Evaluation of selected‐ion flow‐tube mass spectrometry for the measurement of ethanol,methanol and isopropanol in physiological fluids: effect of osmolality and sample volume

Selected‐ion flow‐tube mass spectrometry (SIFT‐MS) is particularly suited for the analysis of volatile low molecular weight compounds. We have evaluated this technique for the assay of different alcohols in aqueous solutions, including blood plasma, and in particular whether the osmolality or sample volume affected vapourisation. Solutions of three different alcohols (methanol, ethanol and isopropanol) ranging from 0.005 to 50 mmol/L were prepared in deionised water (0 milliosmol), phosphate‐buffered saline (690 mOsm), isotonic saline (294 mOsm) and plasma (296 mOsm). The vapour above the sample (50 to 1000 µL) contained in air‐tight tubes at 37°C was aspirated into the instrument. The outputs for ethanol, methanol and isopropanol were linear over the concentration range and independent of the sample volume and relatively independent of the osmolar concentration. SIFT‐MS can reliably and accurately measure common alcohols in the headspace above aqueous solutions, including serum/plasma. This novel application of SIFT‐MS is easy to follow, requires no sample preparation and the wide dynamic range will facilitate measurement of alcohols present from normal metabolism as well as when taken in excess or in accidental poisoning. Copyright © 2009 John Wiley & Sons, Ltd.     

Ethanol loading in an inductively coupled plasma

Changes to the fundamental and analytical parameters of a plasma have been investigated when ethanol has been added to aqueous or organic solutions. Excitation temperature, electron number density, and intensity of the H(alpha) line increased when ethanol has been added to aqueous solutions, while an electron density decrease and signal reduction have been found when ethanol has been added to xylene. The sensitivity has been improved for all ethanol concentrations when water has been the solvent, but the reverse has been found for xylene solutions.     

Purification of secoisolariciresinol diglucoside with column chromatography on a sephadex LH-20

A simplified and efficient method is developed for the large-scale purification of the secoisolariciresinol diglucoside (SDG) from defatted flaxseed after aqueous ethanol extraction. Extractant from defatted flaxseed with aqueous ethanol is hydrolyzed with basic solution, concentrated under vacuum, subjected to Sephadex LH-20 column chromatography, and eluted with aqueous ethanol of different concentrations. Elution is monitored by a UV detector at 280 nm, and fractions containing SDG are pooled, concentrated, and applied to a second column chromatography under the same conditions. Elution with water results in a better resolution of SDG [94.5% by high-performance liquid chromatography (HPLC)] than that with pure ethanol or 50% (v/v) aqueous ethanol. HPLC-photodiode array detection-mass spectrometry and NMR are applied to identify SDG and to determine the purity of the eluted fraction. This simplified purification scheme avoids toxic organic solvent used in the common silica gel separation process and, thus, increases the safety of the process.     

Enhancement of oral bioavailability of d-alpha-tocopherol acetate by lecithin-dispersed aqueous preparation containing medium-chain triglycerides in rats

In order to evaluate oral dosage forms of d-alpha-tocopherol acetate (VEA), d-alpha-tocopherol (VE) concentration in the plasma was examined following oral administration of three VEA preparations; lecithin-dispersed aqueous preparation, polysorbate 80 (PS-80)-solubilized aqueous solution and soybean oil solution. The lecithin-dispersed preparation gave the highest Cmax and the largest AUC0-24h, while Tmax was delayed. In the thoracic duct fistula rat, no increase in VE plasma concentration was observed after intraduodenal administration of lecithin-dispersed VEA preparation via the lymphatic route. The delayed Tmax and prolonged VE plasma concentration obtained with the lecithin-dispersed preparation in comparison with PS-80-solubilized aqueous solution could be explained by the different route of absorption.     

Effect of l-menthol on the permeation of indomethacin, mannitol and cortisone through excised hairless mouse skin.

