bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring nutritional modes of cultivation for enhancing lipid accumulation in microalgae
Authors: Ratha Sachitra Kumar , Babu Santosh , Renuka Nirmal , Prasanna Radha , Prasad Rachapudi Badari Narayana , Saxena Anil Kumar
Published: June 2012

The objective of this study was to identify the most promising nutritional mode of growth for enhanced biomass and lipid productivity in a set of twenty microalgal strains, grown under photoautotrophic and mixotrophic/heterotrophic conditions using 2% glucose as carbon source. These included four cyanobacterial strains (Cyanosarcina, Phormidium, Nostoc and Anabaena) and sixteen green algae belonging to six genera (five strains each of Chlorella and Chlorococcum, two of Scenedesmus and one each of Chlamydomonas, Kirchneria, Bracteacoccus and Ulothrix). Lipid productivity ranged from 2–13% under photoautotrophic conditions, 1.7–32% under mixotrophic conditions and 0.9–20% under heterotrophic conditions. MIC‐G5 Chlorella sp. followed by MIC‐G11 Chlorella sp. exhibited the highest cellular lipid content (355 and 271 μg/ml) and lipid productivity of 32% and 28% respectively in mixotrophic condition. In the glucose supplemented conditions (heterotrophic), a significant reduction in PUFA from 25.1 to 9.4, 29.2 to 12.4 and 44.7 to 10.2 was observed in MIC‐G4, MIC‐G5 and MIC‐G11, respectively. A remarkable enhancement of 33–70% in SFA was recorded under mixotrophic conditions. As the quality of biodiesel is based on high SFA and low PUFA, our results illustrate the significance of glucose supplemented condition as a promising strategy for generating high value biodiesel from algae.
Study of the siderophore‐producing Trichoderma asperellum Q1 on cucumber growth promotion under salt stress
Authors: Qi Weizhen , Zhao Lei
Published: June 2012

Trichoderma spp. are versatile beneficial fungi which can stimulate growth and plant resistance to biotic and abiotic stresses. In this study, the potential of Trichoderma isolate in promoting the cucumber growth under salt stress and its possible mechanisms were investigated. Strain Q1 was isolated from the rhizosphere of cucumber in greenhouse in China and identified as Trichoderma asperellum based on its morphological features and the molecular phylogenetic analyses. It exhibited some plant growth‐promoting attributes of phosphate solubilization, 1‐aminocyclopropane‐1‐carboxylate (ACC) deaminase activity, auxin and siderophore production. In pot trials, applying strain Q1 to cucumber plant had significantly promoted seedlings growth and alleviated the growth suppression induced by salt stress as confirmed by the changes in growth phenotype and several biochemical and physiological parameters. In solution culture experiments, the growth of cucumber seedlings was increased and the percentage of wilted cucumber seedlings was decreased in the treatment of siderophore‐containing culture filtrate (SCF) of strain Q1 with insoluble Fe3+ under salt stress. These results indicated that T. asperellum Q1 has a real potential to enhance cucumber growth by inducing physiological protection under saline stress, and its siderophores showed sign of alleviating negative effect of salinity and available iron deficiency.
HBV regulated RhoC expression in HepG2.2.15 cells by enhancing its promoter activity
Authors: Tian Yuanyuan , Liu Yunzhi , Qu Jialin , Li Kai , Qin Dongdong , Huang Ailong , Tang Hua
Published: June 2012

Many studies showed that RhoC‐GTPases are central molecules in oncogenic transformation. The expression of RhoC is significantly increased in hepatocellular carcinoma (HCC). HBV is the major risk factor for HCC. However, it is unknown whether HBV regulating RhoC expression. In this study, we showed the RhoC expression was significantly higher in HepG2.2.15 than that in HepG2 cells. HBV could up‐regulate RhoC expression through enhancing the activity of its promoter, and HBs and HBx may involve in this process. After silencing HBs and HBx expressions by using RNA interference, the expression of RhoC in HepG2.2.15 cells could be obviously inhibited. These results would provide useful information for understanding mechanism of HCC induced by HBV infection.
The stability and activity of recombinant Helicobacter pylori HtrA under stress conditions
Authors: Hoy Benjamin , Brandstetter Hans , Wessler Silja
Published: June 2012

The bifunctional protein HtrA displays chaperone and protease activities, enabling bacteria to cope with environmental stress conditions such as heat shock or extreme pH by orchestrating protein folding or degradation. Recently, we added a novel aspect to HtrA functions by identifying HtrA of the human pathogen and class I carcinogen Helicobacter pylori (Hp) as a secreted virulence factor that cleaves the cell adhesion molecule and tumor suppressor E‐cadherin. In this study, we analyzed the structural integrity and activity of oligomeric HtrA from Hp under stress conditions. Examining different parameters, HtrA oligomers were investigated by casein zymography and HtrA activity was further analyzed in in vitro cleavage assays using E‐cadherin as a substrate. HtrA showed temperature‐dependent disintegration of oligomers. Denaturing agents targeting hydrogen bonds within HtrA destabilized HtrA oligomers while reducing agents disrupting disulfide bonds had no effect. Optimal proteolytic activity was dependent on a neutral pH; however, addition of mono‐ and divalent salts or reducing agents did not interfere with proteolytic activity. These data indicate the HtrA is active under stress conditions which might support Hp colonizing in the gastric environment.
Ag‐nanoparticle‐modified single Ag nanowire for detection of melamine by surface‐enhanced Raman spectroscopy
Authors: Chen Li‐Miao , Liu You‐Nian
Published: June 2012

