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Formic Acid (formic + acid)
Kinds of Formic Acid Selected AbstractsContinuous Hydrogen Generation from Formic Acid: Highly Active and Stable Ruthenium CatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009Albert Boddien Abstract The ruthenium-catalyzed decomposition of formic acid was investigated with respect to continuous hydrogen generation and long-term stability of the catalytic systems. A highly active and stable system is presented, which was studied in batch and continuous modes for up to two months. The optimized catalyst system containing N,N -dimethyl- n -hexylamine with an in situ generated catalyst from (benzene)ruthenium dichloride dimer [RuCl2(benzene)]2 and 6 equivalents of 1,2-bis(diphenylphosphino)ethane (dppe) reached at room temperature a total turnover number (TON) of approximatly 260,000 with average turnover frequency (TOF) of about 900,h,1. Only hydrogen and carbon dioxide were detected in the produced gas mixture which makes this system applicable for direct use in fuel cells. [source] Efficient Production of the Liquid Fuel 2,5-Dimethylfuran from Fructose Using Formic Acid as a Reagent,ANGEWANDTE CHEMIE, Issue 37 2010Todsapon Thananatthanachon Dr. Drei in einem: Für die Erzeugung flüssiger Kraftstoffe aus Biomasse werden neue, vielseitige Reagentien benötigt. Ein Beispiel hierfür ist Ameisensäure, die bei der Umsetzung von Fructose in die Titelverbindung 1 drei Funktionen erfüllt: Sie vermittelt die Isomerisierung-Dehydratisierung, dient als H2 -Quelle für die Hydrierung und unterstützt die Desoxygenierung von Alkoholfunktionalitäten. [source] ChemInform Abstract: A Practical and Convenient Procedure for the N-Formylation of Amines Using Formic Acid.CHEMINFORM, Issue 27 2002Sun Ho Jung Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Synthesis of 4-Arylaminoquinazolines and 2-Aryl-4-arylaminoquinazolines from 2-Aminobenzonitrile, Anilines and Formic Acid or Benzaldehydes.CHEMINFORM, Issue 13 2001Wojciech Szczepankiewicz Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Photoelectrochemical Behavior of Nanostructured WO3 Thin-Film Electrodes: The Oxidation of Formic AcidCHEMPHYSCHEM, Issue 12 2006Damián Monllor-Satoca Abstract Nanostructured tungsten trioxide thin-film electrodes are prepared on conducting glass substrates by either potentiostatic electrodeposition from aqueous solutions of peroxotungstic acid or direct deposition of WO3 slurries. Once treated thermally in air at 450,°C, the electrodes are found to be composed of monoclinic WO3 grains with a particle size around 30,40 nm. The photoelectrochemical behavior of these electrodes in 1,M HClO4 apparently reveals a low degree of electron,hole recombination. Upon addition of formic acid, the electrode showed the current multiplication phenomenon together with a shift of the photocurrent onset potential toward less positive values. Photoelectrochemical experiments devised on the basis of a kinetic model reported recently [I. Mora-Seró, T. Lana-Villarreal, J. Bisquert, A. Pitarch, R. Gómez, P. Salvador, J. Phys. Chem. B2005, 109, 3371] showed that an interfacial mechanism of inelastic, direct hole transfer takes place in the photooxidation of formic acid. This behavior is attributed to the tendency of formic acid molecules to be specifically adsorbed on the WO3 nanoparticles, as evidenced by attenuated total reflection infrared spectroscopy. [source] Breakthroughs in Hydrogen Storage,Formic Acid as a Sustainable Storage Material for HydrogenCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 10 2008Ferenc Joó Prof. A boost for fuel cells: Recent results suggest that formic acid is a convenient hydrogen-storage material: its decomposition yields CO-free hydrogen while the co-produced carbon dioxide can be hydrogenated back to formic acid. The hydrogen generated in this way is suitable for fuel cell applications. [source] Simple method for determination of cocaine and main metabolites in urine by CE coupled to MSELECTROPHORESIS, Issue 12 2009José Luiz da Costa Abstract In this work, a simple method for the simultaneous determination of cocaine (COC) and five COC metabolites (benzoylecgonine, cocaethylene (CET), anhydroecgonine, anhydroecgonine methyl ester and ecgonine methyl ester) in human urine using CE coupled to MS via electrospray ionization (CE-ESI-MS) was developed and validated. Formic acid at 1,mol/L concentration was used as electrolyte whereas formic acid at 0.05,mol/L concentration in 1:1 methanol:water composed the coaxial sheath liquid at the ESI nozzle. The developed method presented good linearity in the dynamic range from 250,ng/mL to 5000,ng/mL (coefficient of determination greater than 0.98 for all compounds). LODs (signal-to-noise ratio of 3) were 100,ng/mL for COC and CET and 250,ng/mL for the other studied metabolites whereas LOQ's (signal-to-noise ratio of 10) were 250,ng/mL for COC and CET and 500,ng/mL for all other compounds. Intra-day precision and recovery tests estimated at three different concentration levels (500, 1500 and 5000,ng/mL) provided RSD lower than 10% (except anhydroecgonine, 18% RSD) and recoveries from 83,109% for all analytes. The method was successfully applied to real cases. For the positive urine samples, the presence of COC and its metabolites was further confirmed by MS/MS experiments. [source] Mitochondrial impacts of insecticidal formate esters in insecticide-resistant and insecticide-susceptible Drosophila melanogasterPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 6 2009Cheol Song Abstract BACKGROUND: Previous research on insecticidal formate esters in flies and mosquitoes has documented toxicity profiles, metabolism characteristics and neurological impacts. The research presented here investigated mitochondrial impacts of insecticidal formate esters and their hydrolyzed metabolite formic acid in the model dipteran insect Drosophila melanogaster Meig. These studies compared two Drosophila strains: an insecticide-susceptible strain (Canton-S) and a strain resistant by cytochrome P450 overexpression (Hikone-R). RESULTS: In initial studies investigating inhibition of mitochondrial cytochrome c oxidase, two proven insecticidal materials (hydramethylnon and sodium cyanide) caused significant inhibition. However, for insecticidal formate esters and formic acid, no significant inhibition was identified in either fly strain. Mitochondrial impacts of formate esters were then investigated further by tracking toxicant-induced cytochrome c release from mitochondria into the cytoplasm, a biomarker of apoptosis and neurological dysfunction. Formic acid and three positive control treatments (rotenone, antimycin A and sodium cyanide) induced cytochrome c release, verifying that formic acid is capable of causing mitochondrial disruption. However, when comparing formate ester hydrolysis and cytochrome c release between Drosophila strains, formic acid liberation was only weakly correlated with cytochrome c release in the susceptible Canton-S strain (r2 = 0.70). The resistant Hikone-R strain showed no correlation (r2 < 0.0001) between formate ester hydrolysis and cytochrome c release. CONCLUSION: The findings of this study provide confirmation of mitochondrial impacts by insecticidal formate esters and suggest links between mitochondrial disruption, respiratory inhibition, apoptosis and formate-ester-induced neurotoxicity. Copyright © 2009 Society of Chemical Industry [source] Catalytic cleavage of methyl oleate or oleic acidEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 1 2010Angela Köckritz Abstract Different reaction pathways are discussed for the Os-catalyzed oxidation of methyl oleate and oleic acid using O2/aldehyde as oxidation system. Monomethyl azelate and pelargonic acid were the main products obtained in yields of approximately 50,70% starting from methyl oleate. Besides, varying amounts of methyl 9,10-epoxystearate and methyl 9,10-dihydroxystearate were found as by-products. Azelaic acid and pelargonic acid were obtained exclusively from oleic acid used as reactant. Some mechanistic considerations led to the conclusion that the observed products are formed in parallel reaction paths. The effective oxidant for the scission of the C=C double bond seems to be very likely an in situ formed peracid generated by Os-catalysis from O2/aldehyde. Additional investigations concerning the cleavage of oleic acid and methyl oleate with in situ formed performic acid from H2O2/formic acid corroborate this assumption. [source] Development of a multi-mycotoxin liquid chromatography/tandem mass spectrometry method for sweet pepper analysisRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 1 2009Sofie Monbaliu A multi-mycotoxin method was developed for the simultaneous determination of trichothecenes (nivalenol, deoxynivalenol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, neosolaniol, fusarenon-X, diacetoxyscirpenol, HT-2 toxin, T-2 toxin), aflatoxins (aflatoxin-B1, aflatoxin-B2, aflatoxin-G1 and aflatoxin-G2), Alternaria toxins (alternariol, alternariol methyl ether and altenuene), fumonisins (fumonisin-B1, fumonisin-B2 and fumonisin-B3), ochratoxin A, zearalenone, beauvericin and sterigmatocystin in sweet pepper. Sweet pepper was extracted with ethyl acetate/formic acid (99:1, v/v). After splitting up the extract, two-thirds of the extract was cleaned up using an aminopropyl column followed by an octadecyl column. The remaining part was cleaned up using a strong anion-exchange column. After recombination of both cleaned parts of the sample extract, the combined solvents were evaporated and the residue was dissolved in mobile phase; 20,µL was injected into the chromatographic system, so only one run was used to separate and detect the mycotoxins in positive electrospray ionization using selected reaction monitoring. The samples were analyzed with a Micromass Quattro Micro triple quadrupole mass spectrometer (Waters, Milford, MA, USA). The mobile phase consisted of variable mixtures of water and methanol, 1% acetic acid and 5,mM ammonium acetate. The