The effect of l-menthol on the skin permeability of mannitol, cortisone or indomethacin was examined by an in vitro penetration technique with hairless mouse skin. The donor solution was prepared with phosphate buffered saline, ethanol:buffered saline (20:80, v/v) or ethanol:buffered saline (20:80, v/v) containing 1% (w/v) l-menthol. Although ethanol showed little enhancing effect, l-menthol in an aqueous ethanol vehicle at pH 7.4 increased the permeability coefficients of mannitol and indomethacin by about 100 times that of the control (an aqueous vehicle) and increased that of cortisone by about 10 times. l-Menthol, however, scarcely enhanced the penetration of indomethacin at pH 3.0, the majority of the species being in unionized form. These results suggested that the menthol-ethanol-aqueous system enhanced skin permeability through a direct effect on the polar and/or lipid pathways, while the thermodynamic activity of the penetrant molecule in the delivery vehicle might also influence the effectiveness of the penetration enhancer.     

Ethanol loading in an inductively coupled plasma

Changes to the fundamental and analytical parameters of a plasma have been investigated when ethanol has been added to aqueous or organic solutions. Excitation temperature, electron number density, and intensity of the H line increased when ethanol has been added to aqueous solutions, while an electron density decrease and signal reduction have been found when ethanol has been added to xylene. The sensitivity has been improved for all ethanol concentrations when water has been the solvent, but the reverse has been found for xylene solutions.     

Microstructure and electrical-optical properties of cesium tungsten oxides synthesized by solvothermal reaction followed by ammonia annealing

Cesium tungsten oxides (Cs_xWO₃) were synthesized by solvothermal reactions using ethanol and 57.1 vol% ethanol aqueous solution at 200 °C for 12 h, and the effects of post annealing in ammonia atmosphere on the microstructure and electrical-optical properties were investigated. Agglomerated particles consisting of disk-like nanoparticles and nanorods of Cs_xWO₃ were formed in the pure ethanol and ethanol aqueous solutions, respectively. The samples retained the original morphology and crystallinity after annealing in ammonia atmosphere up to 500 °C, while a small amount of nitrogen ion were incorporated in the lattice. The as-prepared Cs_xWO₃ sample showed excellent near infrared (NIR) light shielding ability as well as high transparency in the visible light region. The electrical resistivity of the pressed pellets of the powders prepared in pure ethanol and 57.1 vol% ethanol aqueous solution greatly decreased after ammonia annealing at 500 °C, i.e., from 734 to 31.5 and 231 to 3.58 Ω cm, respectively.     

SYNERGETIC EFFECT OF SUCROSE AND ETHANOL ON FORMATION OF TRIGLYCERIDE MICROEMULSIONS

The phase behavior of soybean oil, a nonionic surfactant (ethoxylated monodiglycerides) and an aqueous phase of water containing ethanol, and sucrose was investigated at 35 and 40°C. A minimum concentration of 20 wt% ethanol was required for the formation of isotropic solutions. Addition of sucrose to the aqueous phase decreased the amount of ethanol required to form these solutions. The solubilization mechanism of the oil was investigated by small angle x-ray diffraction and polarized light microscopy. A stable lamellar liquid crystalline phase was formed for a mixture of 75/25 surfactant/sucrose solution (2.5 wt% sucrose). This phase was destabilized with increased concentrations of sucrose and liquid crystalline phases having hexagonal structures were favored at 8.75 wt% sucrose. At a ratio of 55/45 wt% of surfactant/sucrose solution (9 wt% sucrose) hexagonal structures were formed and could be destabilized or destroyed by addition of ethanol. The concept of stabilization and destabilization of liquid crystalline mesophases was applied to the solubilization of triglycerides in aqueous solutions. Two microemulsion regions were identified; oil-in-water (L₁) and water-in-oil (L₂) in systems containing soybean oil, ethoxylated monodiglycerides, and 20 wt% ethanol solution. At 55/45 wt% surfactant/20 wt% ethanol solution,7.5 wt% of soybean oil was solubilized. Addition of 10, 20, and 30 wt% sucrose, at the same ratio of surfactant to ethanol solution, increased the solubility of the oil to 9, 13.5, and 18 wt% respectively. In addition, the size of the L₁ phase increased and moved to the aqueous corner of the phase diagram and the size of the L₂ phase decreased.     