Silver nanowires synthesized by a solvothermal method were used as templates for fabricating silver‐nanoparticle‐decorated silver (AgNP/Ag) nanowires. The number density and particle size of Ag nanoparticles can be controlled by varying the concentration of Ag precursor. Single AgNP/Ag nanowire exhibited strong surface‐enhanced Raman scattering effect. Detection of melamine molecules at concentrations as low as 1.0 × 10−8 M was used as an example to show the possible applications of such AgNP/Ag nanowires. Their application in rapid detection of melamine in milk solution was further demonstrated. It was shown that melamine in milk solution at a low concentration of 5.0 × 10−8 M can be easily detected with little sample pretreatment. The results demonstrate the potential of single AgNP/Ag nanowire as a surface‐enhanced Raman scattering substrate for convenient and sensitive detection of trace amounts of melamine in a complex mixture. Copyright © 2012 John Wiley & Sons, Ltd.
Detection of migration of phthalates from agglomerated cork stoppers using HPLC‐MS/MS
Authors: Sendón Raquel , Sanches‐Silva Ana , Bustos Juana , Martín Patricia , Martínez Nuria , Cirugeda Ma Eugenia
Published: June 2012

Agglomerated stoppers are manufactured from natural cork granules and adhesives. Esters, such as phthalates and adipates, are commonly used in adhesives at concentrations of typically 2–5%. Because of this, and regarding consumer safety, it is necessary to ensure that these compounds do not migrate into the beverage where the cork stopper is used. A reversed‐phase high performance liquid chromatography method with tandem mass spectrometry detection is developed for the separation of nine phthalates into 12% ethanol, used as simulant of alcoholic beverages. The chromatographic separation was carried out with a Luna C18 (2) HSTcolumn (50 × 3.0 mm, 2.5 μm) with a gradient elution of water/methanol with 0.1% acetic acid at 300 μL min−1. The method was validated for four selected phthalates: di‐butylphthalate, di‐isononylphthalate, di‐isodecylphthalate, and butyl‐benzyl phthalate, with recoveries ranging between 95% and 112% and intralaboratory precision (RSD) between 5 and 14%, depending on the phthalate. The lowest quantification limit, 0.15 mg kg−1, was achieved for di‐butylphthalate. Nevertheless, in all cases, the limits obtained guarantee the method utility if restriction limits set in Commission Regulation No 10/2011 for plastic materials are taken into account.
Solid‐phase extraction in the determination of gold, palladium, and platinum
Authors: Mladenova Elisaveta , Karadjova Irina , Tsalev Dimiter L.
Published: June 2012

A simple classification of various sorbents and solid‐phase extraction procedures used for preconcentration of trace levels of Au, Pd, and Pt from different sample types is proposed in this review article. The large variety of available sorbents/procedures has been organized according to expected mechanisms of sorption process (complex formation; ion exchange; adsorption; ion‐imprinted or molecularly imprinted polymers); according to the kind of monomeric units of the polymer matrix as well as on the basis of the kind of functional group responsible for main performance characteristics (selectivity, capacity) of the sorbent. Advantages of chemically modified sorbents, sulfur‐containing sorbent extractants, and ion‐imprinted polymers, together with rational pretreatment by means of microwave treatments, scaling down of enrichment, and quantification by means of flow and flow injection approaches are given. Preferred instrumental techniques for quantification of ppb levels of Au, Pd, and Pt in prepared concentrates/column eluates are multielement instrumental techniques: inductively coupled plasma optical emission spectrometry (ICP‐OES), and inductively coupled plasma mass spectrometry (ICPMS). Excellent limits of detection at picogram levels of these analytes are provided by electrothermal atomic absorption spectrometry (ETAAS), generally in single‐element mode and the neutron activation analysis (NAA), while X‐ray fluorescence spectrometry and flame AAS are rarely applied because of lack of sensitivity at sub‐ppm levels of Au, Pd, and Pt. Some problems of atomic spectrometric quantification techniques and their representative limits of detection are given. Recent applications to geological, industrial, pharmaceutical, biological, and other materials are tabulated. References have been selected mostly from the period 1995 to 2010.
Liquid chromatography tandem mass spectrometry for the simultaneous determination of mequindox and its metabolites in porcine tissues
Authors: Zeng Dongping , Shen Xiangguang , He Limin , Ding Huanzhong , Tang Youzhi , Sun Yongxue , Fang Binghu , Zeng Zhenling
Published: June 2012

A rapid liquid chromatography tandem mass spectrometric method was developed for the simultaneous determination of mequindox and its five metabolites (2‐isoethanol mequindox, 2‐isoethanol 1‐desoxymequindox, 1‐desoxymequindox, 1,4‐bisdesoxymequindox, and 2‐isoethanol bisdesoxymequindox) in porcine muscle, liver, and kidney, fulfilling confirmation criteria with two transitions for each compound with acceptable relative ion intensities. The method involved acid hydrolysis, purification by solid‐phase extraction, and subsequent analysis with liquid chromatography tandem mass spectrometry using electrospray ionization operated in positive polarity with a total run time of 15 min. The decision limit values of five analytes in porcine tissues ranged from 0.6 to 2.9 μg/kg, and the detection capability values ranged from 1.2 to 5.7 μg/kg. The results of the inter‐day study, which was performed by fortifying porcine muscle (2, 4, and 8 μg/kg), liver, and kidney (10, 20, and 40 μg/kg) samples on three separate days, showed that the accuracy of the method for the various analytes ranged between 75.3 and 107.2% with relative standard deviation less than 12% for each analyte.
Less common applications of monoliths: V. Monolithic scaffolds modified with nanostructures for chromatographic separations and tissue engineering
Authors: Krenkova Jana , Foret Frantisek , Svec Frantisek
Published: June 2012

