Simulated Moving-bed Adsorption For Separation Of Racemic Mixtures

The two enantiomers that constitute a racemate have different activities when employed as pharmaceuticals. Due to this fact, fully recognized today, the pharmaceutical industry has been forced to market pure enantiomers instead of the racemic mixture whenever a chiral compound is involved. The simulated moving bed (SMB) is a chromatographic process that, unlike traditional HPLC systems, operates continuously without losing the enantiomeric purity of the outlet streams. The present work describes the enantioseparation of the anesthetic ketamine in a semipreparative-scale SMB unit. The chiral stationary phase employed was the microcrystalline cellulose triacetate. The outlet streams were analyzed by an on-line system, composed by an UV/VIS meter and a polarimeter, and also by HPLC. The analysis indicated purity values up to 100% for the stream of interest and up to 97.7% for the other stream.211127136Blaschke, G., Chromatographic resolution of chiral drugs on polyamides and cellulose triacetate (1986) Journal of Liquid Chromatography, 9 (2), pp. 341-368Cass, Q.B., Degani, A.L.G., Tiritan, E., Matlin, S.E., Curran, D.P., Balog, A., Enantiomeric resolution by HPLC of axial chiral amides using amylose tris((S)-1-phenylethylcarbamate) (1997) Chirality, 9, pp. 109-112Francotte, E.R., Wolf, R.M., Lohmann, D., Muller, R., Chromatographic resolution of racemates on chiral stationary phases. I. Influence of the supramolecular structure of cellulose triacetate (1985) Journal of Chromatography, 345, pp. 25-37Juza, M., Mazzotti, M., Morbidelli, M., Simulated moving bed and its application to chiraltechnology (2000) Trends in Biotechnology, 18, pp. 108-118Lodevico, R.G., Bobbit, D.R., Edkins, T.J., Determination of enantiomeric excess using a chiral selective separation mode and polarimetric detection (1997) Talanta, 44, pp. 1353-1363Mazzotti, M., Storti, G., Morbidelli, M., Optimal operation of simulated moving beds for nonlinear chromatographic separations (1997) Journal of Chromatography A, 769, pp. 3-24McCoy, M., SMB emerges as a chiral technique (2000) Chemical and Engineering News, 78 (25), pp. 1-3Nicoud, R.M., A packing procedure for high flow rate and high stability columns using cellulose triacetate (1993) LC - GC Int., 6, pp. 636-637Nicoud, R.M., The separation of optical isomers by simulated moving bed chromatography (Part II) (1999) Pharmaceutical Technology Europe, 11, pp. 28-34Pedeferri, M.P., Zenoni, G., Mazzotti, M., Morbidelli, M., Experimental analysis of a chiral separation through simulated moving bed chromatography (1999) Chemical Engineering Science, 54, pp. 3735-374

Inclusive cross section and double helicity asymmetry for \pi^0 production in p+p collisions at sqrt(s)=200 GeV: Implications for the polarized gluon distribution in the proton

The PHENIX experiment presents results from the RHIC 2005 run with polarized proton collisions at sqrt(s)=200 GeV, for inclusive \pi^0 production at mid-rapidity. Unpolarized cross section results are given for transverse momenta p_T=0.5 to 20 GeV/c, extending the range of published data to both lower and higher p_T. The cross section is described well for p_T < 1 GeV/c by an exponential in p_T, and, for p_T > 2 GeV/c, by perturbative QCD. Double helicity asymmetries A_LL are presented based on a factor of five improvement in uncertainties as compared to previously published results, due to both an improved beam polarization of 50%, and to higher integrated luminosity. These measurements are sensitive to the gluon polarization in the proton, and exclude maximal values for the gluon polarization.Comment: 375 authors, 7 pages, 3 figures. Submitted to Phys. Rev. D, Rapid Communications. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

System Size and Energy Dependence of Jet-Induced Hadron Pair Correlation Shapes in Cu+Cu and Au+Au Collisions at sqrt(s_NN) = 200 and 62.4 GeV

We present azimuthal angle correlations of intermediate transverse momentum (1-4 GeV/c) hadrons from {dijets} in Cu+Cu and Au+Au collisions at sqrt(s_NN) = 62.4 and 200 GeV. The away-side dijet induced azimuthal correlation is broadened, non-Gaussian, and peaked away from \Delta\phi=\pi in central and semi-central collisions in all the systems. The broadening and peak location are found to depend upon the number of participants in the collision, but not on the collision energy or beam nuclei. These results are consistent with sound or shock wave models, but pose challenges to Cherenkov gluon radiation models.Comment: 464 authors from 60 institutions, 6 pages, 3 figures, 2 tables. Submitted to Physical Review Letters. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

Measurement of Bottom versus Charm as a Function of Transverse Momentum with Electron-Hadron Correlations in p+p Collisions at sqrt(s)=200 GeV

The momentum distribution of electrons from semi-leptonic decays of charm and bottom for mid-rapidity |y|<0.35 in p+p collisions at sqrt(s)=200 GeV is measured by the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) over the transverse momentum range 2 < p_T < 7 GeV/c. The ratio of the yield of electrons from bottom to that from charm is presented. The ratio is determined using partial D/D^bar --> e^{+/-} K^{-/+} X (K unidentified) reconstruction. It is found that the yield of electrons from bottom becomes significant above 4 GeV/c in p_T. A fixed-order-plus-next-to-leading-log (FONLL) perturbative quantum chromodynamics (pQCD) calculation agrees with the data within the theoretical and experimental uncertainties. The extracted total bottom production cross section at this energy is \sigma_{b\b^bar}= 3.2 ^{+1.2}_{-1.1}(stat) ^{+1.4}_{-1.3}(syst) micro b.Comment: 432 authors, 6 pages text, 3 figures. Submitted to Phys. Rev. Lett. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm