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formic acid

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https://www.readbyqxmd.com/read/28319777/analysis-of-the-effect-of-temperature-and-reaction-time-on-yields-compositions-and-oil-quality-in-catalytic-and-non-catalytic-lignin-solvolysis-in-a-formic-acid-water-media-using-experimental-design
#1
Mikel Oregui Bengoechea, Nemanja Miletíc, Mari H Vogt, Pedro L Arias, Tanja Barth
The catalytic solvolysis of Norway spruce (Picea abies L.) lignin in a formic acid/water media was explored at different temperatures and reaction times (283-397°C and 21-700min, respectively). Non-catalyzed experiments were compared with the effect of three different type of bifunctional catalysts (Pd/Al2O3, Rh/Al2O3 and Ru/Al2O3) and a solid Lewis acid (γ-Al2O3). We demonstrated that surface response methodology (RSM) and principal component analysis (PCA) were an adequate tool to: (i) evaluate the effect of the catalysts, temperature and reaction time in the oil yield, oil quality (H/C and O/C ratios, and Mw) and composition of the oil, (ii) establish the differences and/or similarities between the three bifunctional catalyst and (iii) to determine the role of the noble metal and the alumina support in the reaction system...
March 1, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28318564/comparing-the-selectivity-and-chiral-separation-of-d-and-l-fluorenylmethyloxycarbonyl-chloride-fmoc-protected-amino-acids-in-analytical-high-performance-liquid-chromatography-and-supercritical-fluid-chromatography-evaluating-throughput-economic-and-environmental
#2
C M Vera, D Shock, G R Dennis, W Farrell, R A Shalliker
The chiral separation of d- and l- FMOC amino acids was undertaken using the Lux Cellulose-1 polysaccharide based chiral column in HPLC (normal phase and reverse phase) and SFC conditions. This was done to compare the relative selectivity and separation between the three separation modes and to evaluate the potential benefits of SFC separations with regards to resolution, throughput, economic and environmental impact. It was established that the separation of d- and l- FMOC amino acids in SFC displayed behaviours that were similar to both normal phase and reversed phase, rather than distinctly one or the other...
February 16, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28318266/pd-nanoparticles-coupled-to-wo2-72-nanorods-for-enhanced-electrochemical-oxidation-of-formic-acid
#3
Zheng Xi, Daniel P Erdosy, Adriana Mendoza-Garcia, Paul N Duchesne, Junrui Li, Michelle Muzzio, Qing Li, Peng Zhang, Shouheng Sun
We synthesize a new type of hybrid Pd/WO2.72 structure with 5 nm Pd nanoparticles (NPs) anchored on 50 x 5 nm WO2.72 nanorods (NRs). The strong Pd-WO2.72 coupling results in the lattice expansion of Pd from 0.23 nm to 0.27 nm and the decrease of Pd surface electron density. As a result, the Pd/WO2.72 shows much enhanced catalysis towards electrochemical oxidation of formic acid in 0.1 M HClO4 - it has a mass activity of ~1600 mA/mgPd in a broad potential range of 0.4-0.85 V (vs. RHE) and shows no obvious activity loss after a 12 h chronoamperometry test at 0...
March 20, 2017: Nano Letters
https://www.readbyqxmd.com/read/28317741/a-novel-method-for-the-quality-control-of-saffron-through-the-simultaneous-analysis-of-authenticity-and-adulteration-markers-by-liquid-chromatography-quadrupole-time-of-flight-mass-spectrometry
#4
Miguel Guijarro-Díez, María Castro-Puyana, Antonio Luis Crego, María Luisa Marina
A liquid chromatography-(quadrupole-time of flight)-mass spectrometry methodology was developed to assess the authenticity of saffron through the analysis of a group of kaempferol derivatives recently proposed as novel authenticity markers as a result of a metabolomic study of saffron (kaempferol 3-O-glucoside, kaempferol 3-O-sophoroside, kaempferol 3,7-O-diglucoside, kaempferol 3,7,4'-O-triglucoside, kaempferol 3-O-sophoroside-7-O-glucoside). Geniposide was also studied as an adulteration marker of saffron with gardenia...
August 1, 2017: Food Chemistry
https://www.readbyqxmd.com/read/28317144/uhplc-ms-ms-method-for-the-determination-of-omarigliptin-in-rat-plasma-and-its-application-to-a-pharmacokinetic-study-in-rats
#5
Meng-Fang Li, Xiao-Xia Hu, Ai-Qun Ma
Omarigliptin is a novel long-acting DPP-4 inhibitor used for the treatment of T2DM. In this work, a sensitive and selective UHPLC-MS/MS method was developed and validated for determination of omarigliptin in rat plasma. Sample preparation was performed by protein precipitation with acetonitrile. Chromatographic separation of analytes was achieved on a RRHD Eclipse Plus C18 column (2.1 × 50 mm, 1.8 µ), using gradient mobile phase (0.1% formic acid-acetonitrile) at a flow rate of 0.4 mL/min. Detection was performed in multiple reaction monitoring mode, with target fragment ions m/z 399...