Scaffolds modified with nanostructures are recently finding use in a broad range of applications spanning from chromatographic separations to tissue engineering. This continuation of the review series on design and applications of monolithic materials covers some of the less common monoliths including use of nanostructures in preparation, modifications, and applications.
Confirmatory development and validation of HPLC‐DADmethod for the determination of tetracyclines in gilthead seabream (Sparus aurata) muscle tissue
Authors: Evaggelopoulou Evaggelia N. , Samanidou Victoria F.
Published: June 2012

A confirmatory high‐pressure liquid chromatographic method for the determination of nine tetracyclines in Sparus aurata (gilthead seabream) muscle tissue is developed and presented herein. Tetracycline, 4‐epi‐tetracycline, oxytetracycline, 4‐epi‐oxytetracycline, chlortetracycline, 4‐epi‐chlortetracycline, doxycycline, methacycline and demeclocycline were separated on a Kromasil, C18 (250 mm × 4 mm, 5 μm) analytical column by gradient elution with a mobile phase consisting of 0.001 M ethylenediaminetetraacetic acid/sodium salt and acetonitrile at 25°C. Diode array detection with monitoring at 280 nm (for the determination of chlortetracycline, 4‐epi‐chlortetracycline, methacycline and demeclocycline) and 355 nm (for tetracycline, 4‐epi‐tetracycline, oxytetracycline, 4‐epi‐oxytetracycline and demeclocycline) was applied for peak identification and quantification of analytes. Examined antibiotics were isolated from gilthead seabream tissue by leaching using a citrate buffer (pH 4.0) and purified by solid phase extraction using Oasis HLB(200 mg/6 mL) cartridges. The developed method was fully validated in terms of selectivity, linearity, accuracy, precision, stability and sensitivity according to the European Union Decision 2002/657/EC.
Novel molecularly imprinted polymers based on multiwalled carbon nanotubes with bifunctional monomers for solid‐phase extraction of rhein from the root of kiwi fruit
Authors: Chen Xing , Zhang Zhaohui , Yang Xiao , Liu Yunan , Li Jiaxing , Peng Mijun , Yao Shouzhuo
Published: July 2012

A novel molecularly imprinted polymers based on multiwalled carbon nanotubes synthesized by precipitate polymerization was applied as a selective sorbent for separation and determination of rhein (4,5‐dihydroxyanthraquinone‐2‐carboxylic acid) from the root of kiwi fruit samples coupled with high performance liquid chromatography (HPLC). The molecularly imprinted polymers were prepared with methacrylic acid and 4‐vinylpyridine as bifunctional monomers. The chemical structure of the molecularly imprinted polymers was characterized by Fourier transform infrared spectrometer. The equilibrium rebinding experiment and competitive adsorption experiment showed that these imprinted polymers exhibited good adsorption ability toward rhein. The Langmuir adsorption equilibrium constant, Km, and theoretical maximum adsorption capacity, Qm, were estimated to be 0.43 and 6.77 mg g−1, respectively. Compared with molecularly imprinted polymers prepared with methacrylic acid or 4‐vinylpyridine solely, the molecularly imprinted polymers synthesized with bifunctional monomers showed enhanced molecular imprinting effect and higher adsorption capacity for the template rhein. The performances of the molecularly imprinted polymers utilized as solid phase extraction sorbent were investigated in detail. The molecularly imprinted polymers prepared by the method proposed in this work could successfully apply to extraction and determination of rhein from the root of kiwi fruit samples coupled with HPLC.
Determination of trace anions in liquefied petroleum gas using liquid absorption and electrokinetic migration for enrichment followed by ion chromatography
Authors: Li Meilan , Yang Jianmin , Li Hai‐Fang , Lin Jin‐Ming
Published: June 2012

A simple sample enrichment technique, electrokinetic migration enrichment in single phase using a designed device, coupled with ion chromatography is presented for the determination of four anions (H2PO4−, Cl−, NO3−, and SO42−) in liquefied petroleum gas by liquid adsorption. The electrokinetic migration enrichment is based on the phenomenon of ion electrokinetic migration to the opposite electrode. When the anions migrated to the anode in a smaller volume chamber under the electric field, the concentration was realized. The main parameters affecting enrichment efficiency of applied voltage and enrichment time were investigated. The ion chromatography condition for anions separation was also studied. Under the optimal electrokinetic migration enrichment and ion chromatography conditions, the four anions were detected simultaneously with good linear relationship (r2 = 0.9908–0.9968) and high precisions (less than 5% of the relative standard deviations of peak areas). The limits of detection of anions (S/N of 3) were in the range of 8–600 μg L−1. The enrichment factors of the four anions ranged from 3.1 to 5.8. The established method was successfully applied to the analysis of the trace anions in liquefied petroleum gas by liquid adsorption with satisfactory results. The advantages of this method are simple operation and low cost.
Centrifugal countercurrent chromatography to elucidate surface differences of adipose tissue‐derived stem cells
Authors: Sebastián Ramiro , Calvin Víctor , Mendoza Noelia , Pérez‐Pé Rosaura , García David , Carreras Carmen , Cebrián‐Pérez José A. , Muiño‐Blanco Teresa
Published: June 2012

