bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantification of fexofenadine in human plasma by liquid chromatography coupled to electrospray tandem mass spectrometry using mosapride as internal standard
Authors: Nirogi Ramakrishna V. S. , Kandikere Vishwottam N. , Shukla Manoj , Mudigonda Koteshwara , Maurya Santosh , Komarneni Prashanth 
Published: January 2007

AbstractA rapid high‐performance liquid chromatography/positive ion electrospray tandem mass spectrometry method was developed and validated for the quantification of fexofenadine in human plasma using mosapride as internal standard. Following solid‐phase extraction, the analytes were separated using an isocratic mobile phase on a reverse‐phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective [M+H]+ions,m/z502/466 for fexofenadine andm/z422/198 for the IS. The method exhibited a linear dynamic range of 1–500 ng/mL for fexofenadine in human plasma. The lower limit of quantification was 1 ng/mL with a relative standard deviation of less than 5% for fexofenadine. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. The total chromatographic run time of 2 min for each sample made it possible to analyze more than 400 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability or bioequivalence studies. Copyright © 2007 John Wiley & Sons, Ltd.
Determination of N‐methyl‐4‐isoleucine‐cyclosporin (NIM811) in human whole blood by high performance liquid chromatography‐tandem mass spectrometry
Authors: Li Wenkui , Luo Suyi , Hayes Michael , He Handan , Tse Francis L. S. 
Published: January 2007

AbstractA liquid chromatographic method with tandem mass spectrometric detection (LC‐MS/MS) for the determination of N‐methyl‐4‐isoleucine‐cyclosporin (NIM811) was developed and validated over the concentration range 1–2500 ng/mL in human whole blood using a 0.05 mL sample volume. NIM811 and the internal standard, d12‐cyclosporin A (d12‐CsA), were extracted from blood using MTBE via liquid–liquid extraction. After evaporation of the organic solvent and reconstitution, a 10 µL aliquot of the resulting extract was injected onto the LC‐MS/MS system. Chromatographic separation of NIM811 and internal standard was performed using a Waters Symmetry RP‐8 (50 × 4.6 mm, 3 µm particle size) column. The mobile phase consists of 10 mm ammonium acetate in water (A) and acetonitrile (B), with 45% B from 0 to 0.2 min, 45 to 85% B from 0.2 to 0.8 min and 85% B from 0.8 to 2.2 min. The total run time was 3.5 min with a flow rate of 0.8 mL/min. The method was validated for sensitivity, linearity, reproducibility, stability, dilution integrity and recovery. The precision and accuracy of quality control samples at low (2.00 ng/mL), medium (20.0 and 400 ng/mL) and high (2000 ng/mL) concentrations were in the range 1.1–4.3% relative standard deviation (RSD) and −2.5–10.0% (bias), respectively, from three validation runs. The method has been used to measure the exposure of NIM811 in human subjects. Copyright © 2007 John Wiley & Sons, Ltd.
Determination of gambogic acid in dog plasma by high‐performance liquid chromatography for a pharmacokinetic study
Authors: Hao Kun , Zhao Xiao‐Ping , Liu Xiao‐Quan , Wang Guang‐Ji 
Published: January 2007

AbstractA rapid, simple and sensitive high‐performance liquid chromatography method for the quantification of gambogic acid in dog plasma was developed and validated. After acidification with hydrochloric acid, dog plasma was extracted with ethyl acetate and determined by HPLC. The analysis was carried out on a reversed‐phase C18 analytical column. The mobile phase consisted of a mixture of methanol–0.05% phosphoric acid (94:6, v/v), and the column temperature was maintained at 35°C. A constant mobile phase flow rate of 1.0 mL/min was employed throughout the analyses. The ultraviolet detector was set at 360 nm. Chromatographic separation was achieved in less than 10 min and the calibration curve was linear over a concentration range of 0.156–20 µg/mL. The intra‐assay and inter‐assay variability values were less than 10.0%. The accuracy ranged from 93.0 to 104.2%. The established method has been successfully applied to a pharmacokinetic study of gambogic acid in dogs. Copyright © 2007 John Wiley & Sons, Ltd.
A liquid chromatography–mass spectrometry assay method for simultaneous determination of amiodarone and desethylamiodarone in rat specimens
Authors: Shayeganpour Anooshirvan , Somayaji Vishwa , Brocks Dion R. 
Published: January 2007

