Application of sucrose fatty acid ester to reverse micellar extraction of lysozyme

Reverse micellar extraction of lysozyme has been carried out using an organic solution containing a mixture of monoester and polyester of sucrose fatty acid ester. The forward extraction of lysozyme from the feed aqueous phase to the reverse micellar organic phase of the mixture of monoester and polyester of sucrose fatty acid ester at pH 7.2 was strongly dependent upon the weight fraction of monoester, while any amount of lysozyme was not extracted only by using monoester or polyester. The forward extraction ratio dramatically increased with an increase in the concentration of fatty acid ester, and was high around neutral pH and at low ionic strength. The backward extraction of lysozyme from the reverse micellar organic phase to the recovery aqueous phase exhibited high efficiency at acidic pH value or at high ionic strength. The addition of sucrose into the recovery aqueous phase promoted the backward extraction ratio, and caused the activity of lysozyme recovered from the reverse micellar phase to be retained perfectly.     

以葡萄糖为极性头基的表面活性剂的合成及苯基酮在手性胶束中的不对称还原

合成了三种长链烷基葡萄糖苷即1-O-十二烷基-β-D-葡萄糖(β-DG)、1-O-十二烷基-α-D-葡萄糖(α-DG)以及1-O-十二烷基-β-D葡萄糖醛酸钠(Sβ-DGU)、三种化合物在水中均能形成胶束, 在上述胶束中, 用硼氢化钠对一系列苯基烷基甲酮进行了还原. 在β-DG和α-DG胶束中所得到的还原产物苯基烷基甲醇均具有不同程度的光学活性, 其中苯基乙基甲酮在β-DG胶束中的还原可达到98%e.e.的立体选择性. 根据高疏水性受物不能被还原以及在阴离子胶束(Sβ-DGU)中受物难以还原的实验结果. 得出还原反应在靠近胶束极性头基层的内侧进行, 并提出了二分子糖苷与BH4^-形成的分子间负氢离子配合物是不对称还原得以产生的关键. 上述推论被加入适量的非手性阳离子表面活性剂(CTAB)与β-DG所形成的混合胶束可充分抑制还原反应的立体选择性这一实验事实所证实.     

Removal of organic dyes from water by liquid-liquid extraction using reverse micelles

In the present work, solvent extraction using reverse micelles is proposed for the removal of organic dyes from water. In this approach, the dye is solubilized in the aqueous core of the reverse micelles, which are present in the organic phase. The organic phase is subsequently separated from the aqueous phase leading to signifi-cant removal of dye. Experimental results reveal that the electrostatic interaction between the oppositely charged surfactant head group present in the reverse micelles and the dye molecule plays a key role in the separation. The removal of the anionic methyl orange dye from water is carried out in the presence of cationic hexadecyltrimethyl ammonium bromide surfactant, whereas the removal of the cationic methylene blue dye is carried out in the presence of anionic sodium dodecylbenzene sulfonate surfactant. Amyl alcohol is used as the solvent. The influence of parameters such as dye concentrations, surfactant concentrations, pH, and KCl and NaBr concentrations on the percentage removal of dye was studied. The percentage removal of dye is decreased with the increase in dye concentration in the feed. The increase in surfactant concentration resulted in higher dye removal, because more reverse micelles could be hosted in the organic phase. The increase in aqueous phase pH resulted in enhanced removal of methyl orange from water, while in the case of methylene blue the percentage removal decreased. The increase in KCl and NaBr concentrations resulted in decreased percentage removal of methylene blue, whereas the percentage removal of methyl orange was increased. The effect of pH and salt concentration is explained based on charge transfer mechanism and electrostatic interactions and dye-surfactant complex formation.     

利用交联杏仁粉作为廉价而稳定的催化剂通过优化逆水解反应体系显著提高长链烷基糖苷的平衡得率(英文)

使用酶法合成了一系列不同烷基链长的β-D-烷基葡萄糖苷.结果表明,除甲基糖苷外,烷基碳链越长,反应初速度越低,糖苷的最终收率越低.从热力学角度系统地研究了这些糖苷合成的平衡常数和吉布斯自由能变化.通过改变反应的平衡,提高了长链烷基糖苷的最终收率.当水含量从10%降至5%(v/v),使用叔丁醇作为共溶剂,添加0.1mol/L葡萄糖作为底物时,癸基糖苷的平衡得率从1.9%提高至6.1%.除了其他长链的烷基糖苷外,庚基糖苷也显示了明显的表面活性剂活性.     

How can temperature affect reverse micellar extraction using sucrose fatty acid ester?