The current methods of isolation of adipose tissue‐derived stem cells result in a heterogeneous population that might interfere with their differentiation potential and makes it difficult to compare the results between different groups. Partition in aqueous two‐phase systems is one of the few techniques that separate cells on the basis of surface properties, gentle enough to isolate fragile cell types in isotonic conditions without altering their structure, and can be easily scaled. In this study, stem cells isolated from human adipose tissue seeded and expanded in vitro were fractionated by using centrifugal countercurrent distribution in an aqueous two‐phase system. The separated subpopulations revealed the high heterogeneity of adipose tissue‐derived stem cell samples. Comparative partition analyses showed that aging induces a loss of heterogeneity, which is not due to a loss of cell viability associated to age. The phosphatidylserine externalization, an apoptotic feature, is the main factor in cell partition that results in a decreased hydrophobicity of the cell surface. This procedure may be suitable for separating adipose tissue‐derived stem cell populations enriched in some functional and/or structural surface characteristics. The possibility of a very effective separation of different subpopulations in opposite phases would be an interesting development of the method.
On the use of response surface strategy to elucidate the electrophoretic migration of carbohydrates and optimize their separation
Authors: Sarazin Cédric , Delaunay Nathalie , Costanza Christine , Eudes Véronique , Gareil Pierre , Vial Jérôme
Published: June 2012

This paper focuses on the optimization with a design of experiments of a new CE method for the simultaneous separation of four carbohydrates of interest (fructose, glucose, lactose, and sucrose) and five potentially interfering carbohydrates (ribose, xylose, maltose, mannose, and galactose) with a highly alkaline separation electrolyte for subsequent applications to food, beverage, forensic, or pharmaceutical samples. First, the factors that potentially affect the carbohydrate migration were identified: NaOH concentration in the separation electrolyte, separation temperature, and separation electrolyte conductivity. A central composite design was then carried out to determine and model the effects of these three factors on normalized migration times and separation efficiency. From the model, an optimization of the separation was carried out using a desirability analysis based on resolutions between adjacent peaks and analysis time. The optimum conditions obtained were a separation electrolyte composed of 98 mM NaOH and 120 mM NaCl to adjust the conductivity at 4.29 S/m and a separation temperature fixed at 26.5°C. Finally, these conditions were experimentally confirmed and the robustness of the obtained separation was checked.
Isolation of mono‐caffeoylquinic acids from tobacco waste using continuous resin‐based pre‐separation and preparative HPLC
Authors: Wang Jun , Lu Dingqiang , Liang Yao , Zhao Hui , Luo Min , Ling Xiuquan , Ouyang Pingkai
Published: June 2012

Three isomers of mono‐caffeoylquinic acid, specifically, 3‐O‐caffeoylquinic acid, 4‐O‐caffeoylquinic acid and 5‐O‐caffeoylquinic acid, were successfully isolated from a crude extract of tobacco (Nicotiana tobaccum L.) wastes using continuous resin‐based pre‐separation and preparative high‐performance liquid chromatography (HPLC). The extract of tobacco wastes was continuously pre‐separated by resin‐based columns packed with D101 and XAD‐4, yielding total mono‐caffeoylquinic acids with a purity of 67.71% and a recovery rate of 90.06%. Variables affecting resolution and productivity of three mono‐caffeoylquinic acid isomers in preparative HPLC (i.e. mobile‐phase composition, pH, flow rate and loading amount) were studied. The optimum chromatographic conditions were determined to be a mobile phase consisting of 15% (v/v) methanol and aqueous acetic acid with a pH of 4.5, a flow rate of 4.0 mL/min, a loading amount of 4 mL and a detection wavelength of 360 nm. From 300 mg of loading sample, 56.3 mg of 3‐O‐caffeoylquinic acid, 92.8 mg of 5‐O‐caffeoylquinic acid and 73.1 mg of 4‐O‐caffeoylquinic acid were obtained in a single run, each with a purity of over 98% by HPLC. The structures of the isolated compounds were elucidated by ESI‐MS, 1H-NMR and 13C-NMR spectral data.
Development and validation of a reversed‐phase liquid chromatographic method for analysis of demeclocycline and related impurities
Authors: Kahsay Getu , Maxa Jaroslav , Van Schepdael Ann , Hoogmartens Jos , Adams Erwin
Published: June 2012

A simple, robust, and rapid reversedphase high‐performance liquid chromatographic method for the analysis of demeclocycline and its impurities is described. Chromatographic separations were achieved on a Symmetry Shield RP8 (75 mm × 4.6 mm, 3.5 μm) column kept at 40°C. The mobile phase was a gradient mixture of acetonitrile, 0.06 M sodium edetate (pH 7.5), 0.06 M tetrapropylammonium hydrogen sulphate (pH 7.5) and water, A (2:35:35:28 v/v/v/v) and B (30:35:35:0 v/v/v/v) pumped at a flow rate of 1 mL/min. UV detection was performed at 280 nm. The developed method was validated according to the ICH guidelines for specificity, limit of detection, limit of quantification, linearity, precision, and robustness. An experimental design was applied for robustness study. Results show that the peak shape, chromatographic resolution between the impurities, and the total analysis time are satisfactory and better than previous methods. The method has been applied for the analysis of commercial demeclocycline bulk samples available on the market.
Identification of the oxidation products of cysteamine and cystamine byCE‐MSinterfaced by a noncommercial electrospray ionization source
Authors: Carvalho Alexandre Zatkovskis , El‐Attug Mohamed Nouri , da Silva José Alberto Fracassi , Wolfs Kris , D'Autry Ward , Hoogmartens Jos , Adams Erwin , Van Schepdael Ann
Published: June 2012