微流动注射-等离子体质谱直接测定白酒中铅和镉

研制了多采样体积的微流控芯片, 结合普通的八通阀实现了等离子体质谱(ICP-MS)亚微升级样品的进样. 研究了白酒基体[52%(体积分数)乙醇]引入量对ICP的稳定性和裂解后所产生碳干扰的情况, 考察了进样体积与灵敏度的关系, 并优化了载流流速. 实验结果表明, 当进样量低于0.8 μL时, ICP-MS能长时间正常运行, 未出现积碳现象; 进一步将进样量降到0.3 μL以下, 可消除白酒基体中的碳所引入的质谱干扰. 在此基础上建立了用微流动注射ICP-MS直接测定白酒中Pb和Cd的方法, 每小时可分析45个样品, Pb和Cd的检出限分别为12和42 ng/L. 以水标准溶液直接测定了6个白酒样品中的Cd和Pb含量, 结果与微波消解-常规进样系统ICP-MS的分析结果一致.     

辉光放电低温等离子体分解乙醇水溶液制氢

在辉光放电分解乙醇制氢过程中, 高能电子在反应中起到了最为关键的作用, 非法拉第效应使得电流效率获得大幅度提升, 产物产量远远高于理论产量. 本文研究了乙醇水溶液辉光放电等离子体电解制氢的过程. 实验研究发现, 辉光放电分解乙醇水溶液的产物主要以H₂和CO为主, 还有少量的C₂H₄、CH₄、O₂和C₂H₆. H₂体积分数能达到59%以上, CO为20%左右. 通过对影响辉光放电的因素进行实验后发现: 乙醇体积分数的大小不会影响辉光放电的伏安特性参数; 电导率的提高会使‘Kellogg 区’收窄, 同时使放电尽快进入辉光放电. 此外, 乙醇体积分数越高H₂体积分数越低, 产气速率在乙醇体积分数为30%和80%附近时达到极大值; 提高放电电压和电导率对辉光放电的影响规律是相类似的, 其实质都是增大了辉光放电加载在等离子鞘层两端的电压,H₂体积分数基本不随二者的变化而变化, 但提高溶液的电导率更有利于减少辉光放电引起的焦耳热.     

Electrooxidation of ethanol on carbon nanotubes–nickel nanoparticles composites in alkaline media

In this report, the preparation of carbon nanotubes–Ni nanoparticles composites (CNT–Ni) is presented. The morphology and elemental composition of CNT–Ni composites were examined by transmission electron microscopy and X-ray diffraction. The electrochemical behaviour of carbon nanotubes–Ni nanoparticles composites in an aqueous solutions of alkali and alkaline solutions of ethanol has been studied by linear sweep voltammetry. The peak on the potentiodynamic curve for CNT–Ni composite electrode in alkaline solutions of ethanol is observed which is ascribed to the ethanol oxidation in alkaline medium. The results obtained are discussed from the point of view of employment of the CNT–Ni composites for the catalytic electrodes of fuel cells.     

Effect of d-limonene on the amounts of ethanol and indomethacin penetrated from aqueous gel ointments to rat skin.

The amounts of d-limonene, ethanol and indomethacin (IMC) which were transferred from aqueous gel ointments to the skin were determined in rats. The concentration of IMC in the skin correlated well with the plasma concentration of IMC percutaneously absorbed from the gel ointment. The increase of d-limonene concentration in the gel ointments was directly proportional to the accumulation of ethanol in the skin. The amount of ethanol in the skin was closely associated with the percutaneous absorption of IMC. As a possible mechanism for enhancement action of d-limonene and ethanol, it was considered that, at first, d-limonene penetrates into the skin under coexistence with ethanol and may change the barrier structure of the stratum corneum. The transfer of ethanol to the skin is thereby enhanced under the coexistence of d-limonene in the skin. Thus, the permeation of IMC can be promoted due to its affinity with ethanol.     

Evaluation of particle deposition in aqueous solutions by the quartz crystal microbalance method

Concerning the redeposition of particulate soils in the detergent process, particle deposition onto substrates in aqueous solutions was investigated by the application of the quartz crystal microbalance (QCM) technique, and the effects of the kinds of the particle and substrate and the addition of ethanol were discussed by the extended DLVO theory. The film of polyethylene, Nylon 6 or cellulose acetate as a substrate was prepared on the gold electrode of the QCM by a spin-coating method. The electrode with or without the polymer film was perpendicularly immersed in the aqueous dispersion of spherical polyethylene or nylon particles. The total mass of particles deposited onto the electrode was determined, in situ, from frequency change of the QCM. The deposited mass was also determined from the difference in frequency measured in air before and after the immersion in the dispersion. In both cases, the particle deposition increased with immersion time and attained apparent equilibrium after 30–60 min. Apparent equilibrium deposition was large for the polyethylene particle compared with the Nylon 12 particle. For either particle, a considerable difference in the deposited amount was observed among the substrates. In all systems, the particle deposition drastically decreased by addition of ethanol to the aqueous dispersion. The results were discussed in terms of the electrical double layer, the Lifshitz–van der Waals and acid–base interactions between the particle and the substrate, which were calculated using the experimentally determined surface free energy components and electrokinetic potentials.     