limits of detection of the multi-mycotoxin method varied from 0.32,µg.kg,1 to 42.48,µg.kg,1. The multi-mycotoxin liquid chromatography/tandem mass spectrometry (LC/MS/MS) method fulfilled the method performance criteria required by the Commission Regulation (EC) No 401/2006. Sweet peppers inoculated by Fusarium species were analyzed using the developed method. Beauvericin (9,484,µg.kg,1) and fumonisins (fumonisin-B1 up to 4330,µg.kg,1, fumonisin-B2 up to 4900,µg.kg,1, and fumonisin-B3 up to 299,µg.kg,1) were detected. Copyright © 2008 John Wiley & Sons, Ltd. [source] Epoxidation of Jatropha (Jatropha curcas) oil by peroxyacidsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2010Vaibhav V. Goud Abstract Jatropha (Jatropha curcas) oil with iodine value 104 g I2/100 g, and containing 44.7% oleic acid and 31.4% linoleic acid, was epoxidised in situ with hydrogen peroxide (30%) and acetic/formic acid in the presence of catalytic amounts of sulphuric acid. We have compared the kinetics of epoxidation of jatropha oil (JO) by peroxyacetic and peroxyformic acids, in or without toluene at 30, 50, 70, and 85 °C. The effects of temperature and various mole ratios on epoxidation rate, oxirane ring stability, and iodine value of the epoxidised oil were studied, and optimum conditions were established. The rate constants for epoxidation of JO were found to be in the range 0.22,69.4 × 10,6 l.mol,1.s,1 and activation energies were found to be 64.46 KJ.mol,1, 72 KJ.mol,1, 59 KJ.mol,1, 68.24 KJ.mol,1, for peroxyacetic and peroxyformic acids in or without toluene, respectively. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] (.+-.)-cis-(6-Ethyl-tetrahydropyran-2-yl)-formic Acid: A Novel Substance with Antinociceptive Properties.CHEMINFORM, Issue 29 2004L. S. M. Miranda Abstract For Abstract see ChemInform Abstract in Full Text. [source] Simultaneous determination of six non-polar heterocyclic amines in meat samples by supercritical fluid extraction,capillary electrophoresis under fluorimetric detectionELECTROPHORESIS, Issue 13 2010Fernando De Andrés Abstract A novel, sensitive and selective method for the separation and quantification of a group of non-polar heterocyclic amines (9H-pyrido-[3,4-b] indole, norharmane; 1-methyl-9H-pyrido-[3,4-b] indole, harmane; 2-amino-9H-pyrido-[2,3-b] indole, A,C; 2-amino-3-methyl-9H-pyrido-[2,3-b] indole, MeA,C; 3-amino-1,4-dimethyl-5H-pyrido-[4,3-b] indole, Trp-P-1 and 3-amino-1-methyl-5H-pyrido-[4,3-b] indole, Trp-P-2) in commercial meat samples has been developed. This methodology is faster than others previously described. The method is based on the combination of a supercritical fluid extraction procedure, followed by the analysis of the extracted plug by CE with fluorescence detection. The supercritical fluid extraction procedure was optimized for the clean-up of the samples and the extraction of the analytes. For the electrophoretic separation, the effect of composition, pH and concentration of buffer, organic modifier content, pressure and time of injection, capillary temperature and voltage applied were studied. A 10,mmol/L formic acid,ammonium formate,ACN (10%, v/v) solution at pH 1.5 was selected as the running electrolyte. With 5-s hydrodynamic injection, linear responses in the range from 100 to 1000,ng/mL and detection limits ranging from 15.9 to 28.1,ng/mL were obtained for different amines in less than 13,min. ACN,water (1:1 in volume) was used as a sample solvent. Fluorescence detection enhances the sensitivity and avoids interferences coming from non-fluorescent compounds present in the matrices of the sample extracts. [source] CEC-ESI ion trap MS of multiple drugs of abuseELECTROPHORESIS, Issue 7 2010Zeineb Aturki Abstract This article describes a method for the separation and determination of nine drugs of abuse in human urine, including amphetamines, cocaine, codeine, heroin and morphine. This method was based on SPE on a strong cation exchange cartridge followed by CEC-MS. The CEC experiments were performed in fused silica capillaries (100,,m×30,cm) packed with a 3,,m cyano derivatized silica stationary phase. A laboratory-made liquid junction interface was used for CEC-MS coupling. The outlet capillary column was connected with an emitter tip that was positioned in front of the MS orifice. A stable electrospray was produced at nanoliter per minute flow rates applying a hydrostatic pressure (few kPa) to the interface. The coupling of packed CEC columns with mass spectrometer as detector, using a liquid junction interface, provided several advantages such as better sensitivity, low dead volume and independent control of the conditions used for CEC separation and ESI analysis. For this purpose, preliminary experiments were carried out in CEC-UV to optimize the proper mobile phase for CEC analysis. Good separation efficiency was achieved for almost all compounds, using a mixture containing ACN and 25,mM ammonium formate buffer at pH 3 (30:70, v/v), as mobile phase and applying a voltage of 12,kV. ESI ion-trap MS detection was performed