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Chemical Purity (chemical + purity)
Selected AbstractsRadiosynthesis and in vivo evaluation of [11C]Ro-647312: a novel NR1/2B subtype selective NMDA receptor radioligandJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 13 2004Frédéric Dollé Abstract [2-(3,4-Dihydro-1H-isoquinolin-2-yl)-pyridin-4-yl]-dimethylamine, Ro-647312 (1) represents a new novel class of NR1/2B subtype selective NMDA ligand. Ro-647312 has been radiolabelled with carbon-11 using [11C]methyl triflate from the nor- methyl compound 2. The reaction was performed in acetone as solvent using aqueous NaOH as base. Following HPLC purification [11C]Ro-647312 ([11C]- 1) was obtained in 6.9,9.2% (n = 3) radiochemical yield decay-corrected based on starting [11C]CO2, with specific radioactivity measured at the end of the radiosynthesis ranging from 1.0 to 3.5 Ci/µmol (37,129 GBq/µmol). Radiochemical and chemical purities were assessed as >99 and >95%, respectively. Following i.v. injection of [11C]- 1 in rat, the distribution of radioactivity was homogeneous in all brain structures and did not correlate with the known distribution of NR2B subunits. The radioactivity observed in plasma was also higher than any brain structure throughout the time course of the experiment. [11C]- 1 does not possess the required properties for imaging NMDA receptors using positron emission tomography. Copyright © 2004 John Wiley & Sons, Ltd. [source] Manganese in biogenic magnetite crystals from magnetotactic bacteriaFEMS MICROBIOLOGY LETTERS, Issue 2 2009Carolina N. Keim Abstract Magnetotactic bacteria produce either magnetite (Fe3O4) or greigite (Fe3S4) crystals in cytoplasmic organelles called magnetosomes. Whereas greigite magnetosomes can contain up to 10 atom% copper, magnetite produced by magnetotactic bacteria was considered chemically pure for a long time and this characteristic was used to distinguish between biogenic and abiogenic crystals. Recently, it was shown that magnetosomes containing cobalt could be produced by three strains of Magnetospirillum. Here we show that magnetite crystals produced by uncultured magnetotactic bacteria can incorporate manganese up to 2.8 atom% of the total metal content (Fe+Mn) when manganese chloride is added to microcosms. Thus, chemical purity can no longer be taken as a strict prerequisite to consider magnetite crystals to be of biogenic origin. [source] Probing the Anisotropic Field-Effect Mobility of Solution-Deposited Dicyclohexyl-,-quaterthiophene Single Crystals,ADVANCED FUNCTIONAL MATERIALS, Issue 10 2007Abstract Measuring the anisotropy of the field-effect mobility provides insight into the correlation between molecular packing and charge transport in organic semiconductor materials. Single-crystal field-effect transistors are ideal tools to study intrinsic charge transport because of their high crystalline order and chemical purity. The anisotropy of the field effect mobility in organic single crystals has previously been studied by lamination of macroscopically large single crystals onto device substrates. Here, a technique is presented that allows probing of the mobility anisotropy even though only small crystals are available. Crystals of a soluble oligothiophene derivative are grown in bromobenzene and drop-cast onto substrates containing arrays of bottom-contact gold electrodes. Mobility anisotropy curves are recorded by measuring numerous single crystal transistor devices. Surprisingly, two mobility maxima occur at azimuths corresponding to both axes of the rectangular cyclohexyl-substituted quaterthiophene (CH4T) in-plane unit cell, in contrast to the expected tensorial behavior of the field effect mobility. [source] Synthesis and radiolabelling of Re(CO)3 - , -elemene derivatives as potential therapeutic radiopharmaceuticalsJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 5 2009Yunfeng Ren Abstract , -Elemene, (1S, 2S, 4R)-(,)-(1-methy-1-vinyl-2,4-diisopropenyl cyclohexane) is an anticancer agent from the Traditional Chinese Herb Medicinal. Three novel Re(CO)3 - , -elemene derivatives including their radioactive conjugates containing N,N,N tridentate ligands and tricarbonyl rhenium (complex 12, 13, 14) were synthesized. Their structures were characterized by infrared (IR), 1H-NMR and HRMS. Good radioactive yield (above 90%) and radioactive chemical purity with Re-188 (above 95%) were obtained for all of the three derivatives (complex 15, 16, 17). The antiproliferative activity of non-radioactive , -elemene-Re(CO)3 derivatives on Lewis lung cancer cells and HeLa cell lines