March 19, 2017: Biomedical Chromatography: BMC
https://www.readbyqxmd.com/read/28317135/free-mycophenolic-acid-determination-in-human-plasma-ultrafiltrate-by-a-validated-liquid-chromatography-tandem-mass-spectrometry-method
#6
Paulina Łuszczyńska, Tomasz Pawiński, Paweł K Kunicki, Katarzyna Sikorska, Ryszard Marszałek
OBJECTIVES: The aim of this study was to develop and fully validate LC-MS/MS method for free mycophenolic acid (MPA) concentration measurements in plasma ultrafiltrate that will be reliable and simple in preparation with deuterated MPA (MPA-d3) chosen as an internal standard. METHODS: The chromatographic separation was made with Zorbax Eclipse XDB-C18 column (4.6x150 mm) using a gradient of two solutions as a mobile phase: A) water and B) methanol, each containing 0...
March 20, 2017: Biomedical Chromatography: BMC
https://www.readbyqxmd.com/read/28315234/ammonium-bicarbonate-addition-improves-the-detection-of-proteins-by-desorption-electrospray-ionization-mass-spectrometry
#7
Elahe Honarvar, Andre R Venter
The analysis of protein by desorption electrospray ionization mass spectrometry (DESI-MS) is considered impractical due to a mass-dependent loss in sensitivity with increase in protein molecular weights. With the addition of ammonium bicarbonate to the DESI-MS analysis the sensitivity towards proteins by DESI was improved. The signal to noise ratio (S/N) improvement for a variety of proteins increased between 2- to 3-fold relative to solvent systems containing formic acid and more than seven times relative to aqueous methanol spray solvents...
March 17, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28314475/pharmacokinetic-based-study-on-lagged-stimulation-of-curcumae-longae-rhizoma-piper-nigrum-couplet-in-their-main-active-components-metabolism-using-uplc-ms-ms
#8
Zhao Chen, Dongmei Sun, Xiaoli Bi, Xiaohui Zeng, Wenhui Luo, Dake Cai, Qiaohuang Zeng, Aili Xu
BACKGROUND: Curcumae Longae Rhizoma is one of the commonly used traditional Chinese medicines, which has multiple biological activities such as relieving stagnation and stasis, pain alleviation, curing amenorrhea and wounds. However, its main active component-curcumin has poor absorption and very fast metabolism in body. To solve this problem, Piper nigrum was introduced for its ability to strengthen bioavailability of other compounds. PURPOSE: In most cases of TCM couplets, all ingredients were prepared and taken simultaneously, which in our opinion did not take full advantage of their interactions...
April 15, 2017: Phytomedicine: International Journal of Phytotherapy and Phytopharmacology
https://www.readbyqxmd.com/read/28306247/reversible-hydrogenation-of-carbon-dioxide-to-formic-acid-and-methanol-lewis-acid-enhancement-of-base-metal-catalysts
#9
Wesley H Bernskoetter, Nilay Hazari
New and sustainable energy vectors are required as a consequence of the environmental issues associated with the continued use of fossil fuels. H2 is a potential clean energy source, but as a result of problems associated with its storage and transport as a gas, chemical H2 storage (CHS), which involves the dehydrogenation of small molecules, is an attractive alternative. In principle, formic acid (FA, 4.4 wt % H2) and methanol (MeOH, 12.6 wt % H2) can be obtained renewably and are excellent prospective liquid CHS materials...
March 17, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28306207/development-and-validation-of-a-uhplc-ms-ms-method-for-the-simultaneous-determination-of-five-bioactive-flavonoids-in-rat-plasma-and-comparative-pharmacokinetic-study-after-oral-administration-of-xiaochaihu-tang-and-three-compatibilities
#10
Yunhai Bo, Lijuan Wang, Xiao Wu, Longshan Zhao, Jingyu Yang, Zhili Xiong, Chunfu Wu
An accurate, rapid and reliable ultra high performance liquid chromatography with tandem mass spectrometry method was developed and validated for the simultaneous determination of baicalin, wogonoside, baicalein, wogonin and oroxylinA in rat plasma. Then, the stability of baicalin and baicalein in the preparation of plasma sample was systematically investigated. The Waters BEH C18 column was used with a gradient mobile phase system of acetonitrile and water containing 0.1% formic acid. The analytes were detected in the multiple reaction monitoring mode with positive electrospray ionization...