in the positive ionization mode. A spray liquid, composed by methanol,water (80:20, v/v) and 1% formic acid, was delivered at a nano-flow rate of ,200,nL/min. Under optimized CEC-ESI-MS conditions, separation of the investigated drugs was performed within 13,min. CEC-MS and CEC-MS2 spectra were obtained by providing the unambiguous confirmation of these drugs in urine samples. Method precision was determined with RSDs values ,3.3% for retention times and ,16.3% for peak areas in both intra-day and day-to-day experiments. LODs were established between 0.78 and 3.12,ng/mL for all compounds. Linearity was satisfactory in the concentration range of interest for all compounds (r2,0.995). The developed CEC-MS method was then applied to the analysis of drugs of abuse in spiked urine samples, obtaining recovery data in the range 80,95%. [source] CE-MS method development for peptides analysis, especially hepcidin, an iron metabolism markerELECTROPHORESIS, Issue 15 2009Gaëlle B. Martin Abstract A method for the resolution of a peptides mixture including hepcidin-25, an iron metabolism marker, was developed by CE-ESI-MS. Several strategies were tested to optimize peptide separation, such as the addition of cyclodextrins or organic solvents in the BGE or the use of coated capillaries. Best results in terms of resolution, symmetry and efficiency were obtained with a BGE made of 500,mM ammonium acetate pH 4.5/ACN 70:30,v/v. Using the methodology of experimental design, BGE concentration, sheath liquid composition and MS-coupling parameters were then optimized in order to obtain the best signal intensity for hepcidin. Finally, a 225,mM BGE and a sheath liquid composed of isopropanol/water 80:20,v/v containing 0.5%,v/v formic acid were selected as it constitutes the best compromise for selectivity, peak shape and sensitivity. [source] Simple method for determination of cocaine and main metabolites in urine by CE coupled to MSELECTROPHORESIS, Issue 12 2009José Luiz da Costa Abstract In this work, a simple method for the simultaneous determination of cocaine (COC) and five COC metabolites (benzoylecgonine, cocaethylene (CET), anhydroecgonine, anhydroecgonine methyl ester and ecgonine methyl ester) in human urine using CE coupled to MS via electrospray ionization (CE-ESI-MS) was developed and validated. Formic acid at 1,mol/L concentration was used as electrolyte whereas formic acid at 0.05,mol/L concentration in 1:1 methanol:water composed the coaxial sheath liquid at the ESI nozzle. The developed method presented good linearity in the dynamic range from 250,ng/mL to 5000,ng/mL (coefficient of determination greater than 0.98 for all compounds). LODs (signal-to-noise ratio of 3) were 100,ng/mL for COC and CET and 250,ng/mL for the other studied metabolites whereas LOQ's (signal-to-noise ratio of 10) were 250,ng/mL for COC and CET and 500,ng/mL for all other compounds. Intra-day precision and recovery tests estimated at three different concentration levels (500, 1500 and 5000,ng/mL) provided RSD lower than 10% (except anhydroecgonine, 18% RSD) and recoveries from 83,109% for all analytes. The method was successfully applied to real cases. For the positive urine samples, the presence of COC and its metabolites was further confirmed by MS/MS experiments. [source] Comparative metabolite profiling of carboxylic acids in rat urine by CE-ESI MS/MS through positively pre-charged and 2H-coded derivatizationELECTROPHORESIS, Issue 22 2008Wen-Chu Yang Abstract A new approach to the selective comparative metabolite profiling of carboxylic acids in rat urine was established using CE-MS and a method for positively pre-charged and 2H-coded derivatization. Novel derivatizing reagents, N -alkyl-4-aminomethyl-pyridinum iodide (alkyl=butyl, butyl-d9 or hexyl), containing quaternary amine and stable-isotope atoms (deuterium), were introduced for the derivatization of carboxylic acids. CE separation in positive polarity showed high reproducibility (0.99,1.32% RSD of migration time) and eliminated problems with capillary coating known in CE-MS anion analyses. Essentially complete ionization and increased hydrophobicity after the derivatization also enhanced MS detection sensitivity (e.g. formic acid was detected at 0.5,pg). Simultaneous derivatization of one sample using two structurally similar reagents, N -butyl-4-aminomethyl-pyridinum iodide (BAMP) and N -hexyl-4-aminomethyl-pyridinum iodide, provided additional information for recognizing a carboxylic acid in an unknown sample. Moreover, characteristic fragmentation acquired by online CE-MS/MS allowed for identification and categorization of carboxylic acids. Applying this method on rat urine, we found 59 ions matching the characteristic patterns of carboxylic acids. From these 59, 32 ions were positively identified and confirmed with standards. For comparative analysis, 24 standard carboxylic acids were derivatized by chemically identical but isotopically distinct BAMP and N -butyl-d9-4-aminomethyl-pyridinium iodide, and their derivatization limits and linearity