Noncovalent coatings for the separation of synthetic polypeptides by nonaqueous capillary electrophoresis

Recently, we demonstrated the possibility to extend the range of capillary electrophoresis (CE) applications to the separation of non-water-soluble synthetic polymers. This work focuses on the control of the electro-osmotic flow (EOF) and on the limitation of the solute adsorption in nonaqueous electrolytes. For these purposes, different strategies were investigated. For the initial, a viscous additive (ethylene glycol or glycerol) was used in the electrolyte in order to decrease the EOF magnitude and, possibly, to compete with solute adsorption. A second strategy was to modify, before separation, the fused-silica capillary wall by the adsorption of poly(ethylene oxide) (PEO) via hydrogen bonding. The influence of the molecular mass of the adsorbed PEO on the EOF magnitude and direction was studied in electrolytes based on methanol/acetonitrile mixtures containing ammonium ions. For PEO molecular masses above 1000 g/mol, reversed (anodic) EOF were reported in accordance with previous results obtained with PEO covalently bonded capillaries. The influence of the nature and the concentration of the background electrolyte cation on the EOF magnitude and direction were also investigated. A third strategy consisted in modifying the capillary wall by the adsorption of a cationic polyelectrolyte layer. Advantageously, this polyelectrolyte layer suppressed the adsorption of the polymer solutes onto the capillary wall. The results obtained in this work confirm the high potential and the versatility of CE for the characterization of ionizable organic polymers in nonaqueous media.     

A New Category of Liquid Salt--Liquid Ionic Phosphates (LIPs)

Starting with polycationic ammonium and phosphonium salts bearing halide anions previously synthesized in our laboratory, we have prepared a new category of nonaqueous ionic liquids. These new nonaqueous ionic liquids bear either free phosphate anions or partially esterified phosphate anions as the counterions to the ammonium or phosphonium cations. We generally refer to these new species as LIPs (liquid ionic phosphates). We have developed three approaches toward the syntheses of these materials from the halide salts: one using hexafluorophosphoric acid;; a classical ion exchange method; and treatment with the free phosphorus-containing acid under vacuum. The new LIPs, although highly viscous, exhibit significantly high specific conductivities. Unlike ionic liquids bearing tetrafluoroborate of tetrachloroaluminate anions, the LIPs are unreactive toward water. Further, the LIPs bearing simple phosphate anions are soluble in water, unlike their corresponding hexafluorophosphate salts. We have also examined the UV/Vis, fluorescence, and mobility characteristics of the new LIPs.     

非水介质中分酚氧化酶催经羟基化反应的研究

以对甲酚为底物,利用双马铃薯中提取的多酚氧化酶的粗酶液,用多孔玻璃包衣琼脂疏水吸附法将多酚氧化酶固定化,并利用此固定化酶,考察了在非水介质中羟基化反应的最适宜条件,在此条件下催化合成4－甲基邻苯二酚的产率为55．8％。     

非水反相微乳的加溶与电导性质研究

研究了若干非水极性溶剂（甲酰胺、二甲基亚砜和乙腈）及其与水的混合物/AOT/正庚烷反相微乳体系的加溶性质及其电导行为.结果表明，在AOT反相微乳中，非水极性溶剂的最大加溶量均远小于水的加溶量.其最大加溶量顺序为二甲基亚砜< 甲酰胺< 乙腈< 水.甲酰胺和乙腈与水的加溶相互抵制，而水在一定范围内可促进二甲基亚砜的加溶.非水反相微乳的电导率随加溶量的变化规律与含水反相微乳体系类同，但到达电导率极大值和出现渗滤时的加溶量明显比含水反相微乳 体系的要小.     

Structural and calorimetric investigations on nonaqueous liquid crystals and gel phases in the binary system K-stearate/glycerol

The K-stearate/glycerol (KC₁₈/Gl) binary system was studied at mole fractions of stearate of x _KC18 = 0.10, 0.25, 0.30 and 0.50. Small- and wide-angle X-ray diffraction (XRD) measurements were combined with differential scanning calorimetry (DSC) measurements at different temperatures. The investigations were intended to verify the previously published phase diagram and were targeted at the confirmation of the gel-like (G₁) phase and the isotropic (I) phase. The XRD and DSC measurements lead to the conclusion that the G₁ phase as well as the I phase, the existence of which had been proposed from texture observations, do in fact not exist. Consequently, a correction of the preliminary phase diagram is given. This corrected phase diagram reveals the crystalline phase (C) ⇆ gel phase (G) ⇆ hexagonal phase (H_α) ⇆ isotropic, micellar phase phase transitions for low KC₁₈ concentrations of x _KC18 = 0.15–0.3 and the C ⇆ G ⇆ lamellar phase (L_α) phase transitions for concentrations about or higher than x _KC18 = 0.35. The C, G, L_α and H_α phases have been further characterized by structural parameters (characteristic d values) as a function of temperature. The phase transitions C ⇆ G, G ⇆ L_α and G ⇆ H_α correlate with sharp shifts in the d value of the first small-angle reflections. Received: 20 April 1999 Accepted: 28 July 1999     

