H＋对水溶液中脱氧胆酸钠聚集体的影响

运用pH滴定、傅立叶变换红外光谱、紫外可见光谱、激光光散射谱、ICP和元素分析等方法研究了H＋的加入对水溶液中脱氧胆酸钠（NaDC）聚集体的影响.结果表明,浓度大于cmc的NaDC水溶液具有一定的缓冲能力,NaDC浓度越高,缓冲能力越大;随溶液中H＋浓度的增加,首先形成质子化胶团,质子化胶团通过酸盐结构的氢键作用使NaDC初级胶团长大,形成较大的高级胶团,甚至形成凝胶体,最终形成HnNam(DC)n＋m沉淀.     

Modelling of retention behaviour of solutes in micellar liquid chromatography

In micellar liquid chromatography (MLC), the resolution for a given multi-component mixture can be optimized by changing several variables, such as the concentrations of surfactant and organic modifier, the pH and temperature. However, this advantage can only be fully exploited with the development of mathematical models that describe the retention and the separation mechanisms. Several reports have appeared recently on the possibilities of accurately predicting the solute retention in MLC. Although the retention and selectivity may strongly change with varying concentrations of surfactant, organic modifier and/or pH, the observed changes are very regular, and are well described by simple models. This characteristic enables a successful prediction of retention times and compensates the negative effect of the broad and tailed chromatographic peaks obtained for some solutes when micellar eluents are used. An overview of the models proposed in the literature to describe the retention behaviour in pure micellar eluents and micellar eluents containing an organic modifier, at a fixed pH or at varying pH, is given. The equations derived permit the evaluation of the strength of micelle-solute and stationary phase-solute interactions. The prediction of the retention based on molecular properties and the use of neural networks, together with the factors affecting the prediction capability of the models (linearization of the equations, dead time, critical micellar concentration, ionic strength and temperature) are commented on. The strategies used for the optimization of resolution are also given.     

界面微环境中双亲卟啉的光谱研究

用敏感于微环境变化的UV-Vis光谱,研究了在SDS胶束微环境中,双亲原卟啉P1对体相pH值的依赖关系。体相pH值由弱碱性到强酸性改变的过程中,P1在SDS胶束内存在明显等色点,为一典型的双组分平衡,同时其质子化峰吸收强度逐渐增强,表明P1在胶束内发生了质子化;体相pH值从弱碱到强碱变化时,P1的Soret带红移,吸光度变小,半峰宽加大,这是卟啉从SDS胶束内核转移到胶束表面的结果,由此证明改变pH值可以实现卟啉跨膜转移的控制。     

电解质对两性药物分子盐酸氯丙嗪的胶团生长的影响

The effect of electrolytes on the micellar behavior of an amphiphilic drug,chlorpromazine(CPZ)hydroehloride,was studied using cloud point(CP)and dye solubilization techniques.In the presence of KBr,increase because of deprotonation of drug molecules at high pH. The visible absorbance increased(due to dye solubilization)with the increase in pH from 6.5 to 6.9,which indicated micellar growth.At fixed pH(6.7),addition of inorganic salts(KF,KC1,effecfiveness being in the order:F-Na >K ,which Was explained by considering cognizance of their hydrated radii.Compared with anions,their effect was small.Increase in[CPZ]caused micellar growth and hence the CP as well as the visible absorbance increased.The overall behavior Was discussed in terms of electrostatic interactions and micellar growth.     

Effect of pH on kinetics of the decay of the radicals formed during photolysis of 2,2,4,6-tetramethyl-1,2-dihydroquinoline in aqueous and micellar solutions

Kinetics of the decay of the transient radicals formed from 2,2,4,6-tetramethyl-1,2-dihydroquinoline (TMQ) in aqueous and micellar solutions of sodium dodecyl sulfate were studied by flash photolysis as a function of pH. In aqueous and micellar solutions of TMQ the mechanism of the decay of the transient species and the reaction products are different from those in homogeneous organic solutions. The decay of the transient radicals follows first-order kinetics in the entire range of pH under consideration in both aqueous and micellar solutions. In aqueous solutions at pH 9–12, the decay rate constant decreases from 25.3 to 3.7 s⁻¹. In micellar solutions at different pH, different types of micellar catalysis were observed. At pH 1, the rate constant in a micellar solution is slightly lower than that in an aqueous solution. At pH 3–11, the decay rate constant increases (positive micellar catalysis). The apparent rate constant depends linearly on the concentration of TMQ in micelles. The rate constant for the reaction of the transient radical cation with TMQ was determined (200 L mol⁻¹ s⁻¹). At pH>13, the decay rate constant in micelar solutions is lower than that in aqueous solutions (negative micellar catalysis). Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 703–708, April, 1997.     

