bluuebunny/crossref_metadata_2025_split huggingface dataset:
Separation and HPLC analysis of 15 benzodiazepines in human plasma
Authors: Mercolini Laura , Mandrioli Roberto , Amore Mario , Raggi Maria Augusta 
Published: August 2008

AbstractBenzodiazepines (BZDs) are often prescribed to schizophrenic or depressed patients, as a part of polypharmacy regimens. An HPLC method has been developed for the simultaneous determination of 15 BZDs in human plasma. Separation was obtained by using a C8 RP column and a mobile phase composed of 65% aqueous phosphate buffer at pH 3.0 and 35% ACN. The UV detector was set at 220 nm and clomipramine was used as the internal standard. A careful pretreatment procedure of plasma samples was developed, using SPE with C1 cartridges, which gives high extraction yields (> 97%). The LOQs were always lower than 7.6 ng/mL and the LODs always lower than 2.6 ng/mL for all analytes. The method was successfully applied to plasma samples from depressed and schizophrenic patients undergoing polypharmacy with one or more BZDs. Precision data, as well as accuracy results, were satisfactory and no interference from other drugs was found. Hence, the method seems to be suitable for the therapeutic drug monitoring (TDM) of patients undergoing therapy with one or more BZDs.
Identification of RFLP G6PD mutations by using microcapillary electrophoretic chips (ExperionTM)
Authors: Minucci Angelo , Delibato Elisabetta , Castagnola Massimo , Concolino Paola , Ameglio Franco , Zuppi Cecilia , Giardina Bruno , Capoluongo Ettore 
Published: August 2008

AbstractGlucose‐6‐phosphate dehydrogenase (G6PD) deficiency is one of the most well‐known human genetic defects, identified in more than 400 million individuals in the world. To date, no commercial kits are available for the mutation screening of this disease. Seventy G6PD‐deficient Italian individuals admitted to the Laboratory of Clinical Molecular Biology of Hospital “Agostino Gemelli” of Rome were screened for the most frequent Italian mutations, by means of allele‐specific PCR, followed by restriction fragment length electrophoresis. The present study compares two techniques for the identification of restriction patterns: agarose gel electrophoresis versus Experion system. When the first screening was negative, the entire G6PD gene was sequenced using the ABI 3100 Avant Instrumentation. The G6PD variants identified and their frequencies were the following: G6PD Mediterranean (75.7%), G6PD Seattle (7.1%), G6PD A– 202 + 376 (7.1%), and G6PD Cassano (2.8%). In addition, we identified by direct sequencing two new mutations, namely Buenos Aires and Rignano. With the Experion method, the size band determination was more accurate than that obtained by gel electrophoresis. The Experion system resulted as a valid, easy, and reproducible diagnostic method for the screening of G6PD mutation as compared with the agarose electrophoretic analysis.
Proteome analysis of human dorsolateral prefrontal cortex using shotgun mass spectrometry
Authors: Martins‐de‐Souza Daniel , Gattaz Wagner F. , Schmitt Andrea , Rewerts Christiane , Maccarrone Giuseppina , Dias‐Neto Emmanuel , Turck Christoph W. 
Published: August 2008

AbstractThe prefrontal cortex executes important functions such as differentiation of conflicting thoughts, correct social behavior and personality expression, and is directly implicated in different neurodegenerative diseases. We performed a shotgun proteome analysis that included IEF fractionation, RP‐LC, and MALDI‐TOF/TOF mass spectrometric analysis of tryptic digests from a pool of seven human dorsolateral prefrontal cortex protein extracts. In this report, we present a catalog of 387 proteins expressed in these samples, identified by two or more peptides and high confidence search scores. These proteins are involved in different biological processes such as cell growth and/or maintenance, metabolism/energy pathways, cell communication/signal transduction, protein metabolism, transport, regulation of nucleobase, nucleoside, nucleotide and nucleic acid metabolism, and immune response. This analysis contributes to the knowledge of the human brain proteome by adding sample diversity and protein expression data from an alternative technical approach. It will also aid comparative studies of different brain areas and medical conditions, with future applications in basic and clinical research.
Determination of acid–base dissociation constants of azahelicenes by capillary zone electrophoresis
Authors: Ehala Sille , Míšek Jiří , Stará Irena G. , Starý Ivo , Kašička Václav 
Published: August 2008