Separation and determination of the anthraquinones in Xanthophytum attopvensis pierre by nonaqueous capillary electrophoresis

A nonaqueous capillary electrophoresis (NACE) method with direct on-column UV detection has been developed for the separation of the pharmaceutically important anthraquinones from the total grass of Xanthophytum attopvensis pierre extract. The separation of three main anthraquinones (1-hydroxy-2-methoxy-3-hydroxymethyl-9, 10-anthraquinone-1-O-β-d-glucoside (1), rubiadin- 1-methylether (2) and 1-methoxy-2-formyl-3-hydroxy-9, 10-anthraquinone (3)) was optimized with respect to concentration of sodium cholate (SC) and acetic acid, addition of acetonitrile (ACN), and applied voltage. Baseline separation was obtained for the three analytes within 5 min using a running buffer containing 50 mM sodium cholate (SC), 1.0% acetic acid and 40% ACN in methanol. The method of NACE for the separation and determination of bioactive ingredient in traditional Chinese medicines was discussed.     

Nonaqueous seeded growth of flower-like mixed-phase titania nanostructures for photocatalytic applications

A nonaqueous seeded-grown synthesis of three-dimensional TiO₂ nanostructures in the benzyl alcohol reaction system was reported. The synthesis was simple, high-yield, and requires no structural directing or capping agents. It could be largely accelerated by applying microwave heating. The TiO₂ nanostructures had a unique flower-like morphology and high surface area. Furthermore, the structural analyses suggested that the nanostructures had a non-uniform distribution of crystalline phases, with the inner part rich in anatase and the outer part rich in rutile. After heat treatments, the mixed-phase TiO₂ nanostructures exhibited high photocatalytic activities for the photodegradation of methylene blue as compared to Degussa P25. The high photoactivities may be associated with the high surface area and the synergistic effect resulting from the anisotropic mixed-phase nanostructures. The results demonstrate the uniqueness of the nonaqueous seeded growth and the potential of the TiO₂ nanostructures for practical applications.     

Stabilities and Transfer Activity Coefficients from Water to Polar Nonaqueous Solvents of Benzo-15-Crown-5- and 15-Crown-5-Alkali Metal Ion Complexes

Stability constants (K_ML) of 1 : 1 benzo-15-crown-5 (B15C5) complexes with alkali metal ions were conductometrically measured in water at 25°C. Transfer activity coefficients of B15C5 and 15-crown-5 (15C5) from water to polar nonaqueous solvents were determined at 25°C. By using these data and the literature values, transfer activity coefficients of the B15C5 and 15C5 complexes with alkali metal ions from water to the polar nonaqueous solvents were calculated to study the solute-solvent interaction of the crown ether complexes. The stability of the B15C5 complex is lower in water than in any other nonaqueous solvent. The K_ML value for B15C5 is always smaller than the corresponding K ML value for 15C5. The interaction of the B15C5 or the 15C5 complex with the solvents depends on the alkali metal ion in the crown cavity. All the B15C5 and 15C5 complexes undergo hydrophobic hydration, which is particularly stronger for the B15C5 complexes with Na⁺ and K⁺. The unexpectedly lowest stability of the B15C5- or the 15C5-alkali metal ion complex in water among all the solvents is caused by the hydrogen bonding between ether oxygen atoms of uncomplexed B15C5 or 15C5 and water.     

Derivatizat Ion of Primary Aromatic Amines with Fluorescamine

Abstract

Fluorescamine forms stable, fluorescent derivatives with sterically-unhindered primary aromatic amines in both aqueous (borate buffer, pH 9/acetonitrile) and nonaqueous (pyridine/-acetonitrile) media. Aromatic amines with a substituent such as a methyl group or an aromatic ring ortho to the amine functionality either derivatized poorly or not at all because of steric hindrance.     

非水反相高效液相色谱法测定海藻中3种叶黄素类化合物

建立了非水反相高效液相色谱测定不同种类海藻中3种叶黄素类化合物的方法。采用超声波辅助提取海藻中的叶黄素类化合物,选用Alltima C18色谱柱分离,以甲醇-乙腈-丙酮为流动相系统,梯度洗脱分离,检测波长445 nm。结果表明,在选定的色谱条件下,待分析的3种叶黄素类化合物与其他化合物分离良好,在一定浓度范围内线性关系良好(紫黄素:6.24～624μg/L,环氧玉米黄素:4.56～456μg/L,玉米黄素:5.60～560μg/L)。该方法适用于不同海洋藻类中3种叶黄素类化合物的定量分析。