LC Separation of Co-Existing Cetylpyridinium Chloride, Tetradecyltrimethylammonium Bromide and Dodecyltrimethylammonium Bromide on Silica TLC Plates with Aqueous-Organic Eluents

Thin-layer chromatography (TLC) of three cationic surfactants was performed on silica TLC plates with various solvent systems. The mutual separation of cetylpyridinium chloride (CPC), tetradecyltrimethylammonium bromide (TTAB) and dodecyltrimethylammonium bromide (DTAB) was achieved on silica TLC plates with ethanol: 1% aqueous ammonium chloride (4:6, v/v) as an eluent. Effects of cations and anions in the mobile phase on mobility and separation of CPC, TTAB and DTAB were examined. The interference due to the presence of metal cations as impurities on the resolution in the mixture of CPC, TTAB and DTAB was also examined. The limits of detection of CPC, TTAB and DTAB estimated were 0.015, 0.031 and 0.062 μg zone⁻¹, respectively. The developed method was utilized to identify these surfactants in different spiked water samples after their preliminary separation.     

气相色谱法测定费托合成水相产物中的低碳醇、醛、酮化合物

建立了铁基催化剂费托合成反应水相产物中低碳(C₁~C₈)醇、醛、酮的气相色谱测定方法.对色谱分离条件进行了优化,确立了以乙醇为基准物质并结合各组分校正因子的定量方法;考察了方法的精密度和准确度,并对费托合成反应水相产物样品进行了测定.结果表明,乙醇在不同的含量范围内呈现良好的线性关系,相关系数均大于0.99.费托合成水相产物中的加标回收率在93.4%~109.6%之间,准确性可以满足实际分析的需要.实际费托合成水相产物的分析结果表明,费托合成水相产物中主要的低碳醇、醛、酮的总质量分数约为3%~12%,乙醇含量最高(约为1.7%~7.3%),且正构醇、异构醇和醛酮类化合物所占的总比率依次降低.该方法简单、快速,对费托合成水相产物中重要组分的分析有重要意义.     

Pulsed Electrical Discharges in Water: Can Non-volatile Compounds Diffuse into the Plasma Channel?

The objective of this research effort is to develop a more comprehensive understanding of how molecules get degraded in plasma during an electrical discharge in water. The study correlates the intensity of hydroxyl (OH) radicals in the plasma and physicochemical properties of aqueous solutions of methanol, ethanol, acetonitrile, acetone, dimethyl sulfoxide (DMSO), dimethyl formamide (DMF), phenol, hydroquinone, caffeine, and bisphenol A (BPA). To determine the tendency of the used compounds to penetrate the plasma, their vapor pressures, Henry’s constants, aqueous solubilities, reaction rate constants with OH radicals, and octanol–water partition coefficients are compared and correlated with plasma spectroscopic and hydrogen peroxide (H₂O₂) measurements. OH radicals are precursors to the formation of hydrogen peroxide and any compound that diffuses into the plasma will react with and lower the intensity of OH radicals and therefore the concentration of hydrogen peroxide in the bulk liquid. Optical emission spectroscopy (OES) reveals that all the used compounds diffuse inside the plasma channel regardless of their vapor pressure where they get oxidized (primarily by OH radicals) and thermally degraded. Results also indicate that hydrophobicity (i.e., octanol–water partition coefficient) is the most important property that determines a compound’s tendency to diffuse inside the plasma channel; hydrophobic compounds readily penetrate the plasma whereas hydrophilic compounds tend to stay in the bulk liquid. The rate of formation of hydrogen peroxide is independent of the type of the compound present in the bulk liquid which confirms that this molecule is formed at the plasma interface.     