ranges were determined. Comparative analysis was also performed on two individual urine samples derivatized with BAMP and N -butyl-d9-4-aminomethyl-pyridinium iodide. The metabolite profiling variation between these two samples was clearly visualized. [source] Separation of multiphosphorylated peptide isomers by CZEELECTROPHORESIS, Issue 21 2008Marika V. Muetzelburg Abstract A separation of mono, doubly and triply phosphorylated isomers was developed with CZE with an aqueous electrolyte containing 3.9,mol/L formic acid and 30%,v/v trifluoroethanol. Thus a mixture of ten phosphopeptides corresponding to the human tau sequence 226,240 was separated within 70,min. Although peptides with different phosphorylation degrees, i.e. 0,3 phosphate groups, were well separated, some of the phosphopeptide isomers containing one or two phosphate groups were only partially separated. The electrolyte system is compatible with both MALDI- and ESI-MS, allowing a direct coupling, and thus could have some interesting applications in proteomics. [source] Capillary electrophoresis-time of flight-mass spectrometry using noncovalently bilayer-coated capillaries for the analysis of amino acids in human urineELECTROPHORESIS, Issue 12 2008Rawi Ramautar Abstract A capillary electrophoresis-time of flight-mass spectrometry (CE-TOF-MS) method for the analysis of amino acids in human urine was developed. Capillaries noncovalently coated with a bilayer of Polybrene (PB) and poly(vinyl sulfonate) (PVS) provided a considerable EOF at low pH, thus facilitating the fast separation of amino acids using a BGE of 1,M formic acid (pH,1.8). The PB,PVS coating proved to be very consistent yielding stable CE-MS patterns of amino acids in urine with favorable migration time repeatability (RSDs <2%). The relatively low sample loading capacity of CE was circumvented by an in-capillary preconcentration step based on pH-mediated stacking allowing 100-nL sample injection (i.e. ca. 4% of capillary volume). As a result, LODs for amino acids were down to 20,nM while achieving satisfactory separation efficiencies. Preliminary validation of the method with urine samples showed good linear responses for the amino acids (R2 >0.99), and RSDs for peak areas were <10%. Special attention was paid to the influence of matrix effects on the quantification of amino acids. The magnitude of ion suppression by the matrix was similar for different urine samples. The CE-TOF-MS method was used for the analysis of urine samples of patients with urinary tract infection (UTI). Concentrations of a subset of amino acids were determined and compared with concentrations in urine of healthy controls. Furthermore, partial least squares,discriminant analysis (PLS,DA) of the CE-TOF-MS dataset in the 50,450,m/z region showed a distinctive grouping of the UTI samples and the control samples. Examination of score and loadings plot revealed a number of compounds, including phenylalanine, to be responsible for grouping of the samples. Thus, the CE-TOF-MS method shows good potential for the screening of body fluids based on the analysis of endogenous low-molecular weight metabolites such as amino acids and related compounds. [source] Development of a new method for analysis of Sudan dyes by pressurized CEC with amperometric detectionELECTROPHORESIS, Issue 11 2007Shaofeng Liu Abstract A new analytical method, pressurized CEC (pCEC) with amperometric detection (AD) using 1.5,,m RP nonporous silica packed columns has been developed for the rapid separation and determination of four Sudan dyes in hot chilli. The influence of several experimental parameters on the retention behavior has been investigated. The electrochemical oxidation of Sudans I,IV separated by pCEC can be reliably monitored with a carbon electrode at +0.95,V (vs. Ag/AgCl). Fast and efficient separation of the analytes was achieved within 7,min by pCEC under the optimum conditions with an ACN/water (95:5%) mobile phase containing formic acid (pH,4.3), 5% acetone and 0.002% triethylamine using a separation voltage of 12,kV. The detection limits for four Sudan dyes ranged from 8.0,×,10,7 to 1.2,×,10,6,mol/L. To evaluate the feasibility and reliability of this method, the proposed pCEC-AD method was further demonstrated with hot chilli samples spiked with Sudan dyes. [source] A generic approach to the impurity profiling of drugs using standardised and independent capillary zone electrophoresis methods coupled to electrospray ionisation mass spectrometryELECTROPHORESIS, Issue 9 2005Aurélie Vassort Abstract Three standardised, capillary zone electrophoresis-electrospray ionisation mass spectrometry (CZE-ESI-MS) methods were developed for the analysis of six drug candidates and their respective process-related impurities comprising a total of 22 analytes with a range of functional groups and lipophilicities. The selected backround electrolyte conditions were found to be: 60/40 v/v 10 mM ammonium formate pH 3.5/organic, 60/40 v/v 10 mM ammonium acetate pH 7.0/organic and 10 mM piperidine, pH 10.5, where the