Synergistic extraction of rare earths by mixture of bis(2,4,4-trimethylpentyl)phosphinic acid and Sec-nonylphenoxy acetic acid

Synergistic extraction of trivalent rare earths (RE=Sc, Y, La, Gd, Yb) from hydrochloride medium using mixture of bis(2,4,4-trimethylpentyl)phosphinic acid (HL, Cyanex272) and Sec-nonylphenoxy acetic acid (HA, CA-100) in n-heptane has been studied. The synergistic enhancement coefficients were observed for La (1.30), Gd (1.97), Y (3.59), Yb (8.21) and Sc (14.41). The results indicated yttrium was extracted into n-heptane as YH(5)A(4)L(4) mixed species instead of Y(HL2)(3), Y(OH)(2)A(HA)(3) which were extracted by Cyanex272 and CA-100, respectively. A cation exchange mechanism was proposed and further clarified by IR spectra. The equilibrium constants, formation constants and thermodynamic functions such as Delta G, Delta H and Delta S were determined. The Cyanex272 + CA-100 system not only enhanced the extraction efficiency of RE but also improved the selectivities significantly. The mutual separation factors of these ions suggested the mixture system would be of practical value in extraction and separation of rare earths.

Theoretical representation of shear and pressure influence on the phase separation behavior of PVME/PS mixture

In the framework of lattice fluid model, the Gibbs energy and equation of state are derived by introducing the energy (E-s) stored during flow for polymer blends under shear. From the calculation of the spinodal of poly(vinyl methyl ether) (PVME) and polystyrene (PS) mixtures, we have found the influence of E., an equation of state in pure component is inappreciable, but it is appreciable in the mixture. However, the effect of E, on phase separation behavior is extremely striking. In the calculation of spinodal for the PVME/PS system, a thin, long and banana miscibility gap generated by shear is seen beside the miscibility gap with lower critical solution temperature. Meanwhile, a binodal coalescence of upper and lower miscibility gaps is occurred. The three points of the three-phase equilibrium are forecasted. The shear rate dependence of cloud point temperature at a certain composition is discussed. The calculated results are acceptable compared with the experiment values obtained by Higgins et at. However, the maximum positive shift and the minimum negative shift of cloud point temperature guessed by Higgins are not obtained, Furthermore, the combining effects of pressure and shear on spinodal shift are predicted.

Rapid analysis of steroidal saponin mixture using electrospray ionization mass spectrometry combined with sequential tandem mass spectrometry

Using electrospray ionization mass spectrometry (MS) combined with sequential tandem MS(ESI-MSn), two major steroidal saponins extracted from Tribulus terrestris were studied, and considerable useful structural information was obtained. The structure of the proposed known steroidal saponin was verified, and the structure of the unknown saponin was investigated using MSn experiments. Some special fragment ions were also observed, and the corresponding fragmentation mechanisms were investigated which are characteristic for steroidal saponins and can give some information on the linkage position of some sugar groups in saponins. This methodology has been established as a powerful tool for the rapid, comparative analysis of mixtures such as crude plant extracts. (C) 1998 John Wiley & Sons, Ltd.

Asymmetric polymerization of the mixture of TrMA and MMA initiated by chiral complexes

A mixture of triphenylmethyl methacrylate (TrMA) and methyl methacrylate (MMA) was polymerized with chiral anionic initiator, such as fluorenyl lithium-(-)-sparteine [FlLi-(-)-Sp] and fluorenyl lithium-(+)-2S,3S-dimethoxy-1,4-bis(dimethylamino) butane [FlLi-(+)-DDB] in toluene at -78 degrees C. The results show that after the stable helix formed, when FlLi-(+)-DDB was used as the initiator, TrMA and MMA could be copolymerized, whereas when FlLi-(-)-Sp was used, the two monomers tended to be selectively polymerized into two polymers. This phenomenon has been explained by the existence of helix-selective polymerization. (C) 1997 John Wiley & Sons, Inc.

A novel structure analysis method for lanthanide complex - None paramagnetic shift tri-lanthanide mixture method

A new structure analysis method for lanthanide complexes was proposed, that is, none paramagnetic shift tri-lanthanide mixture method, It was found that the paramagnetic induced shift could be cancelled by mixing three kinds of paramagnetic lanthanide ions in appropriate proportion. As a result, the chelating sites would he seen simplely from the half widths and the relative distances between lanthanide ion and the ligand nucleus could be calculated from the relaxation time (T-1) or the half width. Care should be addressed that the analysis method is suitable for the systems in which intramolecular arrangements and intermolecular ligand exchanges are relatively fasten NMR time scale used.