Aqueous biphasic hydroformylation of higher alkenes and highly efficient catalyst recycling in the presence of a polar low boiling solvent

The hydroformylation of higher alkenes under aqueous biphasic reaction conditions with a rhodium catalyst derived from BISBIS (sodium salt of sulfonated 2,2′-bis (diphenylphosphinomethyl)-1,1′-biphenyl) in the presence of a polar low boiling point solvent was studied. The addition of ethanol greatly accelerated hydroformylation, such that the turnover frequency (defined as the moles of converted alkene per mole of Rh per hour) and the selectivity for linear aldehyde were up to 2095 h^?1 and 99 %, respectively. The catalytic system could be recycled for at least five runs without significant loss of activity in the aqueous biphasic hydroformylation of 1-octene; the rhodium content leaching in product mixtures detected by inductively coupled plasma atomic emission spectroscopy was < 0.1 ppm.     

Solubility of Succinic Acid in Ethanol Plus Water Systems from 278.15 K to 333.15 K

In an equilibrium vessel, the solubilities of succinic acid in binary aqueous ethanol solvents were measured by the analytical stirred-flask method with the temperature ranging from 278.15 to 333.15 K at atmospheric pressure. Data on the corresponding solid–liquid equilibrium of succinic acid in binary aqueous ethanol solutions are essential for industrial design and further theoretical studies. The effect of solvent composition and temperature on the solubility is discussed. The solubility data were correlated with the Combined Nearly Ideal Binary Solvent/Redlich-Kister (CNIBS/R-K) model. The solubility measured in this study can be used for succinic acid purification or optical resolution by the preferential crystallization procedure.     

Nanofiltration in non-aqueous solutions by porous silica–zirconia membranes

Porous membranes having various average pore sizes, ranging from 1 to 4 nm, were prepared from silica–zirconia composite colloidal sols by sol–gel processes, and were used for nanofiltration (NF) experiments in non-aqueous solutions of ethanol and methanol. Silica–zirconia membranes, which were tested in pure alcohol solutions for the first time after the preparation of the membrane, showed a gradual decrease in flux for approximately 100 h and then reached a steady flux. When the feed, after reaching the steady flux with ethanol, was changed to another alcohol, steady flux was attained after only several hours. Ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol (PEG) of various molecular weights (PEG400, 600, 1000, and 2000) were nanofiltrated in methanol and ethanol solutions at 50°C. Rejections in non-aqueous solutions increased with applied pressure, which is similar to aqueous solutions. Control of pore size of silica–zirconia membranes showing molecular weight cut-offs in methanol solutions at 300, 600, 1000, and >1000, respectively, was possible by the appropriate choice of colloidal particle sizes. Rejection in methanol solution showed a tendency similar to that in ethanol solution, while rejection in methanol was slightly larger than in ethanol solutions. In addition, rejection in water was much smaller than in methanol solution. For example, the rejection of PEG600 in water and methanol was 0.03 and 0.74, respectively. These results suggest that solvent type plays an important role in determining rejection, as a result of the interaction with solvents and/or membrane surface.     

High Efficient Extraction of Phthalates in Aquatic Products by a Modified QuEChERS Method

A simple, environmentally friendly and high efficient extraction method was proposed for the determination of five phthalates in aquatic products by gas chromatography combined with mass spectrometry detector (GC-MS). When this method was adopted, samples were pretreated by modified QuEChERS(quick, easy, cheap, effective, rugged and safe) method. An environmentally friendly extractant(ethanol aqueous solution) replaced toxic acetonitrile for extracting phthalates in the protein-matrix samples. Fluorescence quenching spectra of bovine serum albumin(BSA) with phthalates show that there was a high-affinity interaction between phthalate and protein, decreasing the extraction efficiency of phthalates from fish samples. However, in the 80%(volume fraction, φ) ethanol aqueous solution, a slow but full protein denaturation takes place, which would cause the unfolding of protein and the release of phthalates. Meanwhile, the fat-soluble impurities are extracted less in φ(ethanol) 80% aqueous solution than in either φ(ethanol) 100% or hydrophobic solvents in the liquid-liquid extraction procedure. Therefore the purification steps were greatly simplified. Overall recoveries were 81.77%―90.5% with limits of detection between 2.53 and 9.61 μg/L, and relative standard deviation values at 1.15%―4.85%. The proposed approach was satisfactorily applied to the determination of phthalates in real aquatic products, such as fish, shrimp and oyster.