organic solvent is 50/50 v/v methanol/acetonitrile. The coaxial sheath flow consisted of either 0.1% v/v formic acid in 50/50 v/v methanol/water, or 10 mM ammonium acetate in 50/50 v/v methanol/water, depending on the mixture being analysed. Factor analysis and informational theory were used to quantify the orthogonality of the methods and predict their complementarities. The three selected CZE-ESI-MS methods allowed the identification of 21 out of 22 of all the drug candidates and their process-related impurities and provided orthogonality with four established high-performance liquid chromatography-mass spectrometry (HPLC-MS) methods. These methodologies therefore form the basis of a generic approach to impurity profiling of pharmaceutical drug candidates and can be applied with little or no analytical method development, thereby offering significant resource and time savings. [source] Analysis of the glucosinolate pattern of Arabidopsis thaliana seeds by capillary zone electrophoresis coupled to electrospray ionization-mass spectrometryELECTROPHORESIS, Issue 7-8 2005Gerhard Bringmann Abstract An easy and rapid method for the analysis of intact, non-desulfated glucosinolates by capillary zone electrophoresis (CZE) coupled to electrospray ionization-time of flight-mass spectrometry (ESI-TOF-MS) is described. Surprisingly, an electrolyte and a sheath liquid based on formic acid provided the best results. In this strongly acidic system, the glucosinolates were separated and detected as anions, resulting in an excellent selectivity. Thus, crude plant extracts could be analyzed without any interference of matrix constituents. The sensitivity together with mass accuracy and true isotopic pattern of the TOF-MS allowed identification of a broad series of glucosinolates in Arabidopsis thaliana seeds. [source] Electrospun Silk Fibroin Mats for Tissue EngineeringENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 3 2008A. Alessandrino Abstract Processing Silk Fibroin (SF) with electrospinning (ES) offers a very attractive opportunity for producing a variety of 2D and 3D matrices with great potential for tissue regeneration and repair due to the superior biocompatibility and mechanical properties of SF. Different combinations of ES parameters were explored to investigate the best experimental set-up related to the dimension and uniformity of the fibers in the electrospun silk fibroin (ES-SF) mats. Using SEM it was found that the ES-SF mats contain uniform fibers with a diameter in the nanometric range obtained by electrospinning a 7.5,% w/v SF solution in formic acid, with an electric field of 2.4,kV/cm and a spinneret-collector distance of 10,cm. FT-IR and DSC analyses were performed to investigate the structure of the ES-SF mats before and after immersion in methanol for different times (5, 10, and 15,min). The methanol treatment was able to promote the crystallization of SF by conformational transition of random coil and other poorly ordered conformations (turns and bends) to the ,-sheet structure. The degree of crystallinity was enhanced as shown by the trend of both the FT-IR crystallinity index and the melting/decomposition peak temperature (from DSC). To study the cytocompatibility of ES-SF mats, tests with L929 murine fibroblasts were carried out. Samples were seeded with the cells and incubated for 1, 3, and 7,days at 37,°C. At each time point, SEM investigations and Alamar blue tests were performed. The SEM images showed cell adhesion and proliferation just after 1,day and cell confluence at 7,days. Alamar blue test demonstrated that there were very low differences between cell viability on ES-SF mats and the tissue culture plastic control. [source] Extraction and purification of the zwitterions cylindrospermopsin and deoxycylindrospermopsin from Cylindrospermopsis raciborskiiENVIRONMENTAL TOXICOLOGY, Issue 5 2001R. L. G. Norris Abstract The hepatotoxin cylindrospermopsin (CYN) has been isolated from the cyanobacterium Cylindrospermopsis raciborskii (C. raci.). Efforts to study this toxin have been hampered by the time-consuming requirement to extract it from cultures of the organism. It is usually extracted from lyophilized cells collected from a laboratory culture. Our preliminary work suggested far more of the toxin is available in solution in the culture media than in the cells collected. We have therefore investigated the use of commercially available solid phase extraction sorbents to extract CYN from culture media in which C. raci. has been grown. A range of reverse phase and ion-exchange sorbents were tested across a range of pHs for their ability to retain CYN without success. Subsequently, graphitized carbon cartridges were found to retain CYN strongly. Elution with 5% formic acid in methanol allowed the CYN to be regained for final purification by HPLC. Deoxy-CYN, an analog of CYN can also be extracted using this procedure. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 391,396, 2001 [source] Drastic Solid-State Fluorescence Enhancement Behaviour of Phenanthro[9,10- d]imidazole-Type Fluorescent Hosts upon Inclusion of Carboxylic AcidsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 34 2009Yousuke Ooyama Abstract The crystals of phenanthro[9,10- d]imidazole-type fluorescent host 1 exhibit drastic fluorescence enhancement behaviour with a redshift in the emission maximum upon enclathration of various carboxylic acids such as formic acid, acetic acid and propionic acid. The optical changes are greatly dependent on the identity of the enclathrated carboxylic acids. The fluorescent clathrate compounds are formed not only by cocrystallization from carboxylic acid solutions but also by solid (fluorescent host),gas (carboxylic acid vapour) contact. Furthermore, when the acetic acid inclusion crystals are exposed to propionic acid vapour, acetic acid is gradually replaced by propionic acid. The guest exchange of the inclusion crystals was accompanied with colour and fluorescent intensity changes. The X-ray structural analyses of the guest-free and carboxylic acid inclusion compounds demonstrated that the destructions of the ,,, interactions, and the intermolecular hydrogen bonds binding fluorophores were induced by the enclathrated carboxylic acid molecules. Moreover, the imidazole ring of the host is protonated by the enclathrated carboxylic acid proton. On the basis of the spectroscopic data and the crystal structures, the effects of the enclathrated carboxylic acid on the solid-state photophysical properties of the clathrate compounds are discussed.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Heterointegration of Pt/Si/Ag Nanowire Photodiodes and Their Photocatalytic PropertiesADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Yongquan Qu Abstract Photocatalyst mediated photoelectrochemical processes can make use of the photogenerated electrons and holes onsite for photocatalytic redox reactions, and enable the harness and conversion of solar energy into chemical energy, in analogy to natural photosynthesis. However, the photocatalysts available to date are limited by either poor efficiency in the visible light range or insufficient photoelectrochemical stability. Here, it is shown that a Pt/Si/Ag nanowire heterostructure can be rationally synthesized to integrate a nanoscale metal-semiconductor Schottky diode encased in a protective insulating shell with two exposed metal catalysts. The synthesis of Pt/Si/Ag nanowire diodes involves a scalable process including the formation of silicon nanowire array through wet chemical etching, electrodeposition of platinum and photoreduction of silver. The Pt/Si/Ag diodes exhibit highly efficient photocatalytic activity for a wide range of applications including environmental remediation and solar fuel production in the visible range. In this article, photodegradation of indigo carmine and 4-nitrophenol are used to evaluate the photoactivity of Pt/Si/Ag diodes. The Pt/Si/Ag diodes also show high activity for photoconversion of formic acid into carbon dioxide and hydrogen. [source] Heterointegration of Pt/Si/Ag Nanowire Photodiodes and Their Photocatalytic PropertiesADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Yongquan Qu Abstract Photocatalyst mediated photoelectrochemical processes can make use of the photogenerated electrons and holes onsite for photocatalytic redox reactions, and enable the harness and conversion of solar energy into chemical energy, in analogy to natural photosynthesis. However, the photocatalysts available to date are limited by either poor efficiency in the visible light range or insufficient photoelectrochemical stability. Here, it is shown that a Pt/Si/Ag nanowire heterostructure can be rationally synthesized to integrate a nanoscale metal-semiconductor Schottky diode encased in a protective insulating shell with two exposed metal catalysts. The synthesis of Pt/Si/Ag nanowire diodes involves a scalable process including the formation of silicon nanowire array through wet chemical etching, electrodeposition of platinum and photoreduction of silver. The Pt/Si/Ag diodes exhibit highly efficient photocatalytic activity for a wide range of applications including environmental remediation and solar fuel production in the visible range. In this article, photodegradation of indigo carmine and 4-nitrophenol are used to evaluate the photoactivity of Pt/Si/Ag diodes. The Pt/Si/Ag diodes also show high activity for photoconversion of formic acid into carbon dioxide and hydrogen. [source] Variation in essential oil composition of rose-scented geranium (Pelargonium sp.) distilled by different distillation techniques,FLAVOUR AND FRAGRANCE JOURNAL, Issue 2 2005Kiran G. D. Babu Abstract The rose-scented geranium (Pelargonium sp.) cultivar ,Kelkar', grown in the agroclimatic conditions of the western Himalayas, was processed by various hydrodistillation methods, which revealed that water distillation of the herb gave a higher oil yield (0.16,0.22%) than the water,steam distillation (0.09,0.12%) and steam distillation methods (0.06,0.18%). The samples were analysed by