Sodium cysteamine phosphate is a prodrug derivative of cysteamine that can be used in cystinosis treatment. Although titrimetric assays are very well established and precise, iodimetric determination of sodium cysteamine phosphate requires considerably more carefulness and time from the analyst than usual. The possibility to assess sodium cysteamine phosphate by CE was evaluated by means of the quantification of its oxidation product, cystamine, which is a more suitable substance to be used as primary standard than sodium cysteamine phosphate. Apparently, this approach should be straightforward, but systematic differences between the results obtained withCEand titrimetric assays were noticed.MSandCE‐MSwere employed to aid in the investigation of the possible causes of imprecision of the sodium cysteamine phosphate titration andCEdetermination. For this purpose, a simple and inexpensiveESIsource was constructed. It was observed that cystamine is not the final product of the cysteamine and/or sodium cysteamine phosphate iodine‐oxidation and other species besides cystamine may be formed depending on the reaction conditions, which explains the difficulties observed in the sodium cysteamine phosphate quantification.
Reversed‐phase liquid chromatography without organic solvent for determination of tricyclic antidepressants
Authors: Fernández‐Navarro Juan José , Ruiz‐Ángel María José , García‐Álvarez‐Coque María Celia
Published: June 2012

The chromatographic behavior of seven tricyclic antidepressants (amitryptiline, clomipramine, doxepin, imipramine, maprotiline, nortryptiline, and trimipramine) was examined with micellar mobile phases containing the nonionic surfactant Brij‐35. Acetonitrile–water mixtures were also used for comparison purposes. Tricyclic antidepressants are moderately polar basic drugs, which are positively charged in the usual working pH. This gives rise to a strong association with the alkyl chains and residual ionized silanols in silica‐based stationary phases, which is translated in a high consumption of organic solvent to get appropriate retention times. Brij‐35 modifies the surface of the stationary phases creating a neutral bilayer that masks silanols and reduces the polarity. Consequently, the retention times are decreased. A simple chromatographic procedure for the control of tricyclic antidepressants in pharmaceutical formulations was developed, using 0.02 M Brij‐35 at pH 3 and UV detection. Satisfactory recoveries were achieved, with intra‐ and inter‐day relative standard deviations usually below 1 and 2%, respectively. The preparation of the samples was simple and only required solubilization and filtration steps previous to injection. The proposed procedure has the advantage of not using an organic solvent in the mobile phase, and the biodegradable character of Brij‐35. This makes an example of “green” liquid chromatographic analysis.
Analysis of carbofuran, carbosulfan, isoprocarb, 3‐hydroxycarbofuran, and 3‐ketocarbofuran by micellar electrokinetic chromatography
Authors: Hsu Chien‐Hua , Hu Cho‐Chun , Chiu Tai‐Chia
Published: June 2012

We developed an analytical method for the detection and quantitation of five pesticides and some of their metabolites – 3‐hydroxycarbofuran, 3‐ketocarbofuran, carbofuran, carbosulfan, and isoprocarb – using micellar electrokinetic chromatography coupled with a UV–Vis detector. The optimum separation conditions were 20 mM phosphate buffer (pH 8.0) containing 15 mM sodium dodecyl sulfate. The detection wavelength was set at 200 nm and the applied voltage was 12.5 kV. Under these conditions, baseline separation of five pesticides was achieved in 15 min, and the detection limits (S/N = 3) of 3‐hydroxycarbofuran, 3‐ketocarbofuran, carbofuran, carbosulfan, and isoprocarb were 0.3, 0.3, 0.3, 4.0, and 0.3 μM, respectively. The linear ranges for 3‐hydroxycarbofuran, 3‐ketocarbofuran, carbofuran, and isoprocarb were between 1.0 and 50.0 μM and that for carbosulfan was between 10.0 and 100.0 μM, with R2 larger than 0.995. When applied to the analysis of a carbofuran‐spiked rice sample, this approach yielded results with excellent repeatability (3.3%, n = 5), reproducibility (4.5%, n = 5), separation efficiency (>2.1 × 104 theoretical plates), and recovery (95.5 ± 1.4%, n = 5).
Optimization and validation of a nonaqueous micellar electrokinetic chromatography method for determination of polycyclic musks in perfumes
Authors: Lopez‐Gazpio Josu , Garcia‐Arrona Rosa , Ostra Miren , Millán Esmeralda
Published: June 2012

A nonaqueous micellar electrokinetic chromatography method was developed for determination of Tonalide®, Galaxolide®, and Traseolide® polycyclic musks (PCMs). These compounds are widely used as fragrance ingredients in cosmetics. The method was optimized by using a three variable Box‐Behnken experimental design and response surface methodology. A modified chromatographic response function was defined in order to adequately weigh the terms in the response function. After optimization of experimental conditions, an electrolyte solution of 195 mM SDS and 40 mM NaH2PO4 in formamide was selected for the separation of the three PCMs, and the applied voltage was fixed at 30 kV. The nonaqueous MEKC method was then checked in terms of linearity, limits of detection and quantification, repeatability, intermediate precision and accuracy, providing appropriate values (i.e. RSD values for precision never exceeding 7%, and accuracy 96–107%). Nonaqueous MEKC for determination of the selected compounds was successfully applied to the analysis of commercial perfume samples.
Residual silanols at reversed‐phase silica in HPLC – a contribution for a better understanding
Authors: Bocian Szymon , Buszewski Boguslaw
Published: June 2012