AbstractCZE was employed to determine acid–base dissociation constants (pKa) of ionogenic groups of azahelicenes in methanol (MeOH). Azahelicenes are unique 3‐D aromatic systems, which consist of ortho‐fused benzene/pyridine units and exhibit helical chirality. The pKa values of pyridinium groups of the studied azahelicenes were determined from the dependence of their effective electrophoretic mobility on pH by a nonlinear regression analysis. The effective mobilities of azahelicenes were determined by CZE at pH range between 2.1 and 10.5. Thermodynamic pKa values of monobasic 1‐aza[6]helicene and 2‐aza[6]helicene in MeOH were determined to be 4.94 ± 0.05 and 5.68 ± 0.05, respectively, and pKa values of dibasic 1,14‐diaza[5]helicene were found to be equal to 7.56 ± 0.38 and 8.85 ± 0.26. From these values, the aqueous pKa of these compounds was estimated.
Preparation of a high‐performance multi‐lectin affinity chromatography (HP‐M‐LAC) adsorbent for the analysis of human plasma glycoproteins
Authors: Kullolli Majlinda , Hancock William S. , Hincapie Marina 
Published: August 2008

AbstractWe report on the preparation of an improved multi‐lectin affinity support for HPLC separations. We combined the selectivity of three different lectins: concanavalin A (ConA), wheat germ agglutinin (WGA), and jacalin (JAC). Each lectin was first covalently immobilized onto a polymeric matrix and then the three lectin media were combined in equal ratios. The beads were packed into a column to produce a mixed‐bed multi‐lectin HPLC column (high‐performance multi‐lectin affinity chromatography (HP‐M‐LAC)) for fast chromatographic affinity separations. The support was characterized with respect to kinetics of immobilization, ligand density, and binding capacity for human plasma glycoproteins. A high lectin density (15 mg/mL of beads) was found to be optimal for the binding of glycoproteins from human plasma. A single clinical sample can be fractionated in less than 10 min per run, making this a useful sample preparation tool for proteomics/glycoproteomics studies associated with disease abormalities.
Characterization of biodiesel and biodiesel blends using comprehensive two‐dimensional gas chromatography
Authors: Tiyapongpattana Warawut , Wilairat Prapin , Marriott Philip J. 
Published: August 2008

AbstractIn this work the development of a comprehensive 2‐D GC flame ionization detection (GC×GC FID) method for biodiesel fuels is reported. This method is used for the analysis of fatty acid methyl esters (FAMEs) in both biodiesel (B100) and biodiesel blend (B5) samples. The separation of FAME was based on component boiling point in the first dimension and polarity in the second dimension by using a BPX5/BP20 column set to provide a measure of ‘orthogonality’ in the 2‐D space. Here the columns are coupled with a cryogenic modulator operating in a novel temperature programmed mode (TM) whereby the cryotrap is progressively incremented in temperature as the oven temperature is increased. The final method employs eight cryotrap temperature settings. The developed GC×GC method is able to successfully characterize and identify both B100 and B5 FAME components, which are produced from a variety of vegetable oils, animal fats and waste cooking oils, with high precision. The method is capable of analysing FAME with carbon numbers C4–C24, and is particularly suitable to characterize various types of biodiesel, making it possible to differentiate the origin and type of FAME used in the biodiesel samples.
Liposome electrokinetic capillary chromatography in the study of analyte–phospholipid membrane interactions. Application to pesticides and related compounds
Authors: Wiedmer Susanne K. , Kulovesi Pipsa , Riekkola Marja‐Liisa 
Published: August 2008

