Search results for "ethanol"
showing 10 items of 2041 documents
Determination of muscimol and ibotenic acid in mushrooms of Amanitaceae by capillary electrophoresis
2014
In this study, the CZE method for rapid quantitative and qualitative determination of ibotenic acid and muscimol in Amanita mushrooms naturally grown in Poland was developed. The investigations included the species of A. muscaria, A. pantherina, and A. citrina, collected in southern region of Poland. The studied hallucinogenic compounds were effectively extracted with a mixture of methanol and 1 mM sodium phosphate buffer at pH 3 (1:1 v/v) using ultrasound-assisted procedure. The obtained extracts were separated and determined by CZE utilizing a 25 mM sodium phosphate running buffer adjusted to pH 3 with 5% content of acetonitrile v/v. The calibration curves for both analytes were linear in…
ChemInform Abstract: Fluoro Heterocycles. A Photochemical Methodology for the Synthesis of 3-Amino- and 3-(N-Alkylamino)-5-perfluoroalkyl-1,2,4-oxadi…
2000
Abstract A photochemical methodology for the synthesis of perfluoroalkyl-1,2,4-oxadiazoles has been described. 3-Amino- and 3-( N -alkylamino)-5-perfluoroalkyl-1,2,4-oxadiazoles have been prepared by irradiation of 3-perfluoroalkanoylamino-4-phenyl-1,2,5-oxadiazoles (furazans) at λ =313 nm in methanol and in the presence of ammonia or primary aliphatic amines.
Requirement for the Proton-Pumping NADH Dehydrogenase I of Escherichia Coli in Respiration of NADH to Fumarate and Its Bioenergetic Implications
1997
In Escherichia coli the expression of the nuo genes encoding the proton pumping NADH dehydrogenase I is stimulated by the presence of fumarate during anaerobic respiration. The regulatory sites required for the induction by fumarate, nitrate and O2 are located at positions around –309, –277, and downstream of –231 bp, respectively, relative to the transcriptional-start site. The fumarate regulator has to be different from the O2 and nitrate regulators ArcA and NarL. For growth by fumarate respiration, the presence of NADH dehydrogenase I was essential, in contrast to aerobic or nitrate respiration which used preferentially NADH dehydrogenase II. The electron transport from NADH to fumarate …
Direct gravimetric sensing of GBL by a molecular recognition process in organic cage compounds.
2013
Organic cages were identified as highly potent affinity materials for the tracing of γ-butyrolactone. The selectivity over ethanol and water is based on the interior functional groups which allow preferential hydrogen bonding to the target analyte.
Sub- and supercritical fluid extraction of trichloropyridinol from soil prior to immunoassay
1997
A comparative study on the extraction of TCP (3,5,6-trichloro-2-pyridinol, a metabolite of chlorpyrifos) from soil with CO2 and H2O is reported. The polarity of the analyte requires the presence of both a cosolvent (methanol) and an ion-pair reagent [(1R)-(-)-10-camphorsulfonic acid ammonium salt] for 95% extraction in 30 min when supercritical CO2 at 40 degrees C and 383 bar is used as extractant. Subcritical water (250 degrees C and 200 bar) enables complete extraction within 15 min without additives. Quantitation of the target analyte is performed by specific immunoassay using a non-commercial monoclonal antibody which provides a linear determination range between 0.005 and 5 micrograms/…
Towards a microbial thermoelectric cell.
2013
Microbial growth is an exothermic process. Biotechnological industries produce large amounts of heat, usually considered an undesirable by-product. In this work, we report the construction and characterization of the first microbial thermoelectric cell (MTC), in which the metabolic heat produced by a thermally insulated microbial culture is partially converted into electricity through a thermoelectric device optimized for low ΔT values. A temperature of 41°C and net electric voltage of around 250–600 mV was achieved with 1.7 L baker’s yeast culture. This is the first time microbial metabolic energy has been converted into electricity with an ad hoc thermoelectric device. These results might…
Reactions of platinum(iv)-bound nitriles with isomeric nitroanilines: addition vs. substitution
2012
The platinum(IV) complex trans-[PtCl(4)(EtCN)(2)] reacts smoothly and under mild conditions with isomeric o-, m- and p-nitroanilines (NAs) yielding two different types of products depending on the NA isomer, viz. the nitroaniline complexes cis/trans-[PtCl(4)(NA)(2)] (cis/trans-1-3) and the amidine species trans-[PtCl(4){NH=C(Et)NHC(6)H(4)NO(2)-m}(EtCN)] (4), trans-[PtCl(4){NH=C(Et)NHC(6)H(4)NO(2)-m}(2)] (5) and trans-[PtCl(4){NH=C(Et)NHC(6)H(4)NO(2)-p}(EtCN)] (6). Complexes 4 and 5 undergo cyclometalation, furnishing mer-[PtCl(3){NH=C(Et)NHC(6)H(3)NO(2)-m}(EtCN)] (7) and mer-[PtCl(3){NH=C(Et)NHC(6)H(4)NO(2)-m}{NH=C(Et)NHC(6)H(3)NO(2)-m}] (8), respectively. Moreover, 8 both in the solid stat…
Development and validation of a liquid chromatography tandem mass spectrometry method for the analysis of beta-agonists in animal feed and drinking w…
2010
A reproducible, sensitive and selective multiresidue analytical method for seven beta-agonists: clenbuterol (CBT), clenpenterol (CPT), ractopamine (RTP), brombuterol (BBT), mabuterol (MBT), mapenterol (MPT), and hydroxymethylclenbuterol (HMCBT) was developed and validated by using liquid chromatography tandem mass spectrometry (LC-MS/MS) in feed and drinking water samples. The validation was achieved according to the criteria laid down in the Commission Decision 2002/657/EC, however it was necessary to use minimum required performance limits (MRPLs) proposed by the Community Reference Laboratories (CRLs) due to the lack of maximum residue limits (MRLs) for beta-agonists. By setting up these…
Determination of fatty alcohol ethoxylates and alkylether sulfates by anionic exchange separation, derivatization with a cyclic anhydride and liquid …
2011
A method for the separation, characterization and determination of fatty alcohol ethoxylates (FAE) and alkylether sulfates (AES) in industrial and environmental samples is described. Separation of the two surfactant classes was achieved in a 50:50 methanol-water medium by retaining AES on a strong anionic exchanger (SAX) whereas most FAE were eluted. After washing the SAX cartridges to remove cations, the residual hydrophobic FAE were eluted by increasing methanol to 80%. Finally, AES were eluted using 80:20 and 95:5 methanol-concentrated aqueous HCl mixtures. Methanol and water were removed from the FAE and AES fractions, and the residues were dissolved in 1,4-dioxane. In this medium, este…
Determination of non-ionic and anionic surfactants in industrial products by separation on a weak ion-exchanger, derivatization and liquid chromatogr…
2013
Abstract A method for the determination of priority surfactants, including fatty alcohol ethoxylates (FAE), alkylether sulfates (AES) and linear alkylbenzene sulfonates (LAS) is described. The samples were diluted with 50% methanol at pH 4 prior to solid-phase extraction on a weak anionic exchanger (WAX). The AES and LAS surfactant classes were retained, whereas the non-ionic components, including most FAE oligomers were eluted. After washing the WAX cartridge to remove cations, the remaining hydrophobic FAE oligomers were eluted using hot 80% methanol at pH 4 (at ca. 50 °C). These two eluates were combined to constitute the non-ionic fraction. Then, AES and LAS were eluted using 80% MeOH w…