As porous silica gel is the most common adsorbent and support for bonded stationary phase synthesis, residual silanol groups are a recurring problem in the field of liquid chromatography and other separation techniques. Residual silanols most often have a negative effect on the separation process by causing peak tailing. Therefore, there was an attempt to remove residual silanols during stationary‐bonded phase synthesis. The type and surface concentration of residual silanols were measured using different instrumental techniques such as NMR and infrared spectroscopy, calorimetry, and various chromatographic methods. Residual silanols exhibit acidic characteristic and they can ionize depending on the environment. Thus, they posses cation‐exchange properties and cause the zeta potential of silica particle in liquid environment. Presented review discusses the influence of the residual silanol groups on the solvation process and retention of polar compounds. The novel methodology of residual silanols determination is presented as well as the influence of the silanols on the zeta potential of the stationary‐bonded phases in chromatographic conditions.
Profiling eicosanoids and phospholipids using LC‐MS/MS: Principles and recent applications
Authors: Ecker Josef
Published: June 2012

Eicosanoids are potent lipid mediators involved in numerous physiological and pathophysiological processes. Precursors are polyunsaturated fatty acids liberated from membrane phospholipids. Thus, profiling and quantification of these molecules has gained a lot of attention during last years. Eicosanoids and phospholipids are commonly profiled by LC‐MS/MSbecause this technique allows accurate quantification within acceptable run‐times. This article therefore focuses on liquid chromatography and the ESI‐MS/MS analysis of proinflammatory lipid mediators, particularly arachidonic acid (C20:4) derived eicosanoids and their precursors phospholipids. Recent analytical developments for quantification of these compounds are highlighted and analytical challenges are discussed. Furthermore, applications such as the use of these molecules as biomarkers are presented.
Separation methods for captopril in pharmaceuticals and biological fluids
Authors: Mansour Fotouh R. , Danielson Neil D.
Published: June 2012

Captopril (CAP) is an orally active angiotensin‐converting enzyme (ACE) inhibitor and has been widely used for management of hypertension and congestive heart failure. CAP lacks an aromatic chromophore required for facile direct UV detection and also has two chiral centers. These factors can render the determination of CAP in complex matrices challenging. This review covers more than 20 years of analytical research on this drug, focusing mainly on pharmaceutical and biological applications. The primary separation techniques discussed are gas chromatography, liquid chromatography, and capillary electrophoresis. The structures of the CAP derivatizing agents as well as a table summarizing various HPLC methods are provided. A discussion of key recent chromatographic and electrophoretic methods for other ACE inhibitors is also present.
Chiral separation using capillary electromigration techniques based on ligand exchange principle
Authors: Zhang Haizhi , Qi Li , Mao Lanqun , Chen Yi
Published: June 2012

Over the last couple of decades, researchers have developed diverse chiral separation methods emerged from a few chiral separation principles. This review article is primarily focused on the application of chiral ligand‐exchange (CLE) principle in capillary electromigration techniques, such as capillary electrophoresis (CE) and capillary electrochromatography (CEC). First, the most commonly used CLE‐CZE separation mode by using different kinds of central ions, such as Cu(II), Zn(II), borate ion, and other metal ions, has been introduced. Meanwhile, several kinds of surfactants have been applied as the micelle‐forming agents in the CLE micellar electrokinetic chromatography mode. The highlight of recent research of CLE‐CEC is the exploitation of novel columns for chiral separation. Then, two kinds of capillary columns, packed capillary and monolithic capillary column, have been briefly described. Finally, the effective application of these chiral separation methods has been presented, including the application in life science and food analysis area.
Preparation and applications of hybrid organic–inorganic monoliths: A review
Authors: Zhu Tao , Row Kyung Ho
Published: June 2012

This review presents an overview of the properties of hybrid organic–inorganic monolithic materials and summarizes the recent developments in the preparation and applications of these hybrid monolithic materials. Hybrid monolithic materials with porosities, surface functionalities, and fast dynamic transport have developed rapidly, and have been used in a wide range of applications owing to the low cost, good stability, and excellent performance. Basically, these materials can be divided into two major types according to the chemical composition: hybrid silica‐based monolith (HSM) and hybrid polymer‐based monolith (HPM). Compared to the HPM, HSM monolith has been attracting most wide attentions, and it is commonly synthesized by the sol–gel process. The conventional preparation procedures of two type's hybrid organic–inorganic monoliths are addressed. Applications of hybrid organic–inorganic monoliths in optical devices, capillary microextraction (CME), capillary electrochromatography (CEC), high performance liquid chromatography (HPLC), and chiral separation are also reviewed.
Droplet microfluidics based microseparation systems
Authors: Xiao Zhiliang , Niu Menglei , Zhang Bo
Published: June 2012

Lab on a chip (LOC) technology is a promising miniaturization approach. The feature that it significantly reduced sample consumption makes great sense in analytical and bioanalytical chemistry. Since the start of LOC technology, much attention has been focused on continuous flow microfluidic systems. At the turn of the century, droplet microfluidics, which was also termed segmented flow microfluidics, was introduced. Droplet microfluidics employs two immiscible phases to form discrete droplets, which are ideal vessels with confined volume, restricted dispersion, limited cross‐contamination, and high surface area. Due to these unique features, droplet microfluidics proves to be a versatile tool in microscale sample handling. This article reviews the utility of droplet microfluidics in microanalytical systems with an emphasize on separation science, including sample encapsulation at ultra‐small volume, compartmentalization of separation bands, isolation of droplet contents, and related detection techniques.
Rapid determination of pesticide residues in herbs using selective pressurized liquid extraction and fast gas chromatography coupled with mass spectrometry
Authors: Du Gang , Xiao Yao , Yang Hua‐Rong , Wang Li , Song Yue‐lin , Wang Yi‐Tao
Published: July 2012