AbstractA liquid chromatographic‐mass spectrometry (LC/MS) assay method was developed for the determination of amiodarone and desethylamiodarone in rat specimens. Analytes were extracted using liquid–liquid extraction in hexane. The LC/MS system consisted of a Waters Micromass ZQ™ 4000 spectrometer with an autosampler and pump. A C18 3.5 µm (2.1 × 50 mm) column heated to 45°C was used for separation. The mobile phase consisted of methanol and 0.2% aqueous formic acid pumped at 0.2 mL/min as a linear gradient. Components eluted within 12 min. The concentrations of ethopropazine (internal standard), desethylamiodarone and amiodarone were monitored for m/z of 313.10, combination of 546.9 and 617.73, and 645.83, respectively. In plasma (0.1 mL), linearity was achieved between the peak area ratios and concentrations over the range of 2.5–1000 ng/mL for both amiodarone and desethylamiodarone (r2 > 0.999). The intraday and interday CV were equal or less than 18%, and mean error was <12%. Similarly, in homogenates containing 0.1 g of rat tissue, linearity was observed in standards ranging from 5 to 5000 ng/g. The method was successfully used to measure tissue and plasma concentrations of drug. The validated lower limit of quantitation was 2.5 ng/mL for drug and metabolite, based on 0.1 mL of plasma. Copyright © 2007 John Wiley & Sons, Ltd.
The lipophilicity estimation of 5‐arylidene derivatives of (2‐thio)hydantoin with antimycobacterial activity
Authors: Łażewska Dorota , Maludziński Piotr , Szymańska Ewa , Kieć‐Kononowicz Katarzyna 
Published: January 2007

AbstractThe lipophilicity of antituberculotic 5‐arylidene derivatives of (thio)hydantoin, thioacetazone and isoniazid has been determined by reversed‐phase thin‐layer chromatography (RP‐TLC). Mixtures of acetone and water (with acetone content 60–85%) were used as the mobile phase. The RM (relative lipophilicity) of each compound (except isoniazid) decreased linearly with the increasing concentration of acetone. The partition coefficients (log P) of the compounds were calculated by the use of eight computer programs (ClogP, KowWin, XlogP, AlogPs, CAChe, Pallas, Interactive analysis and Slipper) and compared with the experimental lipophilicity (RM0). According to the observations the best tools for in silico predicting log P of (2‐thio)hydantoins are programs KowWin and AlogPs. Copyright © 2007 John Wiley & Sons, Ltd.
Determination of secnidazole in human plasma by high‐performance liquid chromatography with UV detection and its application to the bioequivalence studies
Authors: Li Xiaoyu , Sun Jianguo , Wang Guangji , Zheng Yuanting , Yan Bei , Xie Haitang , Gu Yi , Ren Hongchan 
Published: January 2007

AbstractA simple, accurate, precise and sensitive HPLC‐UV method was developed for the determination of secnidazole in human plasma. Secnidazole and tinidazole (IS) were extracted from 0.2 mL of human plasma by ethyl acetate. Secnidazole was then separated by HPLC on a Diamond C18 column and quantified by ultraviolet detection at 319 nm. The mobile phase consisted of acetonitrile–aqueous 5 mm sodium acetate (30:70, v/v) containing of 0.1% acetic acid adjusted to pH 4.0, and the flow rate was 1.0 mL/min. The low limit of quantification was 0.1 µg/mL. The method was linear over the concentration range 0.1–25.0 µg/mL (R2 = 1.000). The recovery of secnidazole from human plasma ranged from 76.5 to 89.1%. Inter‐ and intra‐assay precision ranged from 3.3 to 10.7%. Secnidazole in plasma was stable when stored at ambient temperature for 8 h, at −20°C for 2 weeks and at −20°C for three freeze–thaw cycles. The developed method was successfully applied to the pharmacokinetic and bioequivalence studies between test and reference secnidazole tablets following a single 500 mg oral dosage to 20 healthy volunteers of both genders. Pharmacokinetics parameters Tmax, Cmax, AUC0−t, AUC0−∞, T1/2 were determined of both preparations. The analysis of variance (ANOVA) did not show any significant difference between the two preparations and 90% confidence intervals fell within the acceptable range for bioequivalence. It was concluded that the two secnidazole preparations are bioequivalence and may be used interchangeably. Copyright © 2007 John Wiley & Sons, Ltd.
Determination of paclitaxel in human and rat blood samples after administration of low dose paclitaxel by HPLC‐UV detection
Authors: Yonemoto Haruo , Ogino Seiko , Nakashima Mihoko N. , Wada Mitsuhiro , Nakashima Kenichiro 
Published: January 2007