AbstractInteractions between low‐molar mass analytes and phospholipid membranes were studied by liposome electrokinetic capillary chromatography (LEKC). The analytes were pesticides, some degradation products, and compounds associated with the manufacture of pesticides. Negatively charged liposome dispersions with different zwitterionic lipids (PC) were applied to the determination of retention factors (k) of 15 charged and uncharged compounds. The liposome dispersions consisted of 80:20 mol% of 1,2‐dilauroyl‐sn‐glycero‐3‐phosphocholine (DLPC)/1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phospho‐L‐serine (POPS), 1,2‐dimyristoyl‐sn‐glycero‐3‐phosphocholine (DMPC)/POPS, and 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine (POPC)/POPS. Retention factors were calculated from the effective electrophoretic mobilities of the analytes under LEKC and CZE conditions and from the effective electrophoretic mobilities of the liposomes, determined by CZE with a polyacrylamide‐coated capillary. Determining the liposome mobilities in this way proved to be a good alternative to the conventional method employing a liposome marker compound. The log k values of the analytes for the different liposome dispersed phases were correlated with one another. In addition, correlation curves were determined between log k and calculated octanol–water partition coefficients. The results showed that the zwitterionic phospholipid in the liposome has a major impact on the interactions between the tested compounds and the lipid membranes.
Determination of rupatadine in pharmaceutical formulations by a validated stability‐indicating MEKC method
Authors: Nogueira Daniele Rubert , da Silva Sangoi Maximiliano , da Silva Lucélia Magalhães , Todeschini Vítor , Dalmora Sérgio Luiz 
Published: August 2008

AbstractA stability‐indicating MEKC was developed and validated for the analysis of rupatadine in tablet dosage forms, using nimesulide as internal standard. The MEKC method was performed on a fused‐silica capillary (50 μm id; effective length, 40 cm). The BGE consisted of 15 mM borate buffer and 25 mM anionic detergent SDS solution at pH 10. The capillary temperature was maintained at 35°C and the applied voltage was 25 kV. The injection was performed using the hydrodynamic mode at 50 mbar for 5 s, with detection by photodiode array detector set at 205 nm. The method was linear in the range of 0.5–150 μg/mL (r2= 0.9996). The specificity and stability‐indicating capability of the method were proven through degradation studies inclusive by MS, and showing also that there was no interference of the excipients and no increase of the cytotoxicity. The accuracy was 99.98% with bias lower than 1.06%. The LOD and LOQ were 0.1 and 0.5 μg/mL, respectively. The proposed method was successfully applied for the quantitative analysis of rupatadine in pharmaceutical formulations, and the results were compared to a validated RP‐LC method, showing non‐significant difference (p>0.05).
Analytical and semi‐preparative enantioseparation of organic phosphonates on a new immobilized amylose based chiral stationary phase
Authors: Zhang Yuping , Song Baoan , Bhadury Pinaki S. , Hu Deyu , Yang Song , Shi Xia , Liu Dongmei , Jin Linhong 
Published: August 2008

AbstractTwo chiral stationary phases derived from derivatized amylose (Chiralpak AD‐H and Chiralpak IA) have been used to separate the enantiomers of new diethyl benzamidoarylmethylphosphonates. The data obtained indicate that all the studied compounds could be easily baseline resolved on both columns. Owing to the different techniques involved in their preparation, the two stationary phases differ in their abilities to effect enantiomeric separation. The semi‐preparative separation of all compounds was executed successfully inn‐hexane/EtOH on the new immobilized Chiralpak IA column. The analytical assessment of the enantiomeric excess values of all collected fractions was higher than 97%. The stereochemical configuration for the F1 fraction of a diethyl benzamidoarylmethylphosphonate was determined by X‐ray diffraction structure analysis.
Recent progress of online sample preconcentration techniques in microchip electrophoresis
Authors: Sueyoshi Kenji , Kitagawa Fumihiko , Otsuka Koji 
Published: August 2008

AbstractMicrochip electrophoresis (MCE) has been advanced remarkably by the applications of several separation modes and the integration with several chemical operations on a single planer substrate. MCE shows superior analytical performance, e.g., high‐speed analysis, high resolution, low consumption of reagents, and so on, whereas low‐concentration sensitivity is still one of the major problems. To overcome this drawback, various online sample preconcentration techniques have been developed in MCE over the past 15 years, which have successfully enhanced the detection sensitivity in MCE. This review highlights recent developments in online sample preconcentration in MCE categorized on the basis of “dynamic” and “static” methods. The dynamic techniques including field amplified stacking, ITP, sweeping, and focusing have been easily applied to MCE, which provide effective enrichments of various analytes. The static techniques such as SPE and filtration have also been combined with MCE. In the static techniques, extremely high preconcentration efficiency can be obtained, compared to the dynamic methods. This review provides comprehensive tables listing the applications and sensitivity enhancement factors of these preconcentration techniques employed in MCE.
Determination of four aromatic amines in water samples using dispersive liquid–liquid microextraction combined with HPLC
Authors: Wang Xuedong , Fu Lingyan , Wei Guohui , Hu Jia , Zhao Xinna , Liu Xiujuan , Li Yanyan 
Published: August 2008