A selective pressurized liquid extraction and gas chromatography coupled with triple quadrupole mass spectrometer method was developed for simultaneous determination of 52 pesticide residues in medicine and food dual‐purpose herbs. The developed extraction method integrated extraction and cleanup processes for sample preparation. The sorbents, 5 g Florisil and 100 mg graphitized carbon black, were placed inside the extraction cell to remove matrix interferences. Optimized conditions of selective pressurized liquid extraction were ethyl acetate as extraction solvent, 120°C of extraction temperature, 6 min of static extraction time, 50% of flush volume extracted for two cycles. An ultra inert capillary GC‐MS HP‐5 UI column (20 m × 0.18 mm id, 0.18 μm) and column backflush system were used for the analysis. Multiple‐reaction monitoring was employed for the quantitative analysis with electron ionization mode. All calibration curves showed good linearity (r2 > 0.995) within the test ranges. The average recoveries of most pesticides were from 81 to 118%. The validated method was successfully applied for the determination of pesticide residues in four herbs. The results indicate that selective pressurized liquid extraction and GC‐MS/MS is a sensitive and reliable analytical method for the simultaneous determination of multiple pesticide residues in herbs.
Two‐step liquid phase microextraction combined with capillary electrophoresis: A new approach to simultaneous determination of basic and zwitterionic compounds
Authors: Nojavan Saeed , Moharami Arezoo , Reza Fakhari Ali
Published: July 2012

In this work, two‐step hollow fiber‐based liquid‐phase microextraction procedure was evaluated for extraction of the zwitterionic cetirizine (CTZ) and basic hydroxyzine (HZ) in human plasma. In the first step of extraction, the pH of sample was adjusted at 5.0 in order to promote liquid‐phase microextraction of the zwitterionic CTZ. In the second step, the pH of sample was increased up to 11.0 for extraction of basic HZ. In this procedure, the extraction times for the first and the second steps were 30 and 20 min, respectively. Owing to the high ratio between the volumes of donor phase and acceptor phase, CTZ and HZ were enriched by factors of 280 and 355, respectively. The linearity of the analytical method was investigated for both compounds in the range of 10–500 ng mL−1 (R2 > 0.999). Limit of quantification (S/N = 10) for CTZ and HZ was 10 ng mL−1, while the limit of detection was 3 ng mL−1 for both compounds at a signal to noise ratio of 3:1. Intraday and interday relative standard deviations (RSDs, n = 6) were in the range of 6.5–16.2%. This procedure enabled CTZ and HZ to be analyzed simultaneously by capillary electrophoresis.
Comparison of two extraction methods for the determination of selective serotonin reuptake inhibitors in sewage sludge by hollow fiber liquid‐phase microextraction
Authors: Sagristà Ester , Cortés José Manuel , Larsson Estelle , Salvadó Victòria , Hidalgo Manuela , Jönsson Jan Åke
Published: July 2012

This paper presents two procedures for the determination of four selective serotonin reuptake inhibitors (citalopram, paroxetine, fluoxetine, and sertraline) and one metabolite (norfluoxetine) in sewage sludge utilizing three‐phase hollow fiber liquid‐phase microextraction (HF‐LPME). First, direct HF‐LPME was used for extraction, clean‐up, and preconcentration. The pharmaceuticals were extracted from slurry samples into an organic phase and then back‐extracted into an aqueous phase in the lumen of the hollow fiber. Second, a procedure combining pressurized hot water extraction and HF‐LPME for clean‐up and preconcentration was developed for the same analytes and matrix. The extracts were subsequently analyzed by liquid chromatography–mass spectrometry. For direct HF‐LPME, limits of detection were between 1 and 12 ng g−1 (dry weight) and the relative standard deviation (RSD) values were 3–12%. For the second method, limits of detection were approximately 6 ng g−1 for all the compounds and RSD values were 8–12%. The methods were validated by comparison of results for the same samples. Sewage sludge from a Swedish wastewater treatment plant was analyzed by both methods; average concentrations were similar for citalopram, paroxetine, and fluoxetine with values of approximately 530, 40, and 200 ng g−1, respectively.
Learning to live with black bears: A psychological model of acceptance
Authors: Zajac Ryan M. , Bruskotter Jeremy T. , Wilson Robyn S. , Prange Suzanne
Published: July 2012

The reappearance and recovery of large carnivores in human‐dominated landscapes creates a need to understand how people will respond to the presence of these animals. We tested a psychological model of acceptance to determine what variables most influence people's acceptance for black bears (Ursus americanus) in an area with an emerging black bear population (Ohio, USA). We hypothesized that people's perceptions of risk and benefit related to bears would mediate the effect of trust (in wildlife management agencies) and personal control (over interactions with and management of wildlife) on acceptance for black bears. We used a mail‐back survey of Ohio residents (n = 9,400; adjusted response rate = 35%) to assess the variables of interest and test the hypothesized model. Based on multiple criteria of model fit, the hypothesized model fit the data acceptably well. The model explained approximately 62% of the variance in acceptance, and perception of risk associated with black bears had the largest impact on the level of acceptance. As large carnivore populations expand and interactions with humans increase, our results will aid managers in designing outreach materials and communications aimed at promoting acceptance for large carnivores. Our model suggests that interventions raising an individual's social trust in the managing agency, or personal control can indirectly raise stakeholders' acceptance by reducing risk perception and increasing perception of benefit from carnivores. © 2012 The Wildlife Society.
Comparison of whole body positron emission tomography (PET)/PET‐computed tomography and conventional anatomic imaging for detecting distant malignancies in patients with head and neck cancer: A meta‐analysis
Authors: Xu Guozeng , Li Junkai , Zuo Xiaoyan , Li Chunyan
Published: July 2012

Objectives/Hypothesis:

We aimed to compare the accuracy of whole body positron emission tomography (PET)/PET‐computed tomography (CT) and conventional anatomic imaging for detecting distant malignancies in patients with head and neck cancer.