March 17, 2017: Journal of Separation Science
https://www.readbyqxmd.com/read/28304035/nuclear-dynamics-and-phase-polymorphism-in-solid-formic-acid
#11
Maciej Krzystyniak, Kacper Drużbicki, Giovanni Romanelli, Matthias J Gutmann, Svemir Rudić, Silvia Imberti, Felix Fernandez-Alonso
We apply a unique sequence of structural and dynamical neutron-scattering techniques, augmented with density-functional electronic-structure calculations, to establish the degree of polymorphism in an archetypal hydrogen-bonded system - crystalline formic acid. Using this combination of experimental and theoretical techniques, the hypothesis by Zelsmann on the coexistence of the β1 and β2 phases above 220 K is tested. Contrary to the postulated scenario of proton-transfer-driven phase coexistence, the emerging picture is one of a quantitatively different structural change over this temperature range, whereby the loosening of crystal packing promotes temperature-induced shearing of the hydrogen-bonded chains...
March 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28303780/purity-evaluation-of-curcuminoids-in-the-turmeric-extract-obtained-by-accelerated-solvent-extraction
#12
Dinesh K Yadav, Khushbu Sharma, Anirban Dutta, Aditi Kundu, Akanksha Awasthi, Arnab Goon, Kaushik Banerjee, Supradip Saha
Curcuminoids, the active principle of <i>Curcuma longa </i>L, is one of the most researched subjects worldwide for its broad-spectrum biological activities. Being traditionally known for their anticancer properties and issues related to bioavailability, the curcuminoids, including diferuloylmethane (curcumin), have gained special attention. Thus, the current study focused on the purity profiling of curcuminoids when extracted by accelerated solvent extraction, which was run with turmeric rhizome powder (20 g) at 1500 psi and at 50°C, with a static time of 10 min and with three cycles...
March 16, 2017: Journal of AOAC International
https://www.readbyqxmd.com/read/28303650/enzymatic-electrosynthesis-of-formic-acid-through-co2-reduction-in-bioelectrochemical-system-bes-effect-of-immobilization-and-carbonic-anhydrase-addition
#13
Sandipam Srikanth, Yolanda Alvarez Gallego, Karolien Vanbroekhoven, Deepak Pant
Enzymatic electrosynthesis of formic acid from carbon dioxide (CO2) reduction using formate dehydrogenase (FDH) as catalyst at cathode both in its free and immobilized forms was studied in detail in bioelectrochemical system (BES). The essential role of solubilizing CO2 for its conversion was also studied by adding carbonic anhydrase (CA) to the FDH enzyme both in free and immobilized forms. FDH alone in the free form showed large variation in reduction current (-6.2±3.9 A/m2), while the immobilized form showed less variation (-3...
March 17, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28303226/simultaneous-determination-of-14-active-constituents-of-shengjiang-xiexin-decoction-using-ultrafast-liquid-chromatography-coupled-with-electrospray-ionization-tandem-mass-spectrometry
#14
Gang Peng, Huanyu Guan, Xiaoming Wang, Yue Shi
An effective herbal medicinal prescription of Shengjiang Xiexin decoction (SXD) was used in treating the inflammatory bowel disease in clinic. In this study, an ultrafast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) method was developed to separate and to simultaneously determine 14 major active ingredients in SXD. Chromatographic separation was successfully accomplished on an Acquity BEH C18 (100 mm×2.1 mm, 1.7 μm) column using gradient elution with 0.1% (v/v) formic acid water (A) and 0...
March 2017: Acta Pharmaceutica Sinica. B
https://www.readbyqxmd.com/read/28300024/development-and-validation-of-a-rapid-lc-ms-ms-method-for-simultaneous-determination-of-kaempferol-and-quercetin-in-thespesia-populnea-extract
#15
Hiteksha Panchal, Mamta B Shah
In this study, a simple and rapid LC with tandem MS method was developed and validated for the simultaneous determination of kaempferol and quercetin in <i>Thespesia populnea</i> extract. The compounds were eluted using a Gemini C18 column (50 × 2.0 mm, 3 μm), with the mobile phase consisting of acetonitrile–0.3% formic acid in water at the flow rate of 0.400 mL/min. The assay exhibited a linear dynamic range of 25–2500 ng/mL for both kaempferol and quercetin. The values for intra- and interday precision and accuracy were well within the generally accepted criteria for analytical methods (<15%)...