AbstractA new method for the determination of four aromatic amines in water samples was developed by using dispersive liquid–liquid microextraction (DLLME) technique combined with HPLC‐variable wavelength detection (HPLC‐VWD). In this extraction method, 0.50 mL methanol (as dispersive solvent) containing 25.0 μL tetrachloroethane (as extraction solvent) was rapidly injected by a syringe into 5.00 mL water sample. Accordingly, a cloudy solution was formed. After centrifugation for 2 min at 4000 rpm, the fine droplets of the tetrachloroethane containing the analytes were sedimented in the bottom of the conical test tube (7 ± 0.2 μL). Then, 5.0 μL of the settled phase was determined by HPLC‐VWD. Parameters such as the kind and volume of extraction solvent and dispersive solvent, extraction time, and salt concentration were optimized. Under the optimum conditions, the enrichment factors ranged from 41.3 to 94.5. Linearity was observed in the range of 5–5000 ng/mL. The LODs based on S/N of 3 ranged from 0.8 to 1.8 ng/mL. The RSDs (for 400 ng/mL of p‐toluidine and o‐chloroaniline, 100 ng/mL of p‐chloroaniline and p‐bromoaniline) varied from 4.1 to 5.3% (n = 6). The water samples collected from rivers and lakes were successfully analyzed by the proposed method and the relative recoveries were in the range of 85.4–111.7% and 90.2–101.3%, respectively.
Comparison of solid‐phase sorbents for the determination of fluoroquinolone antibiotics in wastewater
Authors: Zorita Saioa , Larsson Lennart , Mathiasson Lennart 
Published: August 2008

AbstractThree different SPE sorbents (weak cation exchange, mixed cation exchange, and hydrophobic–lipophilic balance polymers) were compared in terms of recovery, precision, and the effect of matrix components on analyte response for the determination of fluoroquinolones antibiotics. The influence of ethylenediaminetetraacetic acid disodium salt (Na2‐EDTA) was as well tested. Two of the sorbents, hydrophilic–lipophilic balance (HLB) and weak cation exchange (WCX), turned out to be suitable for ultratrace analysis. HLB sorbent showed higher capacity for analyte trapping and better precision while weak cation exchange sorbent had a superior performance in terms of selectivity. In complex samples, the higher capacity of HLB was outweighed by the higher selectivity of WCX when considering the LODs of the methods.
Neutral octadecyl monolith for reversed phase capillary electrochromatography of a wide range of solutes
Authors: Karenga Samuel , El Rassi Ziad 
Published: August 2008

AbstractA neutral octadecyl monolithic (ODM) column for RP capillary electrochromatography (RP‐CEC) has been developed. The ODM column was prepared by the in situ polymerization of octadecyl acrylate (ODA) as the monomer and trimethylolpropanetrimethacrylate (TRIM) as the crosslinker, in a ternary porogenic solvent containing cyclohexanol, ethylene glycol, and water. The ODM column exhibited cathodal EOF over a wide range of pH and ACN concentration in the mobile phase despite the fact that it was devoid of any fixed charges. It is believed that the EOF is due to the adsorption of ions from the mobile phase onto the surface of the monolith thus imparting to the neutral ODM column the zeta potential necessary to support the EOF required for mass transport across the monolithic column. Furthermore, the adsorption of mobile phase ions to the neutral monolith modulated solute retention and affected the separation selectivity. The wide applications of the neutral ODM column were demonstrated by its ability to separate a wide range of small and large solutes, both neutral and charged. While the separation of the neutral solutes was based on RP retention mechanism, the charged solutes were separated on the basis of their electrophoretic mobility and hydrophobic interaction with the C18 ligands of the stationary phase. As a typical result, the neutral monolithic column was able to separate peptides quite rapidly with a separation efficiency of nearly 200 000 plates/m, and this efficiency was exploited in tryptic peptide mapping of standard proteins, e. g., lysozyme and cytochrome C, by isocratic elution.
Determination of enrofloxacin and ciprofloxacin in milk using molecularly imprinted solid‐phase extraction
Authors: Yan Hongyuan , Tian Minglei , Row Kyung Ho 
Published: August 2008