AbstractA simple and sensitive HPLC‐UV method was developed for the determination of paclitaxel (TXL) in human and rat blood samples. 4‐Hydroxybenzoic acid n‐hexyl ester was used as an internal standard. TXL was extracted by a liquid–liquid extraction with tert‐butylmethyl ether. The disturbing peaks in the case of serum sample were removed by pre‐extraction with hexane. The separation of TXL was achieved within 25 min using an ODS column with 50% acetonitrile aqueous solution as a mobile phase at a flow rate of 1.0 mL/min. The eluent was monitored at 230 nm, and the resulted retention times of TXL and IS were 11.2 and 20.4 min. The detection limits of TXL for human plasma, serum and rat plasma samples at a signal‐to‐noise ratio of 3 were 10, 9.5 and 7.5 ng/mL, respectively. The proposed methods were applicable to the determination of TXL in human patients' plasma ranging from 15 to 27 ng/mL. Furthermore, monitoring of the time course of TXL after its single administration to rat could be demonstrated. Copyright © 2007 John Wiley & Sons, Ltd.
Pharmacokinetic study of puerarin in rat serum by liquid chromatography tandem mass spectrometry
Authors: Prasain Jeevan K. , Peng Ning , Acosta Edward , Moore Ray , Arabshahi Alireza , Meezan Elias , Barnes Stephen , Wyss J. Michael 
Published: January 2007

AbstractA highly sensitive and specific atmospheric pressure chemical ionization liquid chromatography–tandem mass spectrometry method was developed for serum pharmacokinetic studies of puerarin in rats. Chromatography was carried out on a reversed‐phase Phenomenex Synergi 4 µm Fusion‐RP80 column (150 × 2.0 mm i.d.) using a mobile phase consisting of acetonitrile–water (10:90, v/v) in 10 mm NH4OAc with a flow rate of 0.2 mL/min. Puerarin was analyzed in the multiple reaction monitoring mode with a precursor/product ion transition of m/z 415/267. The method was demonstrated to be specific and sensitive, and a linear response was observed over a range of 2–5000 ng/mL in rat serum. The validated method was successfully applied to the characterization of the pharmacokinetics of puerarin in rat serum after oral administration to spontaneously hypertensive rats. The blood concentration–time profile of puerarin showed a rapid initial increase, reaching a maximum and then declining within 1 h. Puerarin could not be detected after 24 h. The main pharmacokinetic parameters for puerarin after oral administration were as follows: Cmax (3.54 ± 2.03 mg/L), Tmax (0.68 ± 0.37 h), AUC0−t (7.29 ± 3.79 mg h/L), AUC0−∞ (9.17 ± 4.87 mg h/L), T1/2 (1.7 ± 0.6 h), CL/F (7.24 ± 4.27 L/h/kg) and V/F (17.88 ± 13.55 L/h/kg). Copyright © 2007 John Wiley & Sons, Ltd.
Handling of Rayleigh and Raman scatter for PARAFAC modeling of fluorescence data using interpolation
Authors: Bahram Morteza , Bro Rasmus , Stedmon Colin , Afkhami Abbas 
Published: January 2007

AbstractFluorescence excitation‐emission matrix (EEM) measurements are useful in fields such as food science, analytical chemistry, biochemistry and environmental science. EEMs contain information which can be modeled using the parallel factor analysis (PARAFAC) model but the data analysis is often complicated due to both Rayleigh and Raman scattering. There are several established ways to deal with scattering effects. However, all of these methods have associated problems. This paper develops a new method for handling scattering using interpolation in the areas affected by first‐ and second‐order Rayleigh and Raman scatter in such a way that the interfering signal is, at best, removed. The suggested method is fast and requires no additional input other than specifying the scattering region. The results of the proposed method were compared with those obtained from common alternative approaches used for preprocessing fluorescence data before analysis with PARAFAC and were shown to be equally good for various types of EEM data. The main advantage of the interpolation method is in its lack of additional metaparameters, its algorithmic speed and subsequent speed‐up of PARAFAC modeling. It also allows for using EEM data in software not able to handle missing data. Copyright © 2007 John Wiley & Sons, Ltd.
Exceptional Affinity of Nanostructured Organic–Inorganic Hybrid Materials towards Dioxygen: Confinement Effect of Copper Complexes
Authors: Brandès Stéphane , David Gabriel , Suspène Clément , Corriu Robert J. P. , Guilard Roger 
Published: January 2007

