High-performance liquid chromatographic separation of rolipram, bupivacaine and omeprazole using a tartardiamide-based stationary phase influence of flow rate and temperature on the enantioseparation

Chromatographic separation of the chiral drugs rolipram, bupivacaine and omeprazole on a tartardiamide-based stationary phase commercially named Kromasil CHI-TBB is shown in this work. The effect of temperature on the chromatographic separation of the chiral drugs using the Kromasil CHI-TBB stationary phase was determined quantitatively so as to contribute toward the design for the racemic mixtures of the named compound by using chiral columns. A decrease in the retention and selectivity factors was observed, when the column temperature increased. Van't Hoff plots provided the thermodynamic data. The variation of the thermodynamic parameters enthalpy and entropy are clearly negative meaning that the separation is enthalpy controlled.     

Synthesis and spectral data of quinoline products obtained by reaction of N‐(4‐pyridinyliden)anilines and N‐benzylidenaniline with 2,2‐dimethoxypropane (kametani reaction)

A study on interaction between N‐(4‐pyridinyliden)anilines 1‐4 and 2,2‐dimethoxypropane under Kametani reaction conditions was realized. According to the GC‐MS analysis of crude reaction, besides the needed 4‐methyl‐2‐(4‐pyridinyl)quinolines 5‐8 , three collateral products: secondary amines 9‐12 , 4‐(2‐methylprop‐1‐enyl)quinolines 13‐16 and 4‐(2‐methoxy‐2‐methylpropyl)quinolines 17‐20 were formed. Unexpected quinolines 13‐16 as well the desired quinolines 5‐8 were isolated and fully characterized. In contrast, a condensation of N‐benzylidenaniline 21 with 2,2‐dimethoxypropane afforded a set of different quinoline products.     

DNA removal on different chromatography supports used for EPO purification by spike studies

Chromatographic techniques are used in the purification step of human recombinant erythropoietin production process to obtain a reliable product with high purity. Anion-exchange chromatography supports have proved high efficient in removing contaminants such as DNA. For that reason, the DNA removal was determined by spike studies, on three anion-exchange chromatographic supports: gel, membrane, and monolithic column, which is used in intermediate purification stage. This study showed that membrane and monolith columns have very good results in the removal of contaminants at this step. Log removal values (LRV) greater than 3.5 were obtained from DNA spike clearance studies. Monolithic column was determined as the best technological proposal, with more than 4 LRV, 7.72?mg DNA per milliliter of adsorbent and 85% protein recovery in nonspike run. The results of this study may be used as a guide in the selection of commercially available chromatography supports for intermediate purification steps in recombinant protein production.     

Charmed and bottom baryons: a variational approach based on heavy quark symmetry

The use of heavy quark symmetry to study bottom and charmed baryons leads to important simplifications of the non-relativistic three body problem, which turns out to be easily solved by a simple variational ansatz. Our simple scheme reproduces previous results (baryon masses, charge and mass radii, …) obtained by solving the Faddeev equations with simple non-relativistic quark–quark potentials, adjusted to the light and heavy–light meson spectra. Wave functions, parameterized in a simple manner, are also given and thus they can be easily used to compute further observables. Our method has been also used to find the predictions for strangeness-less baryons of the SU(2) chirally inspired quark–quark interactions. We find that the one pion exchange term of the chirally inspired interactions leads to relative changes of the Λ_b and Λ_c binding energies as large as 90%.     

Nuclear effects on lepton polarization in charged-current quasielastic neutrino scattering

We use a correlated local Fermi gas (LFG) model, which accounts also for long distance corrections of the RPA type and final-state interactions, to compute the polarization of the final lepton in charged-current quasielastic neutrino scattering. The present model has been successfully used in recent studies of inclusive neutrino nucleus processes and muon capture. We investigate the relevance of nuclear effects in the particular case of τ polarization in tau-neutrino induced reactions for several kinematics of relevance for neutrino oscillation experiments.     

A Contribution to the Study of the Adsorption of s‐Triazine Herbicides on Glassy Carbon Electrodes by Differential‐Capacity Measurements

Measurements of differential capacity vs. potential have been made for a series of s‐triazine herbicides at different concentrations. In all cases the decrease in capacity was independent of the applied potential, so the adsorption is also independent of the potential. From the measurements it can be established that the adsorption follows Langmuir type isotherms. Adsorption constants were obtained for the different herbicides at 25 °C (simetryn, simazine, terburyn and prometon) as well as those to simetryn at different temperatures, from which the adsorption enthalpy of this herbicide was calculated being its value of 17.5 kJ mol^?1.