AbstractA molecularly imprinted solid‐phase extraction procedure was developed for the simultaneous identification of enrofloxacin and its active metabolite, ciprofloxacin, in milk samples. Water‐compatible molecularly imprinted polymers synthesized in a water–methanol system show a high degree of cross‐reactivity for enrofloxacin and ciprofloxacin in aqueous environments. The imprinted particles were applied as selective sorbents in a solid‐phase extraction process focusing upon complex milk matrices, which allowed the matrix compounds present in milk samples to be removed effectively. The extracts were sufficiently clean for further chromatographic analysis, and no interference originating from the biological matrix was observed. The mean recoveries of enrofloxacin and ciprofloxacin from milk sample were 82.6–93.5% and 81.2–94.8%, respectively, with the RSD less than 7.5%. This method is simple and sensitive, and is therefore an alternative tool to the existing HPLC methods for analyzing residual enrofloxacin and ciprofloxacin in biological samples.
Development and validation of a ultra performance LC‐ESI/MS method for analysis of metabolic phenotypes of healthy men in day and night urine samples
Authors: Wang Xijun , Lv Haitao , Zhang Guangmei , Sun Wenjun , Zhou Dixin , Jiao Guozheng , Yu Yang 
Published: August 2008

AbstractUltra‐performance LC coupled to quadrupole TOF/MS (UPLC‐QTOF/MS) in positive and negative ESI was developed and validated to analyze metabolite profiles for urine from healthy men during the day and at night. Data analysis using principal components analysis (PCA) revealed differences between metabolic phenotypes of urine in healthy men during the day and at night. Positive ions with mass‐to‐charge ratio (m/z) 310.24 (5.35 min), 286.24 (4.74 min) and 310.24 (5.63 min) were elevated in the urine from healthy men at night compared to that during the day. Negative ions elevated in day urine samples of healthy men included m/z 167.02 (0.66 min), 263.12 (2.55 min) and 191.03 (0.73 min), whilst ions m/z 212.01 (4.77 min) were at a lower concentration in urine of healthy men during the day compared to that at night. The ions m/z 212.01 (4.77 min), 191.03 (0.73 min) and 310.24 (5.35 min) preliminarily correspond to indoxyl sulfate, citric acid and N‐acetylneuraminic acid, providing further support for an involvement of phenotypic difference in urine of healthy men in day and night samples, which may be associated with notably different activities of gut microbiota, velocity of tricarboxylic acid cycle and activity of sialic acid biosynthesis in healthy men as regulated by circadian rhythm of the mammalian bioclock.
Assessing and reporting the quality of commercial weather forecasts
Authors: Mailier Pascal J. , Jolliffe Ian T. , Stephenson David B. 
Published: August 2008

AbstractIn 2005 the Royal Meteorological Society commissioned a study to examine current issues regarding the quality (fitness for purpose) of commercial weather forecasts in the United Kingdom. UK commercial weather forecast providers and users were consulted by means of on‐line questionnaires, interviews, visits and an open workshop discussion. Results from this consultation uncovered significant deficiencies in the methodologies and in the communication of forecast quality assessments, a lack of open dialogue and transparency in the industry, and that some users may be indifferent to forecast quality. Descriptive or worded forecasts cannot be assessed objectively. However, suitable quality assessment methods are available for nearly all types of quantitative forecasts identified in the consultation. The crucial importance of choosing proper quality assessment metrics, the impact of their statistical properties on results and the need to estimate the statistical significance of quality assessment results were exemplified by means of four case studies, one of which is presented in this paper. The findings from this study have led to a set of practical recommendations aiming to establish the discipline and rigour that are necessary for achieving best practice in the quality assessment of weather forecasts. Specific recommendations were also made to the Royal Meteorological Society to set up a special commission that would promote a sense of community within the industry, and to run an accreditation scheme that would encourage best practice on a voluntary basis. Copyright © 2008 Royal Meteorological Society