AbstractWe report the exceptional reactivity towards dioxygen of a nanostructured organic–inorganic hybrid material due to the confinement of copper cyclam within a silica matrix. The key step is the metalation reaction of the ligand, which can occur before or after xerogel formation through the sol–gel process. The incorporation of a CuII center into the material after xerogel formation leads to a bridged CuI/CuII mixed‐valence dinuclear species. This complex exhibits a very high affinity towards dioxygen, attributable to auto‐organization of the active species in the solid. The remarkable properties of these copper complexes in the silica matrix demonstrate a high cooperative effect for O2 adsorption; this is induced by close confinement of the two copper ions leading to end‐on μ‐η1:η1‐peroxodicopper(II) complexes. The anisotropic packing of the tetraazamacrocycle in a lamellar structure induces an exceptional reactivity of these copper complexes. We show for the first time that the organic–inorganic environment of copper complexes in a silica matrix fully model the protecting role of protein in metalloenzymes. For the first time an oxygenated dicopper(II) complex can be isolated in a stable form at room temperature, and the reduced Cu2I,I species can be regenerated after several adsorption–desorption cycles. These data also demonstrate that the coordination scheme and reactivity of the copper cyclams within the solid are quite different from that observed in solution.
Reaktionstechnische Untersuchungen zur Umesterung der ionischen Flüssigkeit 1‐Ethyl‐3‐methylimidazoliumethylsulfat ([EMIM][EtOSO3])
Authors: Himmler S. , Hörmann S. , Obert K. , Wasserscheid P. 
Published: January 2007

AbstractIonische Flüssigkeiten (ILs) sind neuartige Lösungsmittel, die auf Grund ihrer interessanten und zum Teil einzigartigen Eigenschaftskombinationen für vielfältige Anwendungen interessante Hilfsstoffe, Betriebsmittel oder Funktionsmaterialien darstellen. Die Tatsache, dass ionische Flüssigkeiten bisher hauptsächlich batchweise bzw. im Labormaßstab hergestellt werden, beschränkt zum einen ihre Verfügbarkeit für den großtechnischen Einsatz und wirkt sich zum anderen unvorteilhaft auf die Produktpreise aus. Am Beispiel der Umesterung der kommerziell im Tonnenmaßstab verfügbaren ionischen Flüssigkeit [EMIM][EtOSO3] mit verschiedenen Alkoholen wird ein Weg aufgezeigt, um kostengünstig unterschiedliche Alkylsulfatschmelzen herzustellen. Zudem wird durch kinetische und thermodynamische Untersuchungen des Reaktionssystems die Basis für eine Weiterentwicklung des Syntheseverfahrens hin zu einer kontinuierlichen Synthese geschaffen.
Thin Films Composed of Multiwalled Carbon Nanotubes, Gold Nanoparticles and Myoglobin for Humidity Detection at Room Temperature
Authors: Qi Zhi‐mei , Wei Mingdeng , Honma Itaru , Zhou Haoshen 
Published: January 2007

AbstractOptically transparent and electrically conductive nanocomposite thin films consisting of multiwalled carbon nanotubes (MWCNTs), gold nanoparticles (GNPs) and myoglobin molecules that glue GNPs and MWCNTs together are fabricated for the first time on glass substrates from aqueous solution. The nanocomposite thin film is capable of varying its resistance, impedance or optical transmittance at room temperature in response to changes in ambient humidity. The conductometric sensitivity to relative humidity (RH) of the nanocomposite thin film is compared with those of the pure and Mb‐functionalized MWCNT layers. The pure MWCNT layer shows a small increase in its resistance with increasing RH due to the effect of p‐type semiconducting nanotubes present in the film. In contrast, a four times higher sensitivity to RH is observed for both the nanocomposite and Mb‐functionalized MWCNT thin films. The sensitivity enhancement is attributable to swelling of the thin films induced by water absorption in the presence of Mb molecules, which increases the inter‐nanotube spacing and thereby causes a further increase of the film resistance. A humidity change as low as ΔRH=0.3 % has been readily detected by conductometry using the nanocomposite thin film.
Geometry Dependence of Spin–Spin Couplings in Cyanamide by DFT Analysis
Authors: van Mourik Tanja , Dingley Andrew J. 
Published: January 2007