Study Design:

Meta‐Analysis.

Methods:

We performed a meta‐analysis of all available studies. We compared the performance of whole body PET/PET‐CT with that of conventional anatomic imaging by analyzing studies that had also used conventional anatomic imaging on the same patients.

Results:

Across eight studies (1,147 patients), sensitivity and specificity of PET/PET‐CT were 0.83 (95% confidence interval [CI], 0.76–0.88) and 0.96 (95% CI, 0.94–0.97), respectively, and for conventional anatomic imaging were 0.44 (95% CI, 0.29–0.61) and 0.96 (95% CI, 0.88–0.98), respectively. Subgroup analysis showed that PET/PET‐CT had higher sensitivity than conventional anatomic imaging for nasopharyngeal cancer (0.82 vs. 0.30) and non‐nasopharyngeal head and neck cancer (0.85 vs. 0.62).

Conclusions:

Compared with conventional anatomic imaging, whole body PET/PET‐CT has excellent diagnostic performance for detecting distant malignancies in patients with head and neck cancer.
The phenotypic spectrum of dystonia in Mohr–Tranebjaerg syndrome
Authors: Ha Ainhi D. , Parratt Kaitlyn L. , Rendtorff Nanna D. , Lodahl Marianne , Ng Karl , Rowe Dominic B. , Sue Carolyn M. , Hayes Michael W. , Tranebjærg Lisbeth , Fung Victor S.C.
Published: June 2012

Mohr–Tranebjaerg syndrome (MTS) is an X‐linked recessive disorder characterized by deafness and dystonia. However the phenotypic expression of dystonia has not been systematically defined. We report clinical, neurophysiological, and ophthalmological data on 6 subjects from 3 Australian kindreds, including 2 with novel mutations, together with a systematic review of the literature, in order to define the phenotypic expression of dystonia. Profound hearing impairment in affected males develops by infancy and precedes the development of dystonia, which varies in time of onset from the first to the sixth decades, with a peak in the second and third decades. Dystonia in MTS tends to be focal, segmental, or multifocal in distribution at onset, with a predilection for the upper body, variably involving the head, neck, and upper limbs. The majority of patients have progression or generalization of their dystonia regardless of age of onset. Within our 3 kindreds, we observed relative intrafamilial homogeneity but interfamilial variation. The median time to the development of moderate‐severely disabling dystonia in these subjects was 11 years. Associated features included progressive cognitive decline, pyramidal signs, and in 1 patient, gait freezing and postural instability. Optic atrophy and cortical visual impairment were both observed. We report for the first time a female patient who developed multiple disabling neurological complications of MTS. Our findings more clearly define and expand the phenotype of both the dystonia and other neurological features of MTS and have implications for the diagnosis and management of this condition. © 2012 Movement Disorder Society
Comparative Occupancy Analysis (CoOAn) – A Straightforward and Directly Applicable 3D‐QSAR Formalism to Extract Molecular Features Obligatory for Designing Potent Leads
Authors: Verma Jitender , Malde Alpeshkumar , Khedkar Santosh , Coutinho Evans
Published: June 2012

A simple and directly applicable 3D‐QSAR method, termed Comparative Occupancy Analysis (CoOAn), has been developed. The method is based on the comparison of local occupancies of fragments of an aligned set of molecules in a 3D‐grid space. The formalism commendably extracts the crucial position‐specific molecular features and correlates them quantitatively to their biological endpoints. The method has been effectively applied and efficaciously validated on three large and diverse datasetsthrombin, glycogen phosphorylase b (GPB), and thermolysin inhibitors. Several robust and statistically significant predictive 3D‐QSAR models were developed while simultaneously considering the influence of grid spacing on the accuracy of the results. The models, generated by the G/PLS chemometric method, not only unswervingly identified the obligatory chemical features but advantageously detected those that are unfavourable or detrimental for the molecular activity. The CoOAn models can profitably be used to optimize existing molecules as well as to design new leads with more desirable (and/or less detrimental) features. The activity‐modulating features (together with their distance‐constraints) extracted by the methodology can also be incorporated into a pharmacophore‐type query to search a chemical database for novel leads.
Voluntary contributions and wages in nonprofit organizations
Authors: Pennerstorfer Astrid , Trukeschitz Birgit
Published: June 2012

Voluntary work provides a major source of labor for many nonprofit organizations. Consequences of volunteers and paid staff working alongside each other in nonprofits are well documented. This article contributes to this strand of literature and investigates whether the presence of volunteer work influences paid employees' wages in nonprofit organizations. We estimated a multilevel wage equation accounting for personal characteristics of workers and characteristics of nonprofits. The analysis revealed that nonprofit organizations engaging volunteers pay lower wages to their employees. Our findings contribute to the understanding of wage‐setting behavior of nonprofits and improve the methodological approach of empirical research in this field.