排序方式: 共有41条查询结果,搜索用时 15 毫秒
1.
Natalini B Marinozzi M Sardella R Macchiarulo A Pellicciari R 《Journal of chromatography. A》2004,1033(2):363-367
The chromatographic resolution of enantiomeric amino acids is accomplished on a reversed phase column using aqueous mobile phase containing the chiral reagent N,N-dimethyl-S-phenylalanine-Cu(II). The separation is a result of the whole interaction between the diastereomeric complex surface and the mixed stationary phase realized by the dynamic coating of the RP-18 carbon chains layer. The elution order seems to be related to the different water coordination capability on copper ion in the formation of the mixed ternary complexes. 相似文献
2.
B. Natalini R. Sardella E. Camaioni S. Natalini R. Pellicciari 《Chromatographia》2006,64(5-6):343-349
With the aim of optimizing the chromatographic process by avoiding any preliminary derivatizing step, we examined the chromatographic behaviour of a selected set of unconjugated bile acids looking at the dominant factors that affect the performances of three different stationary phases: RP-8, RP-18 and RP-18 Base Deactivated (RP-18-BD). Accordingly to its structural peculiarity, the RP-18-BD column combined with a specific mobile phase has proved to be the most suitable one, in enhancing both separation factor α and resolution R
S
within the selected set of analytes. Pronounced changes in the chromatographic profiles by only slightly changing the mobile phase composition (pH, buffer concentration, percentage and kind of organic modifier) prompted us to achieve satisfactory results in the separation and resolution of the selected set of bile acids.Presented at: CE in the Biotechnology & Pharmaceutical Industries: 7th symposium on the practical applications for the analysis of proteins, nucleotides and small molecules, Montreal, Canada, August 12–16, 2005.An erratum to this article can be found at 相似文献
3.
Sardella R. Ianni F. Pucciarini L. Marinozzi M. Zlotskii S. S. Natalini B. 《Russian Journal of General Chemistry》2017,87(5):1079-1084
Russian Journal of General Chemistry - In the scope of a broader study focused on glutamate receptors regulators, we have been engaged in synthesis, analysis and pharmacological characterization of... 相似文献
4.
J. Barba-Ortega Edson Sardella J. Albino Aguiar 《Physica C: Superconductivity and its Applications》2010,470(21):1964-1967
Nonlinear time-dependent Ginzburg–Landau (TDGL) equations were solved in the present work using the link variables method. Vortex configurations were investigated in a superconducting circular sector immersed in an external magnetic field applied perpendicular to its plane. Magnetization and free energy were calculated as a function of the applied magnetic field at several temperatures. This paper illustrates how the vortices moved around at the transition fields before they become accommodated into an equilibrium configuration. A linear dependence of the magnetization dependence on temperature has been found for a certain magnetic field. 相似文献
5.
Natalini B Sardella R Macchiarulo A Natalini S Pellicciari R 《Journal of separation science》2007,30(1):21-27
A dynamic coating of the RP-18 carbon chain layers with the new chiral selector (S)-(-)-alpha,alpha-di(2-naphthyl)-2-pyrrolidinemethanol allowed the formation of a mixed chiral stationary phase that has been used in the separation of a selected set of amino acid racemates. Both a representative model and classification structure-property relationship studies have been performed in order to study the contribution of hydrophobic, bulky and electron-donating groups in the side chain of the chiral selector to the mechanism of chiral recognition. 相似文献
6.
Natalini B Sardella R Camaioni E Gioiello A Pellicciari R 《Analytical and bioanalytical chemistry》2007,388(8):1681-1688
The discovery that bile acids are involved in the modulation of nuclear steroid receptors has prompted renewed interest in
this field of research. Due to the nature of research in this field, a technique that enables simple and effective assessment
of the hydrophobic/hydrophilic balance, thus improving and speeding up evaluations of the biological profiles of these compounds,
is greatly needed. In this context, both CMC value determination and RP-HPLC mobility evaluation were explored as possible
approaches. While the CMC was calculated using the noninvasive conductimetric method, the RP-HPLC mobility was assessed by
measuring the retention factor at several mobile phase compositions and extrapolating back to the pure aqueous mobile phase.
The correlation of the CMC with the derived chromatographic hydrophobic index ϕ
0 was satisfactory.
Figure Experimental versus predicted pCMC values 相似文献
7.
We studied the resistive state of a mesoscopic superconducting strip (bridge) at zero external applied magnetic field under a transport electric current, , subjected to different types of boundary conditions. The current is applied through a metallic contact (electrode) and the boundary conditions are simulated via the deGennes extrapolation length b. It will be shown that the characteristic current–voltage curve follows a scaling law for different values of b. We also show that the value of at which the first vortex–antivortex (V–Av) pair penetrates the sample, as well as their average velocities and dynamics, strongly depend on the b values. Our investigation was carried out by solving the two-dimensional generalized time dependent Ginzburg–Landau (GTDGL) equation. 相似文献
8.
Venturoni F Gioiello A Sardella R Natalini B Pellicciari R 《Organic & biomolecular chemistry》2012,10(20):4109-4115
A multi-gram scale protocol for the N-acyl amidation of bile acids with glycine and taurine has been successfully developed under continuous flow processing conditions. Selecting ursodeoxycholic acid (UDCA) as the model compound and N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) as the condensing agent, a modular mesoreactor assisted flow set-up was employed to significantly speed up the optimization of the reaction conditions and the flow scale-up synthesis. The results in terms of yield, in line purification, analysis, and implemented flow set-up for the reaction optimization and large scale production are reported and discussed. 相似文献
9.
10.
Benedetto Natalini Roccaldo Sardella Nicola Giacchè Samantha Palmiotto Emidio Camaioni Maura Marinozzi Antonio Macchiarulo Roberto Pellicciari 《Analytical and bioanalytical chemistry》2010,397(5):1997-2011
Owing to their chelation ability, a series of fully constrained l-Glu analogs formed by the spiro-union of two cyclopropane rings (1-aminospiro[2.2]pentyl-1,4-dicarboxylic acids, ASPED A–D),
was submitted to chiral ligand-exchange chromatographic (CLEC) analysis. As the initial step, two methodologically different
chiral devices were evaluated. A chiral stationary phase (CSP) obtained by dynamic coating of C18 chains with the S-trityl-(R)-cysteine ((R)-STC) was used first with this objective. The lack of separation of the enantiomers of ASPED C and D prompted us to utilize
the chiral mobile phase (CMP) prepared from O-benzyl-(S)-serine ((S)-OBS). The latter afforded complete separation of the four pairs of enantiomers. For all the pairs, quantum mechanical investigations
shed light on the main features responsible for the different enantiomer recognition mechanism with (S)-OBS. The validated analytical method was then fruitfully adopted for semi-preparative-scale isolation of the enantiomers
of ASPED C. 相似文献