March 16, 2017: Journal of AOAC International
https://www.readbyqxmd.com/read/28300023/optimization-and-validation-of-a-residue-analysis-method-for-glyphosate-glufosinate-and-their-metabolites-in-plant-matrixes-by-liquid-chromatography-with-tandem-mass-spectrometry
#16
Dasharath P Oulkar, Sandip Hingmire, Arnab Goon, Manjusha Jadhav, Bharat Ugare, Ahammed Shabeer Thekkumpurath, Kaushik Banerjee
A sensitive and accurate LC with tandem MS (MS/MS)-based method was developed and validated for the analysis of the herbicide glyphosate, its metabolite aminomethylphosphonic acid (AMPA), and glufosinate after derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl) in various plant matrixes. The method also covers direct analysis of the glufosinate metabolites 3-methylphosphinicopropionic acid (3-MPPA) and N-acetyl-glufosinate (NAG). The homogenized samples were extracted with 0.1% formic acid in water-dichloromethane (50 + 50)...
March 23, 2017: Journal of AOAC International
https://www.readbyqxmd.com/read/28299804/simultaneous-determination-of-piperaquine-and-its-n-oxidated-metabolite-in-rat-plasma-using-lc-ms-ms
#17
Huixiang Liu, Meitong Zang, Aijuan Yang, Jianbo Ji, Jie Xing
A sensitive and efficient liquid chromatography tandem mass spectrometry method was firstly developed and validated for the simultaneous determination of piperaquine (PQ) and its N-oxidated metabolite (PQ-M) in plasma. A simple protein precipitation procedure was used for sample preparation. Adequate chromatographic retention was achieved on a C18 column under gradient elution with acetonitrile and 2 mM aqueous ammonium acetate containing 0.15% formic acid and 0.05% trifluoroacetic acid. A triple-quadrupole mass spectrometer equipped with an electrospray source was set up in the positive ion mode and multiple reaction monitoring mode...
March 16, 2017: Biomedical Chromatography: BMC
https://www.readbyqxmd.com/read/28294360/development-of-a-lc-ms-ms-method-for-quantification-of-two-pairs-of-isomeric-flavonoid-glycosides-and-other-ones-in-rat-plasma-application-to-pharmacokinetic-studies
#18
Sixi Zhang, Yang Xie, Jing Wang, Yanmei Geng, Yu Zhou, Chengxin Sun, Guangshu Wang
An liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for simultaneous determination of six flavonoid glycosides including isoorientin (1), orientin (2), 2″-O-β-D-xylopyranosyl isoorientin (3), 2″-O-β-D-xylopyranosyl isovitexin (4), 6-C-L-α-arabipyranosyl vitexin (5), and vitexin (6) in rat plasma using isoquercitrin as the internal standard (IS). Plasma samples were prepared by a one-step protein precipitation with acetonitrile. Chromatographic analysis was carried out on a 25-cm C18 column with a gradient mobile phase consisting of acetonitrile and 0...
March 10, 2017: Biomedical Chromatography: BMC
https://www.readbyqxmd.com/read/28294235/steam-reforming-of-methanol-over-oxide-decorated-nanoporous-gold-catalysts-a-combined-in-situ-ftir-and-flow-reactor-study
#19
J Shi, C Mahr, M M Murshed, T M Gesing, A Rosenauer, M Bäumer, A Wittstock
Methanol as a green and renewable resource can be used to generate hydrogen by reforming, i.e., its catalytic oxidation with water. In combination with a fuel cell this hydrogen can be converted into electrical energy, a favorable concept, in particular for mobile applications. Its realization requires the development of novel types of structured catalysts, applicable in small scale reactor designs. Here, three different types of such catalysts were investigated for the steam reforming of methanol (SRM). Oxides such as TiO2 and CeO2 and mixtures thereof (Ce1Ti2Ox) were deposited inside a bulk nanoporous gold (npAu) material using wet chemical impregnation procedures...
March 15, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28294219/the-role-of-electron-interfacial-transfer-in-mesoporous-nano-tio2-photocatalysis-a-combined-study-of-in-situ-photoconductivity-and-numerical-kinetic-simulation
#20
Baoshun Liu, Jingjing Yang, Xiujian Zhao, Jiaguo Yu
In this research, a combination of in situ photoconductivity (σ) and kinetic simulations was used to study the role of electron interfacial transfer (IT) in the gaseous photocatalysis of formic acid by mesoporous nanocrystalline TiO2. The effects of light intensity, initial formic acid concentrations, oxygen amounts, and temperature on the in situ σ and the photocatalytic courses were studied in detail. The temperature dependence of in situ σ clearly shows that the electron transfer is determined by the IT of electrons to O2 rather than by the transport...
March 15, 2017: Physical Chemistry Chemical Physics: PCCP
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