STATISTICAL THERMODYNAMICS IN THE FRAMEWORK OF THE LATTICE FLUID MODEL .2. BINARY MIXTURE OF POLYDISPERSE POLYMERS OF SPECIAL DISTRIBUTION

In this paper, the Gibbs free energy, the equation of state and the chemical potentials of polydisperse multicomponent polymer mixtures are derived. For general binary mixtures of polydisperse polymers, we also give the Gibbs free energy, the equation of

STATISTICAL THERMODYNAMICS IN THE FRAMEWORK OF THE LATTICE FLUID MODEL .3. BINARY MIXTURE OF POLYDISPERSE POLYMERS OF SPECIAL DISTRIBUTION WITH STRONG-INTERACTIONS

For a binary mixture of polydisperse polymers with strong interactions, the free energy, the equation of state, the chemical potentials and the spinodal are formulated on the basis of the lattice fluid model. Further, the spinodal curves for the system wi

FLUORESCENCE SPECTROSCOPIC STUDIES ON THE DYE MIXTURE SYSTEM C440/C540/Saf.-T

The fluorescence spectra and lifetimes of the ternary due mixture C440/C540/Saf. -T were studies. Experimental results indicated that there are efficient energy transfer among these three components of the dye system. Consequently this system may he expected to be a potemtial eandidate of laser dye giving out output in three different wavelength regions. From. the relation of donor fluorescence lifetime as a function of aceeptor concentration and the relation of accepter fluorescence intensity as a funotion...

In vivo growth-inhibition of S 180 tumor by mixture of 5-Fu and low molecular lambda-carrageenan from Chondrus ocellatus

POLYSACCHARIDES; ANTICOAGULANT; SURVIVAL

Development of a sensitive fluorescent derivatization reagent 1,2-benzo-3,4-dihydrocarbazole-9-ethyl chloroformate (BCEOC) and its application for determination of amino acids from seeds and bryophyte plants using high-performance liquid chromatography with fluorescence detection and identification with electrospray ionization mass spectrometry

A pre-column derivatization method for the sensitive determination of amino acids and peptides using the tagging reagent 1,2-benzo-3,4dihydrocarbazole-9-ethyl chloroformate (BCEOC) followed by high-performance liquid chromatography with fluorescence detection has been developed. Identification of derivatives was carried out by liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS/MS). The chromophore of 2-(9-carbazole)-ethyl chloroformate (CEOC) reagent was replaced by 1,2-benzo-3,4-dihydrocarbazole functional group, which resulted in a sensitive fluorescence derivatizing reagent BCEOC. BCEOC can easily and quickly label peptides and amino acids. Derivatives are stable enough to be efficiently analyzed by high-performance liquid chromatography. The derivatives showed an intense protonated molecular ion corresponding m/z (M + H)(+) under electrospray ionization (ESI) positive-ion mode with an exception being Tyr detected at negative mode. The collision-induced dissociation of protonated molecular ion formed a product at m/z 246.2 corresponding to the cleavage of C-O bond of BCEOC molecule. Studies on derivatization demonstrate excellent derivative yields over the pH 9.0-10.0. Maximal yields close to 100% are observed with a 3-4-fold molar reagent excess. Derivatives exhibit strong fluorescence and extracted detzvatization solution with n-hexane/ethyl acetate (10:1, v/v) allows for the direct injection with no significant interference from the major fluorescent reagent degradation by-products, such as 1,2-benzo-3,4-dihydrocarbazole-9-ethanol (BDC-OH) (a major by-product), mono- 1,2-benzo-3,4-dihydrocarbazole-9-ethyl carbonate (BCEOC-OH) and bis-(1,2-benzo-3,4-dihydrocarbazole-9-ethyl) carbonate (BCEOC)(2). In addition, the detection responses for BCEOC derivatives are compared to those obtained with previously synthesized 2-(9-carbazole)-ethyl chloroformate (CEOC) in our laboratory. The ratios AC(BCEOC)/AC(CEOC) = 2.05-6.51 for fluorescence responses are observed (here, AC is relative fluorescence response). Separation of the derivatized peptides and amino acids had been optimized on Hypersil BDS C-18 column. Detection limits were calculated from 1.0 pmol injection at a signal-to-noise ratio of 3, and were 6.3 (Lys)-177.6 (His) fmol. The mean interday accuracy ranged from 92 to 106% for fluorescence detection with mean %CV < 7.5. The mean interday precision for all standards was < 10% of the expected concentration. Excellent linear responses were observed with coefficients of > 0.9999. Good compositional data could be obtained from the analysis of derivatized protein hydrolysates containing as little as 50.5 ng of sample. Therefore, the facile BCEOC derivatization coupled with mass spectrometry allowed the development of a highly sensitive and specific method for the quantitative analysis of trace levels of amino acids and peptides from biological and natural environmental samples. (c) 2005 Elsevier B.V. All rights reserved.