Enantioseparation of phenothiazines in cyclodextrin-modified micellar electrokinetic chromatography

In this study, enantioseparations of five phenothiazines in cyclodextrin (CD)-modified micellar electrokinetic chromatography (MEKC) were investigated using a citrate buffer containing tetradecyltrimethylammonium bromide (TTAB) as a cationic surfactant at low pH. Beta-cyclodextrin (beta-CD) and hydroxylpropyl-beta-CD (HP-beta-CD) were selected as chiral selectors. The results indicate that the separation window is greatly enlarged by beta-CD concentration and that the separability and selectivity of phenothiazines are remarkably influenced by the concentrations of both beta-CD and TTAB, as well as buffer pH. The interaction of thioridazine with beta-CDs is considerably reduced in the presence of TTAB micelles due to competitive complexation of thioridazine with TTAB micelles, which is pH-dependent. As a result, effective enantioseparation of thioridazine is simultaneously achievable with that of trimeprazine and promethazine or ethopropazine in MEKC with addition of either beta-CD or HP-beta-CD, respectively, to a micellar citrate buffer containing TTAB at pH 3.5. Better enantioresolution of thioridazine in MEKC than in capillary zone electrophoresis can be obtained.     

A Self-Assembling Flavin for Visible Photooxidation

A new flavin-based gelator is reported which forms micellar structures at high pH and gels at low pH. This flavin can be used for the photooxidation of thiols under visible light, with the catalytic efficiency being linked to the self-assembled structures present.     

氧氟沙星在胶束体系中的荧光特性及应用

研究发现十二烷基硫酸钠胶束对氧氟沙星荧光有明显的增敏作用，据此建立了直接测定人体尿液中氧氟沙星的等波长差同步荧光光谱法（△λ=90nm）。经样品测定，其线性范围为0．12－3．6mg/L，检出限为0．12mg/L，回收率为92．2％－97．8％，相对标准偏差为1．2％－2．7％。     

Direct serum injection in micellar liquid chromatography. Recovery of serum proteins and assay of hydrophilic drugs

The recovery of serum proteins from reversed-phase and internal-surface reversed-phase (ISRP) silica supports following direct serum injection was investigated using an eluent containing a micellar solution of sodium dodecyl sulphate (SDS). The results indicated that the recoveries of serum proteins were 98-103% for both supports. On the basis of the above findings, the separation and recovery of hydrophilic drugs (cephalosporins and salicylic acid) from human serum were investigated using acidic eluents including micellar solutions of SDS. They were completely separated from the components of serum, and the recoveries were 94-98% despite protein binding. Although the recommended eluent pH range is 6.0-7.5 for the ISRP support, eluents of pH 2-8 can be used with the micellar chromatographic system.     

Selective entrapment of the cationic form of norfloxacin within anionic sodium dodecyl sulfate micelles at physiological pH and its effect on the drug photodecomposition

The binding of the photosensitizing fluoroquinolone (FQ) antibiotic norfloxacin (NX) to sodium dodecyl sulfate (SDS) micelles and the photoreactivity of the NX/SDS complex under physiological pH conditions are investigated by means of absorption and emission spectroscopy, steady-state and laser flash photolysis. It is shown that the photolabile zwitterionic form of NX, which is dominant at physiological pH, is not the most abundant species in the presence of SDS micelles. This medium exhibits a high preference for the cationic form of the drug, which is selectively and successfully entrapped within the micellar cage (K(ass) = 6 x 10(4) M(-1) +/- 3000), becoming the largely dominant species at neutral pH. The effect of this trapping is drastically reflected on both efficiency and nature of the drug photodecomposition. It is observed that the photostability of NX incorporated in the micellar pseudophase increases of more than one order of magnitude if compared to that of the "free" drug. Furthermore, the radical photodecomposition mechanism occurring in phosphate buffered solution is suppressed by the micellar medium and the low photodegradation observed seems to take place preferentially through an ionic pathway. Hopefully, the results presented herein may contribute to a better understanding of the bio-distribution of NX in biological systems and provide helpful and stimulating information in order to get the control of FQ photoreactivity under physiological pH conditions.     

