH) and 2-ethylhexyl nitrate (EHN) are used as green mixing agents or "ethanolotropes". The area of existence of clear and monophasic mixtures as well as biphasic liquid/liquid solutions, determined in a previous work, are reported at 25 degrees C using ternary phase diagrams. In the present work, some of these ternary diagrams are completed by investigating their critical points (CPs). Further, the kinematic viscosity (kV) of different binary and ternary, clear and monophasic mixtures is measured at 25 and 40 degrees C and their phase behaviour is studied at 0, -15 and -20 degrees C. Dynamic light scattering (DLS) experiments are performed on various samples at 25 degrees C and the results are discussed with respect to previous measurements including DLS, static light scattering (SLS), small and wide angle X-ray scattering (SWAXS) and conductivity. Close to the CP of the investigated systems, the highest scattering intensities (SIs) can be observed as well as a distinct increase of the slope of the kV versus the rapeseed oil concentration. Evaluating these results, the high viscosities can be associated with the formation of a rapeseed oil continuum. Further, the monophasic domain close to the CP can be considered as bicontinuous-like. For every used "ethanolotrope", the mixtures meet the required ASTM D6751 standard for the kV of biodiesel. Thus, rules for possible adjustments to reach this standard by varying the nature and the quantities of the "ethanolotropes" are proposed. Ternary and binary melts with high amounts of rapeseed oil can meet the kV standard and are clear and monophasic below 0 degrees C or even below -15 degrees C. Binary mixtures of DMF or 2-MF with high amounts of rapeseed oil (70 wt%) show no phase transitions during several hours at -20 degrees C and form reversible, monophasic and clear gels. As the kV of these two binary mixtures is slightly above 6 mm(2)/s at 40 degrees C, they nearly meet the kV standard. Replacing ethanol by "ethanolotropes" like 2-MTHF or HepOH can lead to an increase of the monophasic region of these ternary mixtures at low temperatures. Moreover, this temperature dependence could be associated with the nanostructuring, since mixtures located in the bicontinuous-like regions seem to be more sensitive regarding their phase behaviour. (C) 2016 Elsevier Ltd. All rights reserved.

Abstract  Widespread use of fuel oxygenates, coupled with their high water solubility and slow degradation rate, have led to an increase in the potential for human exposure. We developed an accurate, precise, sensitive, and high-throughput analytical method to simultaneously quantify trace levels (low parts-per-trillion) of four fuel oxygenates in human blood: methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), di-isopropyl ether (DIPE), and tert-amyl methyl ether (TAME). The analytes were extracted from the head space above human blood samples, using solid-phase microextraction, desorbed into the heated injector, and chromatographically resolved by capillary gas chromatography. Analytes were detected by high-resolution mass spectrometry with multiple ion monitoring, and quantified against known standard levels by use of stable isotope-labeled internal standards for recovery correction. The low limits of detection (0.6 ng/L) allowed for measurement of MTBE, ETBE, DIPE, and TAME in parts-per-trillion levels with excellent precision (coefficient of variation ranging from 1.7 to 5.4%) and accuracy (96-100%). This method provides a means to assess fuel oxygenate exposure and study the potential relationship between exposure and adverse health outcomes.