AbstractThere have been numerous theoretical and experimental investigations examining NMR parameters related to non‐amino NH⋅⋅⋅N H‐bonded moieties in both biological and chemical contexts. In contrast, little information on the geometry dependence of NMR parameters related to the biologically important H‐bond donor amino group is available. Herein, the geometric dependencies of the one‐bond amino NH spin–spin coupling constants [1J(NH)] in the cyanamide monomer and dimer have been computed with B3LYP and the aug‐cc‐pVTZ‐su0 basis set. In an isolated planar cyanamide molecule, the |1J(NH)| couplings were found to increase as the NH bond lengthened. In contrast, in the planar cyanamide dimer the size of the H‐bonded amino NH coupling (|1J(NdHd)|) decreased with increasing NdHd bond length. The |1J(NdHd)| coupling was larger than the |1J(NdHfree)| coupling for NdHd distances up to 1.18 Å (for a fixed NdHfree distance of 1.006 Å). Hence, the decrease of |1J(NH)| with increasing NH distance, as well as the larger value of |1J(NdHd)| compared to |1J(NdHfree)|, were only observed for situations where the amino group is involved in an H‐bonding interaction. This is attributed to electron redistribution induced by the presence of the second cyanamide molecule. Similar electron‐redistribution effects are thought to be responsible for the observed distance dependence of computed 1J(NH) couplings of H‐bonded amino groups in near‐planar G‐quartet structures. Here, the |1J(NH)| couplings of the amino NH bonds decreased with increasing NH bond length whereas the |1J(NdHd)| couplings are approximately 7 Hz larger than the |1J(NdHfree)| couplings, despite the longer NdHd bond length.
The Active Intermediates of Non‐Heme‐Iron‐Based Systems for Catalytic Alkene Epoxidation with H2O2/CH3COOH
Authors: Duban Eduard A. , Bryliakov Konstantin P. , Talsi Evgenii P. 
Published: January 2007

AbstractIron complexes with aminopyridine ligands [FeII(BPMEN)(CH3CN)2](ClO4)2 (1) [BPMEN = N,N′‐dimethyl‐N,N′‐bis(2‐pyridylmethyl)‐1,2‐diaminoethane] and [FeII(TPA)(CH3CN)2](ClO4)2 (2) [TPA = tris(2‐pyridylmethyl)amine] are rare examples of iron‐based catalysts for selective olefin epoxidation with H2O2/CH3COOH combination. Using 1,2H NMR and EPR spectroscopy, it was shown that the active species of the catalytic systems 1/H2O2/CH3COOH and 2/H2O2/CH3COOH are mononuclear iron(IV)‐oxido complexes [(BPMEN)FeIV=O(S)]2+ and [(TPA)FeIV=O(S)]2+, respectively (S = solvent molecule). These intermediates are formed via decomposition of the corresponding acylperoxido complexes [(L)FeIII(O3CCH3)]2+ (L = BPMEN or TPA). The acylperoxido complex [(BPMEN)FeIII(O3CCD3)]2+ was identified in the catalytic system 1/H2O2/CD3COOD by 2H NMR spectroscopy. The improved epoxidation activity and selectivity of the catalytic systems 1/H2O2/CH3COOH and 2/H2O2/CH3COOH, with respect to 1/H2O2 and 2/H2O2, is caused by the effective formation of intermediates [(L)FeIV=O(S)]2+ via decomposition of the acylperoxido complexes [(L)FeIII(O3CCH3)]2+.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Biotrickling filtration of air contaminated with ethanol
Authors: Avalos Ramirez Antonio , Jones J Peter , Heitz Michele 
Published: January 2007

AbstractA biotrickling filter (BTF) for treating high ethanol loads was operated for one year and the effect of operating conditions was studied. The BTF was operated in a range of ethanol inlet concentrations of 0.2–15.0 g m−3 and at three different residence times (30, 65 and 130 s). The experiments show that removal efficiency decreased with increasing ethanol inlet concentration and decreasing air residence time. Removal efficiency varied in the range of 60–100%. A maximum elimination capacity of 970 g m−3 h−1 was obtained for an inlet load of 1610 g m−3 h−1. At a constant residence time, the carbon dioxide (CO2) production rate varied with ethanol inlet concentration. BTF presented the maximum CO2 production rate in the range of inlet concentration of 3.0–7.0 g m−3. Two strategies for controlling biomass accumulation were applied: one consisted in periodical washing; the other combined periodical washing with nutrient starvation by consuming less water and energy. Both strategies led to maintaining the BTF stable, with high adaptability and reproducibility. Copyright © 2007 Society of Chemical Industry