Comparison of C18 silica bonded phases selectivity in micellar liquid chromatography

The paper describes a new test designed in micellar LC (MLC) to compare the commercial C18 stationary phase properties. This test provides the total hydrophobicity, hydrophilicity, steric selectivity, hydrogen bonding, and ion‐exchange capacity properties calculation of the ODS stationary phases. Both the test compounds and chromatographic separation conditions choice for column characterization in MLC are detailed. The chromatographic performance of several stationary phases that are used in MLC was evaluated with specific chromatographic test comprising nine test compounds, possessing different physico‐chemical properties, which were injected on different supports with two micellar mobile phases: one at pH 7.0 (0.075 mol/L SDS and 1.5% v/v 1‐pentanol), and other at pH 2.7 (0.075 mol/L SDS and 1.5% v/v 1‐pentanol adjusted to pH by TFA). Fundamental column chromatographic properties were obtained under these conditions and were treated by hierarchical cluster analysis. From the results of cluster analysis, two closely related groups of columns are distinguished, and it was shown that the chosen column characteristic parameters allow characterizing both sorbent and micellar chromatographic system properties. Eleven columns were analyzed by this test, which allows a comparison of columns with the aim of the selection of suitable and analogous column for the analysis with MLC.     

反胶团相转移法提取青霉素G的研究

报道了非蛋白质类活性物质青霉素Ｇ在反胶团相转移提取中的特性和机理。结果表明，青霉素Ｇ在ＣＴＡＢ／正辛醇：氯仿（４：１，Ｖ／Ｖ）反胶团体系中的相转移提取为离子对静电作用与胶团溶解机理；在室温及ｐＨ值５～８的条件下，提取率在９０％以上，且保持了青霉素的稳定性。     

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.     

用去氧胆酸盐和β-环糊精的毛细管胶束电动色谱拆分手性药物

 用β－环糊精（β－ＣＤ）和去氧胆酸钠（ＳＤＣ）的环糊精改性毛细管胶束电动色谱，实际拆分了ＥＭＤ－５６４３１和扑尔敏两种手性药物，研究了ＳＤＣ和β－ＣＤ浓度及ｐＨ值对分离的影响。初步讨论了分离的机理。认为ＣＤ－ＳＤＣ体系中胶束单体分子几乎均被ＣＤ包合；ＣＤ可能与部分胶束单体包合而存在于ＳＤＣ的胶束中；该拆分体系中ＳＤＣ与β－ＣＤ的浓度比在４∶１～４∶３时拆分效果最好。并发现ＳＤＣ对β－ＣＤ有显著的增溶作用。     

Micellar effects on the electrochemistry of dopamine and its selective detection in the presence of ascorbic acid

The electrochemistry of dopamine (3-hydroxytyramine) was studied by cyclic voltammetry at a glassy carbon electrode in the presence of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) micelles at different pH. The anodic peak potential (E(pa)) and peak current (I(pa)) were found to be remarkably dependent on the charge and the concentration of the surfactant. The E(pa) and I(pa) change abruptly around the critical micellar concentration (CMC) of the surfactants and reach a plateau above the CMC. The E(pa) at the plateau shifts to more positive values in the cationic CTAB micellar solution, e.g. from 180 mV vs SCE in aqueous solution at pH 6.8 to 410 mV in CTAB micelle, whilst it shifts to less positive values in the anionic SDS micellar solution, e.g. 150 mV at pH 6.8. Therefore, the overlapped anodic peaks of dopamine and ascorbic acid in the mixture of the two compounds in aqueous solutions can be separated in CTAB micelles since the micelle shifts the E(pa) of ascorbic acid to less positive values. The two peaks are separated by ca. 400 mV at pH 6.8 in CTAB micelle, hence dopamine can be determined in the presence of 100 times excess of ascorbic acid. In SDS micelle and in the presence of ascorbic acid, the I(pa) of dopamine is greatly enhanced due to the catalytic oxidation of the latter that enables quantitative determination of both compounds.     

利尿剂的胶束色谱分析

用十二烷基硫酸钠（SDS）胶束溶液作为流动相，建立了11种利尿剂的胶束色谱系统分析方法；研究了SDS浓度、流动相的pH、有机改性剂及温度对色谱保留行为的影响，优化了色谱条件，并且不经化学处理直接进样测定了人尿中的烯睾丙内酯；该法适用于兴奋剂中利尿剂的常规分析。     

Investigation of the role of electrolytes and non-electrolytes on the cloud point and dye solubilization in antidepressant drug imipramine hydrochloride solutions