The reverse micellar extraction of lysozyme using sucrose fatty acid ester was found to be greatly affected by the temperature in the extraction process. For example, lysozyme was perfectly extracted from the feed aqueous phase to the reverse micellar organic phase at 25°C, while it was not extracted at 5°C at all. After entrapping lysozyme into the reverse micelles, lysozyme was recovered from the reverse micellar organic phase to the recovery aqueous phase only by decreasing the temperature in the backward extraction. Moreover, lysozyme solubilized in the reverse micellar organic solution could be recovered without the recovery aqueous solution at 3°C, and its activity was retained at 95%.     

Extraction equilibrium of indium(III) from nitric acid solutions by di(2-ethylhexyl)phosphoric acid dissolved in kerosene

The extraction equilibrium of indium(III) from a nitric acid solution using di(2-ethylhexyl) phosphoric acid (D2EHPA) as an acidic extractant of organophosphorus compounds dissolved in kerosene was studied. By graphical and numerical analysis, the compositions of indium-D2EHPA complexes in organic phase and stoichiometry of the extraction reaction were examined. Nitric acid solutions with various indium concentrations at 25 °C were used to obtain the equilibrium constant of InR? in the organic phase. The experimental results showed that the extraction distribution ratios of indium(III) between the organic phase and the aqueous solution increased when either the pH value of the aqueous solution and/or the concentration of the organic phase extractant increased. Finally, the recovery efficiency of indium(III) in nitric acid was measured.     

Influence of the hydrophobic tail of alkyl glucosides on their ability to solubilize stratum corneum lipid liposomes

The lytic interactions of a series of alkyl glucosides (alkyl chain lengths ranging from C₈ to C₁₂) with liposomes formed by a mixture of lipids modeling the stratum corneum (SC) lipid composition were investigated. The surfactant-to-lipid molar ratios (Re) and the normalized bilayer/aqueous phase partition coefficients (K) were determined by monitoring the changes in the static light-scattering (SLS) of the system during solubilization. The fact that the free surfactant concentrations were always similar to their critical micelle concentrations indicates that the liposome solubilization was mainly ruled by the formation of mixed micelles. At the two interaction levels studied (100 and 0% SLS) the nonyl glucoside showed the highest ability to saturate and to solubilize liposomes (lowest Re values), whereas the dodecyl glucoside showed the highest degree of partitioning into liposomes or affinity with these structures (highest K values). Comparison of the data for octyl glucoside with that reported for the interaction of this surfactant with phosphatidylcholine (PC) liposomes shows that whereas the SC lipid liposomes were more resistant to the action of this surfactant (higher Re values), its degree of partitioning into SC bilayers was both in the saturation and solubilization of liposomes similar to that exhibited in PC vesicles (similar K values). Received: 27 November 2000/Accepted: 19 February 2001     

Solubilization of two organic dyes by cationic ester-containing gemini surfactants

Solubilization of two different types of organic dyes, Quinizarin with an anthraquinone structure and Sudan I with an azo structure, has been studied in aqueous solutions of a series of cationic gemini surfactants and of a conventional monomeric cationic surfactant, dodecyltrimethylammonium bromide (DTAB). Surfactant concentrations both above and below the critical micelle concentration were used. The concentration of solubilized dye at equilibrium was determined from the absorbance of the solution at λ(max) with the aid of a calibration curve. The solubilization power of the gemini surfactants was higher than that of DTAB and increased with increasing alkyl chain length. An increase in length of the spacer unit resulted in increased solubilization power while a hydroxyl group in the spacer did not have much effect. Ester bonds in the alkyl chains reduced the solubilization power with respect to both dyes. A comparison between the absorbance spectra of the dyes in micellar solution with spectra in a range of solvents of different polarity indicated that the dye is situated in a relatively polar environment. One may therefore assume that the dye is located just below the head group region of the micelle. Attractive π-cation interactions may play a role for orienting the dye to the outer region of the micelle.     

Solvent extraction of arsenic(V) with dispersed ultrafine magnetite particles.

The solvent extraction of arsenic(V) was investigated using heptane containing ultrafine magnetite particles and hydrophobic ammonium salt. Arsenic(V) was favorably extracted from aqueous solutions of pH ranging over 2-7, where the distribution ratio (10(3)) was independent of the pH. Although the addition of alkyl ammonium salt improved the phase separation, no notable influence was observed on the extraction of arsenic(V). Oleic acid suppressed the distribution ratio of arsenic(V) when the concentration exceeded 10(-2) M. Sulfate did not interfere with the extraction, while the presence of more than 10(-3) M phosphate decreased the distribution ratio. Metal cations including calcium(II), manganese(II), cobalt(II), nickel(II), copper(II), zinc(II) and lanthanum(III) did not give any serious interference up to the 10(-4) M level. According to equilibrium and kinetic studies, the extraction of arsenic(V) can be interpreted by the adsorption of H2AsO4- onto the surface of dispersed magnetite particles. The relationship between the amount of arsenic(V) extracted in the organic phase and that remaining in an aqueous phase followed a Langmuir-type equilibrium equation. The maximum uptake capacity was determined to be 4.8 x 10(-4) mol/g-magnetite (36 mg As/g). The arsenic(V) extracted in the organic phase was quantitatively recovered by back-extraction with an alkaline solution.     

