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101.
César IC Byrro RM de Santana E Silva Cardoso FF Mundim IM de Souza Teixeira L Rezende KR da Silva EP Gomes SA de Sousa VA Bonfim RR Pianetti GA 《Biomedical chromatography : BMC》2012,26(7):851-856
A rapid method for the quantification of glucosamine in human plasma using high‐performance liquid chromatography coupled to tandem mass spectrometry was developed and validated. The sample preparation includes a simple deproteinization step, using d ‐[1‐13C] glucosamine hydrochloride as an internal standard. Chromatographic separation was performed on an ACE Ciano column using isocratic elution with acetonitrile and aqueous 2 mm ammonium acetate containing 0.025% formic acid (80:20). Selected reaction monitoring was performed using the transitions m/z 180.1 → m/z 72.1 and m/z 181.0 → m/z 74.6 to quantify glucosamine and internal standard, respectively. The method was validated and proved to be linear, accurate and precise over the range 50–5000 ng/mL of glucosamine. Recovery rates higher than 90% were obtained for both glucosamine and internal standard. No matrix effect was detected in the samples. The validated method was successfully applied to a pharmacokinetic study after oral administration of a powder for oral solution formulation containing glucosamine sulfate. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
102.
Nívia Maria Melo Coelho Edmar Isaías de Melo Hélen Cristine de Rezende Ana Graci Brito-Madurro João Marcos Madurro 《Journal of Solid State Electrochemistry》2012,16(3):945-951
In this work, carbon electrodes modified with aminophenols were developed for the production of pesticides biosensors based on acetylcholinesterase. The polymers were potentiodynamically deposited on a graphite electrode surface by the oxidation of monomers, 2-aminophenol, 3-aminophenol and 4-aminophenol. The electrochemical behaviour and surface analysis of the electrodes modified by polyaminophenols non-immobilized and immobilized on acetylcholinesterase were studied by cyclic voltammetry, electrochemical impedance spectroscopy and atomic force microscopy. Roughness values obtained for graphite electrodes modified with poly(4-aminophenol) and poly(4-aminophenol)/acetylcholinesterase were 174 and 86 nm, respectively. The acetylcholinesterase enzyme was immobilized on a graphite and a graphite modified with poly(4-aminophenol), and these electrodes were coupled in the flow system. Potentiometric response due to hydrogen ions generated by an enzymatic system in the presence of acetylcholine chloride substrate was evaluated. The results showed that the graphite/poly(4-aminhophenol) sensor presents high sensitivity to hydrogen ions when compared with other graphite/polyaminophenols sensors. The biosensor coupled in a continuous flow system was employed for the detection of dichlorvos. The detection and quantification limits were 0.8 and 2.4 μmol L−1 dichlorvos, respectively. This sensor reveals an efficient and promising material for biomolecules immobilization. 相似文献
103.
Paula Teixeira Helena Lopes Ibrahim Gulyurtlu Nuno Lapa 《Accreditation and quality assurance》2012,17(2):159-166
Mass balances of ash and potassium for a fluidized bed combustor were performed incorporating measurement uncertainties. The
total output mass of ash or a chemical element should be equal to the mass in the input fuel; however, this is not often achieved.
A realistic estimation of recovery uncertainty can support the reliability of a mass balance. Estimation of uncertainty helps
to establish a reliable evaluation of the recovery ratio of ash mass and elemental mass. This may clarify whether any apparent
lack in closing the mass balance can be attributed to uncertainties. The evaluation of measurement uncertainty for different
matrices, namely coal, biomass, sand and ashes from different streams was based on internal quality control data and external
quality control data, namely analysis of samples from proficiency tests or use of a certified reference material. The evaluation
of intermediate precision and trueness allowed the estimation of measurement uncertainty. Due to the different physic and
chemical characteristics of the studied matrices, the uncertainty of precision was evaluated using R-charts of data obtained
from the analysis of duplicates for the majority of samples. This allowed evaluating sample heterogeneity effects. The instrumental
acceptance criterion was also considered and included in the combined uncertainty. The trueness was evaluated using data from
several proficiency tests and from analysis of a certified reference material or sample spiking. Statistically significant
bias was included. 相似文献
104.
Schwab NV Porcari AM Coelho MB Schmidt EM Jara JL Visentainer JV Eberlin MN 《The Analyst》2012,137(11):2537-2540
An exceptionally easy to assemble source for ambient mass spectrometry is described. Based on Venturi easy ambient sonic-spray ionization (V-EASI), the source was further simplified by the use of a can of compressed air which simultaneously provides solution or solvent Venturi self-pumping and continuous, stable and abundant low-noise ion signal via voltage-free sonic-spraying. Further simplification was also attained by the use of inexpensive and readily commercially available parts: a surgical 2-way catheter, an aerosol can of compressed air, a 30 cm long fused-silica capillary and a hypodermic needle. This "Spartan" V-EASI source seems to offer one of the easiest and cheapest ways to make ions for ambient desorption/ionization mass spectrometry analysis of both liquid and solid samples. 相似文献
105.
JL García Ruano L Marzo V Marcos C Alvarado J Alemán 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(32):9775-9779
Center of attention: A new approach for the synthesis of enantiomerically enriched allenes by isomerization of 2-p-tolylsulfinylphenyl propargylic derivatives is presented, which in turn are prepared by reaction of sulfinylated lithium benzylcarbanions with arylsulfonylacetylenes. The high control of stereoselectivity in both steps is exerted by the sulfinyl group. 相似文献
106.