Antidepressant drug imipramine hydrochloride (IMP) is amphiphilic which shows surfactant-like behavior in aqueous solutions. We have studied the effect of adding electrolytes and non-electrolytes on the micellar behavior of IMP by making cloud point (CP) and dye solubilization measurements. The CP of a 100mM IMP solution (prepared in 10mM sodium phosphate (SP) buffer) was found to decrease with increasing pH, both in the absence as well as presence of added salts. Increase in pH increased the visible absorbance of Sudan III dye solubilized in the drug micelles, implying micellar growth. Addition of increasing amounts of salts to 100mM IMP solutions (at pH 6.7) caused continuous increase in CP due to micellar growth. On the basis of these studies, the binding-effect orders of counter- and co-ions have been deduced, respectively, as: Br(-)>Cl(-)>F(-) and Li(+)相似文献   

Influence of Electrolytes on the Micellar Growth of Amphiphilic Drug Chlorpromazine Hydrochloride

The effect of electrolytes on the micellar behavior of an amphiphilic drug, chlorpromazine (CPZ) hydrochloride, was studied using cloud point (CP) and dye solubilization techniques. In the presence of KBr, increase in pH led to decrease in the CP of 50 mmol·L_-1 drug solution (prepared in 10 mmol·L_-1 sodium phosphate (SP) buffer) because of deprotonation of drug molecules at high pH. The visible absorbance increased (due to dye solubilization) with the increase in pH from 6.5 to 6.9, which indicated micellar growth. At fixed pH (6.7), addition of inorganic salts (KF, KCl, and KBr) to drug solutions (50 mmol·L_-1) caused an increase in the CP as well as in the visible absorbance, with effectiveness being in the order: F_- < Cl_- < Br_-. The results were discussed on the basis of counter-ion binding and their effect toward micellar growth. Cations (co-ions) also led to an increase in the CP (and also the visible absorbance), with their effectiveness order being Li₊ > Na₊ > K₊, which was explained by considering cognizance of their hydrated radii. Compared with anions, their effect was small. Increase in [CPZ] caused micellar growth and hence the CP as well as the visible absorbance increased. The overall behavior was discussed in terms of electrostatic interactions and micellar growth.     

Kinetic study and analytical applications of micellar catalyzed reactions of 1-fluoro-2,4-dinitrobenzene with inorganic thioanions using a fluoride-selective electrode

A kinetic study and analytical applications of the CPC micellar catalyzed reactions of 1-fluoro-2,4-dinitrobenzene (FDNB) with inorganic thioanions (sulfide, sulfite and thiosulfafte) using a fluoride-selective electrode is described. Reaction orders (unity for both FDNB and thioanion) and experimental stoichiometric reaction-rate constants were calculated from initial slope measurements (DeltaE/Deltat) at various pH values (4-9). Calibration graphs for quantitative determinations (4.5-45 muM for sulfide, 2.4-75 muM for thiosulfate and 6.6-75 muM for sulfite) are constructed using the initial rate approach. The proposed method has been applied to the determination of sulfide in spiked seawater samples using the multiple standard addition approach with a mean relative error of 5.5%. The application of this micellar catalyzed reaction in the differential kinetic analysis of binary mixtures of sulfide-thiosulfate and sulfite-thiosulfate, using the proportional equations approach at pH 5.5 and 8.0, was unsuccessful due to the interactions of the two analytes, which can be explained using the ion-exchange/pseudophase model of micellar catalysis. However, the use of multiple linear regression approach on a sufficient number of standard binary mixtures can confront this drawback.     

Negative adsorption due to electrostatic exclusion of micelles

Interactions of surfactants with solid substrates are important in the controlling of processes such as flotation, coating, flocculation and sedimentation. These interactions usually lead to adsorption on solids, but can also result in an exclusion of the reagents with dire consequences. In this work electrostatic exclusion of negatively charged dodecylbenzene sulfonate micelles from quartz/water, Bio-Sil/water and alumina/water interfaces has been investigated as a function of pH and ionic strength. Measurable negative adsorption of these surfactants from similarly charged solid/liquid interface was observed in the micellar region. In the case of porous samples with large surface area, comparison of pore size with the micelle size is necessary to avoid any erroneous conclusions regarding the role of electrostatic exclusion in a given system. A theoretical model for the electrostatic exclusion of micelles is developed and used to calculate the adsorption of negatively charged dodecylbenzene sulfonate on negatively charged quartz (pH 7), silica (Bio-Sil A, pH 3) and alumina (pH 11) in the micellar concentration region. The micellar exclusion values calculated using the model are in excellent agreement with the experimental results.