were evaluated by WST-1 methods. The result shows substantial decrease in IC50 values compared with the parent compound , -elemene. The synthesis and radiosynthesis of , -elemene tricarbonyl rhenium conjugates provide the possibility to find a new kind of potential radiopharmaceuticals on , -elemene. Copyright © 2009 John Wiley & Sons, Ltd. [source] Automated radiosynthesis of [18F]SPA-RQ for imaging human brain NK1 receptors with PETJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 1 2006Frederick T. Chin Abstract [18F]SPA-RQ is an effective radioligand for imaging brain neurokinin type-1 (NK1) receptors in clinical research and drug discovery with positron emission tomography. For the automated regular production of [18F]SPA-RQ for clinical use in the USA under an IND we chose to use a modified commercial synthesis module (TRACERlab FXF-N; GE Medical Systems) with an auxiliary custom-made robotic cooling,heating reactor, after evaluating several alternative radiosynthesis conditions. The automated radiosynthesis and its quality control are described here. [18F]SPA-RQ was regularly obtained within 150 min from the start of radiosynthesis in high radiochemical purity (>99%) and chemical purity and with an overall decay-corrected radiochemical yield of 15±2% (mean±S.D.; n=10) from cyclotron-produced [18F]fluoride ion. The specific radioactivity of [18F]SPA-RQ at the end of synthesis ranged from 644 to 2140 mCi/µmol (23.8,79.2 GBq/µmol). Copyright © 2005 John Wiley & Sons, Ltd. [source] Synthesis of 2-[(2-chloro-2,-[18F]fluoroethyl)amino]-2H-1,3,2-oxazaphosphorinane-2-oxide (18F-fluorocyclophosphamide), a potential tracer for breast tumor prognostic imaging with PETJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 9 2005Goran Lacan Abstract A fluorine-18 labeled analog of the widely used chemotherapeutic agent cyclophosphamide was synthesized as a tracer for prognostic imaging with positron emission tomography. 2-[(2-Chloro-2,-[18F]fluoroethyl)amino]-2H-1,3,2-oxazaphosphorinane-2-oxide (18F-fluorocyclophosphamide), was prepared by direct halogen exchange reaction from the parent cyclophosphamide. In small-scale syntheses, radiochemical yields of up to 4.9% and specific activities of 960 Ci/mmol were achieved in a total synthesis time of 60,75 min. The [18F]-labeled cyclophosphamide analog with radioactive purity >99% and chemical purity >96% was suitable for in vivo (microPET imaging) and ex vivo studies of a murine model of human breast tumors. Copyright © 2005 John Wiley & Sons, Ltd. [source] Regioselective F-18 radiolabeling of AM694, a CB1 cannabinoid receptor ligandJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 9 2003Peter G. Willis Abstract [18F]AM694, [1-(5-[18F]fluoropentyl)-1H-indol-3-yl]-(2-iodophenyl)methanone, 1b, a potential radiotracer for imaging of cerebral cannabinoid receptor (CB1), has been synthesized by no-carrier-added regioselective radiofluorination of the corresponding tosylate. [18F]AM694 was obtained in 20% radiochemical yield (non-decay-corrected) with a specific activity of 14 500 mCi/µmol, a radiochemical purity of > 99%, and a chemical purity of 95.5%. Copyright © 2003 John Wiley & Sons, Ltd. [source] Hydrothermal Synthesis of Alpha Alumina (,-Al2O3) Powders: Study of the Processing Variables and Growth MechanismsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2010Wojciech L. Suchanek Alpha alumina (,-Al2O3) powders and ,-Al2O3/boehmite (,-AlOOH) mixtures with controlled ,-AlOOH contents were synthesized hydrothermally under alkaline or acidic conditions at 380°,435°C for 1,10 days, under 6.9,14.5 MPa pressure, from concentrated precursors without stirring. The precursors were formed by mixing different types of aluminum hydroxides with water, and optionally with ,-Al2O3 seeds, hydrogen peroxide, sulfuric acid, dopants (i.e., KMnO4), and/or other additives. The experiments were performed on industrial scale in large production autoclaves. The synthesized ,-Al2O3 powders exhibited up to 100% phase purity, 99.98% chemical purity, equiaxed morphology, low aggregation levels, narrow crystallite size distributions with primary particle sizes ranging between 100 nm and 40 ,m, and high reproducibility. Precursor types, seeds, chemical additives, and temperature/time of the hydrothermal synthesis were found to govern properties of the powders. Different growth mechanisms for nanosized and rough powders are discussed. Results of this study enable the use of hydrothermal ,-Al2O3 powders in a multitude of applications, and make their hydrothermal production a commercial reality. [source] | ||||||||||