Liquid-liquid extraction of palladium(II) from hydrobromic acid media by hexadecylpyridinium bromide.

A simple and rapid liquid-liquid extraction of palladium has been studied involving ion-pairing of bromocomplexes of palladium(II) with hexadecylpyridinium bromide (HDPB) dissolved in chloroform. The stoichiometry and distribution of (HDP)2PdBr4 between the aqueous and organic phase was investigated by spectrophotometric mole ratio method. The extraction efficiency of palladium(II) by HDPB was studied as a function of several variables: acid, salt, surfactant concentration and equilibrium time. The results showed that PdBr4(2-) extraction could be explained by assuming the formation of (HDP)2PdBr4 complexes in the aqueous solution and transfer to organic phase. The extraction was fast and the shaking time was only a few min. The average recovery of palladium(II) from an aqueous solution containing 10 microg/ml of analyte was 99% with an RSD% of 0.95. The percentage recovery of 0.2 microg/ml palladium(II) was 96%.     

电解质水溶液在丙酸十二铵-四氯化碳溶液中的增溶

表面活性剂在非极性溶剂中形成的反胶束在催化反应、光化学、蛋白质苹取分离等方面有着广泛的应用问．这些应用与反胶束的性质有着密切的关系，而增溶水后的反胶束其形状和大小都会发生很大的变化．增溶不同水量的反胶束的微极性、酸碱性、微勤度等已有不少文献报导［2－5］．一些不溶于非极性溶剂而溶于水的物质可以溶解在非极性溶剂中的反胶束核心水团中，这个现象被称为二次增溶．其中，电解质的二次增溶对于研究配体转换反应。酶催化反应问及改变反胶束内部的微环境有着十分重要的作用，Aebi和Weibush回首先研究了有水存在时N。CI在A…     

葡萄糖苷特异性固相萃取固定相的合成、表征及应用

以马来酰亚胺基修饰凝胶载体,通过β-葡萄糖胺和2-亚氨基硫代烷盐酸盐将作为配基的β-葡萄糖脒连接到载体上,合成了一种葡萄糖苷特异性固相萃取固定相,并对其固相萃取性能进行了表征.该固定相对葡萄糖苷具有特异性识别,并成功用于固相萃取分离葡萄糖苷.     

吲哚方酸菁染料在表面活性剂水溶液中的光降解

考察了4种含有不同N位取代基的对称吲哚方酸菁染料在阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)、阴离子表面活性剂十二烷基硫酸钠(SDS)和非离子表面活性剂曲拉通(TX-100)水溶液中的光降解行为,结果表明,表面活性剂对染料分子具有保护作用,其影响大小为CTAB>TX-100>SDS,分子中有羧基的染料受影响程度最大。在表面活性剂浓度较低时,染料光降解程度随着表面活性剂浓度的增加而增加,但形成胶束后,染料的光降解程度则随着表面活性剂浓度的升高而降低。     

Characterization of alkyl polyglycosides by both reversed-phase and normal-phase modes of high-performance liquid chromatography

Alkyl polyglycosides today represent the most important sugar surfactant. Nonionic sugar surfactants produced via different synthetic routes are mixtures of alkyl homologues, oligomers, anomers and isomers. Alkyl homologues and oligomers of alkyl mono- and diglucosides were separated by reversed-phase high-performance liquid chromatography (HPLC) with methanol-water as the mobile phase using a gradient elution. The gradient was optimized in respect to a simultaneous separation of alkyl glycosides according to their alkyl chain length and alkyl polyoxyethylene glucosides with regard to their length of the polyoxyethylene spacer. The separation of alkyl glycosides into alpha- and beta-anomers was carried out by normal-phase HPLC with isooctane-ethyl acetate (60:40, v/v)-2-propanol in the gradient mode. Light scattering detection was used. Matrix-assisted laser desorption ionization time-of-flight mass spectra of alkyl glucosides and dodecyl glucosides with oxyethylene spacer groups are presented.     

The study of the partitioning mechanism of methyl orange in an aqueous two-phase system

An aqueous two-phase system of dodecyl triethylammonium bromide (C₁₂NE, cationic surfactant) and sodium dodecyl sulfate (SDS, anionic surfactant) mixture is proposed for the extraction of some dyes and porphyrin compounds. Transparent two phase-systems are formed when the surfactant concentrations and C₁₂NE/SDS ratios are in certain regions. In this study, the aqueous two phase-systems were prepared by mixing 0.1 mol l⁻¹ C₁₂NE and SDS with a molar ratio of 1.7:1.0. The results showed that negatively charged chlorophyll (sodium copper chlorophyllin) and positively charged dye (methyl violet) were efficiently extracted into the upper phase. The negatively charged methyl orange (pH>7) was moved into the upper phase mostly while amphoteric methyl orange (pH<3) was distributed in the two phases uniformly. Except for hydrophobic force, charge interaction between solute and surfactant also play an important role in the extraction process.     

Analysis of organochlorine pesticides in wine by solvent bar microextraction coupled with gas chromatography with tandem mass spectrometry detection

A solvent bar microextraction (SBME) technique combined with gas chromatography/tandem mass spectrometry (GC/MS/MS), for the determination of selected organochlorine pesticides (OCPs) in wine samples, is described. In this work the OCPs were extracted and dissolved in a 2-microL aliquot of organic extraction solvent (n-tetradecane) confined within a 1.7-cm length of hollow fiber. Both ends of the hollow fiber (solvent bar) were sealed, and it was placed in an aqueous sample solution for extraction. The effects of solvent selection, sample agitation, extraction time, extraction temperature, and salt concentration on the SBME performance were optimized. The influence of aqueous sample/organic solvent phase ratio was further investigated in detail. High enrichments (1900-7100-fold) could be obtained at an aqueous sample/organic solvent volume ratio of 20 mL/2 microL in this study. Good extraction reproducibility was obtained with relative standard deviation (RSD) values below 12.6%. Comparisons of sensitivity and precision between SBME and dynamic hollow-fiber liquid-phase microextraction were also investigated.     

Preparation and Evaluation of a Molecular Recognition Bionic Solid Phase Extraction Column for Separation of Glucosides

A molecular recognition bionic solid phase extraction (SPE) column for separation of glucosides has been prepared using a positively charged β‐glucosylamidine as the ligand in which a glycon moiety is connected via an N‐glycoside linkage. β‐Glucosylamidine, highly potent and selective inhibitors of β‐glycosidase, is immobilized through a one‐step synthesize procedure involving the addition of β‐glucosylamine and 2‐iminothiolane. HCl simultaneously to a matrix modified with maleimido groups via an appropriate spacer to give a molecular recognition absorbent for β‐glucosides. N‐octyl‐β‐D‐glucopyranoside and β‐D‐galactopyranoside or α‐D‐mannopyranoside was directly chromatographed through the bionic chromatographic column, resulting in a much stronger retention of β‐D‐glucopyranoside than β‐D‐galactopyranoside and α‐D‐mannopyranoside. The retained glucopyranoside could only be eluted by glucose solution. This indicates that the binding of the glucoside was of specific nature that corresponds to the glycon substrate specificity of the glucoside. The ease of preparation and the selective nature of the molecular recognition bionic chromatography should promise a large‐scale preparation of the molecular recognition adsorbent for the purification and removal of glucosides according to their glycon substrate specificity.     

Identification of natural dyes in archeological Coptic textiles by liquid chromatography with diode array detection

Reversed-phase HPLC with diode-array UV-Vis spectrophotometric detection has been used for identification of natural dyes in extracts from wool and silk fibres from archeological textiles. The examined objects originate from 4th to 12th Century Egypt and belong to the collection of Early Christian Art of the National Museum in Warsaw. Extraction from fibres was carried out with HCl solution containing ethanol or with warm pyridine. As the main individual chemical components of natural dyes, anthraquinone, indigoid and flavonoid dyes including alizarin, purpurin, luteolin, apigenin, carminic acid, ellagic acid, gallic acid, laccaic acids A and B and indigotin were found. For pyridine extracts another mobile phase with an optimized gradient of organic modifier concentration was used. With such an eluent the appearance of double peaks for indigotin and indirubin was eliminated. For acidic extraction of dyes from fibres, ethanol was used. Due to its higher boiling point than methanol it evaporates slower from the extraction solution enabling a more efficient extraction of dyes.     

Simultaneous determination of carminic acid, riboflavine, curcumin and erythrosine by derivative spectrophotometry and ratio spectra derivative

A quaternary mixture of carminic acid, riboflavine, curcumin and erythrosine can be resolved with a previous extraction step into metyl-isobutyl ketone and, resolving the binary mixtures obtained in the aqueous phase and organic phase, using derivative spectrophotometry on the basis of the zero-crossing measurements in the first derivative spectra as well as the first derivative of ratio spectra. The conditions of extraction established and the proposed methods have been tested to determine these colorants in several synthetic mixtures of four dyes, obtaining good recoveries. The methods have been applied in yoghurt samples spiked with the dyes.