107.
Mandado M Mosquera RA Van Alsenoy C 《Physical chemistry chemical physics : PCCP》2005,7(18):3290-3296
The presence of intramolecular hydrogen bond (IHB) in beta-hydroxyethylperoxy and beta-hydroxyethoxy radicals was investigated using the QTAIM topological study on UB3LYP/6-311++G(2d,2p) charge densities. Only one of the two conformers of beta-hydroxyethylperoxy radical which were previously considered to present IHB displays a bond critical point (BCP) associated to an IHB. Furthermore, the atomic energies and electron populations indicate no evidence of IHB in the second conformer. Nevertheless, very small differences in molecular energies were obtained using several one-step and multi-step methods (G3, G3B3) between both conformers. No BCP is found between the hydroxyl hydrogen and the oxygen in the most stable conformer or in the transition state for the dissociation path of beta-hydroxyethoxy radical. However, a BCP is formed in the last steps of this path, thereby yielding H-bonded products. 相似文献
108.
Arlindo Csar Matias Pereira Helison de Oliveira Carvalho Danna Emanuelle Santos Gonalves Karyny Roberta Tavares Picano Abraho Victor Tavares de Lima Teixeira dos Santos Heitor Ribeiro da Silva Francinaldo Sarges Braga Roberto Messias Bezerra Alessandro de Sousa Nunes Maira Tiyomi Sacata Tongo Nazima Júlia Gomes Cerqueira Talisson Taglialegna Janayra Maris Teixeira Jos Carlos Tavares Carvalho 《Molecules (Basel, Switzerland)》2021,26(16)
This study aimed to evaluate and compare the effects of co-treatment with purified annatto oil (PAO) or its granules (GRA, Chronic®) with that of testosterone on the orchiectomy-induced osteoporosis in Wistar rats. After surgery, rats were treated from day 7 until day 45 with testosterone only (TES, 7 mg/kg, IM) or TES + PAO or GRA (200 mg/kg, p.o.). The following parameters were evaluated: food/water intake, weight, HDL, LDL, glucose, triglycerides (TG), total cholesterol (TC), alkaline phosphatase levels, blood phosphorus and calcium contents, femur weight, structure (through scanning electron microscopy), and calcium content (through atomic absorption spectrophotometry). Our results show that orchiectomy could significantly change the blood lipid profile and decrease bone integrity parameters. Testosterone reposition alone could improve some endpoints, including LDL, TC, bone weight, and bone calcium concentration. However, other parameters were not significantly improved. Co-treatment with PAO or GRA improved the blood lipid profile and bone integrity more significantly and improved some endpoints not affected by testosterone reposition alone (such as TG levels and trabeculae sizes). The results suggest that co-treatment with annatto products improved the blood lipid profile and the anti-osteoporosis effects of testosterone. Overall, GRA had better results than PAO. 相似文献
109.
Alexsandro J. dos Santos Matheus S. Kronka Guilherme V. Fortunato Marcos R.V. Lanza 《Current Opinion in Electrochemistry》2021
This short review presents a critical overview of the most recent works published in the literature related to the use of electrochemical advanced oxidation processes (EAOPs) for the treatment of antibiotics present in synthetic and real wastewaters. The first section focuses on novelties within the traditional EAOPs, including electrochemical oxidation and electrochemical Fenton-based processes. The second section is devoted to new electrochemical technologies, including heterogeneous electro-Fenton, electrochemically activated persulfate processes, and combined processes. Future perspectives about these processes are also presented to aid the continuous evolution of research in the area. 相似文献
110.
Effect of viscosity of a liquid membrane containing oleyl alcohol on the pertraction of butyric acid
Marek Blahušiak Ján Marták Fernando Miranda Štefan Schlosser José A. Teixeira 《Chemical Papers》2013,67(12):1560-1568
Solvent formulation is important in the optimization of the mass-transfer through supported liquid membranes (SLM) in pertraction and membrane extraction. Oleyl alcohol (OA) is frequently used as the solvent or diluent in the extraction of carboxylic acids. A disadvantage of OA is its relatively high viscosity of 28.32 mPa s at 25°C. This can be decreased by the application of a less viscous OA diluent, e.g. dodecane. The relationship between the ratio of the distribution coefficient of butyric acid (BA), D F, and the viscosity of OA-dodecane solvents, µ, as extraction and transport characteristics, and the overall mass-transfer coefficient, K p, through SLMs was analyzed. Dependence of the D F/µ ratio on the OA concentration showed a maximum at the OA concentration of 15 mass % to 30 mass %. The OA concentration dependence of K p for SLMs exhibited also a maximum at about 30 mass % and 20 mass % of OA at the BA concentration driving force of 0.12 kmol m?3 and 0.3 kmol m?3, respectively. Shifting of the maximum in K p dependences towards lower OA concentrations by increasing the BA concentration driving force is in agreement with the D F/µ ratio dependence. Using pure OA as the solvent or diluent is not preferable and a mixture of a low viscosity diluent with the OA concentration below 40 mass % should be used. The presented results show the potential of the D F/µ ratio in the screening and formulation of solvents in extraction and SLM optimization. 相似文献