GC and GC,MS to study and compare the essential oil compositions which revealed that the oil distilled by the water,steam distillation method contained a higher content of monoterpene hydrocarbons (1.7%), followed by steam distillation without cohobation and without recycling (1.5%). A higher content of sesquiterpene hydrocarbons (4.4%) was found in cumulative oil followed by ,direct oil' (4.2%) obtained by steam distillation with cohobation and without recycling of hydrosol, followed by the water,steam distillation method (3.4%). ,Decanted oil', recovered from redistilling the hydrosol obtained by steam distillation with cohobation and without recycling, contained maximum monoterpene cyclic ethers (1.1%) and carbonyl content (9.9%), closely followed by water,steam distillation method (1.1% and 7.2%, respectively). Steam distillation without cohobation and without recycling of hydrosol yielded essential oil with a higher percentage of esters (21.1%), followed by ,direct oil' (16.6%). Lower ester content (5.3%) was noticed in ,decanted oil', followed by oil distilled by steam distillation with cohobation and with recycling (11.8%) and oil distilled in a Clevenger apparatus by the water distillation method (12.2%), whereas maximum total alcohols were found in the ,decanted oil' (75.1%), followed by oil from the Clevenger apparatus (72.8%) and steam distillation with cohobation and with recycling (69.1%). A lower alcohol content was found in the ,direct oil' (55.2%) closely followed by ,cumulative oil' (55.8%). The variation in total alcohol and ester contents in geranium oil samples, distilled by using different processing techniques on pilot scale distillation, is mainly due to hydrolysis of some volatile constituents. This was further supported by acid values of the oils, along with other physicochemical properties, such as speci,c gravity, optical rotation, refractive index, solubility in alcohol, ester value with cold and hot methods, estimation of ester content as geranyl formate and geranyl tiglate, ester number after acetylation, and ester number after formylation with aceto-formic acid and formic acid. Methods have been standardized and proposed for distillations of speci,c quality, e.g. ester-rich and alcohol-rich geranium oils, to meet different requirements of the industry. Copyright © 2004 John Wiley & Sons, Ltd. [source] The effect of additives in silages of pure timothy and timothy mixed with red clover on chemical composition and in vitro rumen fermentation characteristicsGRASS & FORAGE SCIENCE, Issue 3 2003M. Hetta Abstract The aim was to compare the effects of additives on direct cut silages of pure timothy and timothy mixed with tetraploid red clover. First and second growth cuts were ensiled during three consecutive years, 1994, 1995 and 1996, either without any additive or with the addition of formic acid, or lactic acid bacteria in combination with molasses. Effects of the additives on the degradation characteristics of the herbage and the silages were analysed using an automatic in vitro gas production (GP) technique. At the end of the in vitro procedures, organic matter and neutral-detergent fibre (NDF) degradabilities were determined. The tetraploid red clover persisted in the leys during the 3 years and was the dominant species at the second growth in the mixed leys. The herbage from the mixed crops had lower dry-matter contents, higher crude protein concentrations and higher buffering capacity compared with the pure timothy at both cuts. In general, the additives reduced pH, and the concentrations of ammonium-N and acetic acid in the silages. The treated silages had a more rapid faster GP in both crops. The silages from the mixed crop benefited more from the additives compared with the grass silages. The additives affected the soluble fractions as well as the NDF degradability of the silages of the mixed crop more than those fractions of the grass silages. The addition of molasses in combination with a commercial inocula resulted in increased production of lactic acid and ethanol in silages from both crops. The silages without additives could not meet the requirements for good silages according to the standards of the Swedish dairy industry. [source] Photocatalytic reduction of carbonates and formation of some energy rich systems in the presence of Toluidine BlueINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 2 2001Sarita Jain Abstract Aqueous sodium and potassium carbonates have been photoreduced in the presence of Toluidine Blue solution (which is also the photocatalyst). The photocatalytic formation of formic acid and formaldehyde was measured spectrophotometrically using Nash reagent. The effect of variation of various parameters like pH, amount of photocatalyst (Toluidine Blue concentration), concentration of Na2CO3 and K2CO3, light intensity, etc., on the yield of photoproducts was also investigated. A tentative mechanism for this reduction has been proposed. Copyright © 2001 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||||||||||||||