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21.
Simultaneous Determination of Caffeine,Ibuprofen, and Paracetamol by Flow‐injection Analysis with Multiple‐pulse Amperometric Detection on Boron‐doped Diamond Electrode
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Sandro C. Chaves Priscila N. C. Aguiar Lívia M. F. C. Torres Eric S. Gil Rita C. S. Luz Flávio S. Damos Rodrigo A. A. Munoz Eduardo M. Richter Wallans T. P. dos Santos 《Electroanalysis》2015,27(12):2785-2791
This work presents a simple, fast and low‐cost method for the simultaneous determination of three drugs by flow‐injection analysis with multiple‐pulse amperometric (MPA) detection using a wall‐jet flow cell with a boron‐doped diamond electrode. The amperometric determination of caffeine (CF), ibuprofen (IB) and paracetamol (PC) was performed by the application of a four‐potential waveform using the MPA technique. PC is oxidized at E1 (1.20 V/70 ms) and thus selectively detected; PC and CF are oxidized at E2 (1.49 V/40 ms); PC, CF and IB are oxidized at E3 (1.70 V/70 ms); and E4 (1.80 V/100 ms) is applied for electrode cleaning. The subtraction of currents obtained at the different potentials did not provide accurate determinations of CF and IB, thus it was required to investigate correction factors to determine CF and IB without the interference from PC and CF using the respective amperometric signals obtained at E2 and E3. The proposed method was successfully applied for the determination of three drugs in pharmaceutical samples with low generation of residues and a high analytical frequency (150 h?1) in comparison with HPLC‐DAD method. 相似文献
22.
Carolina M.F. Calixto Priscila Cervini 《International journal of environmental analytical chemistry》2013,93(5):561-570
A bare graphite-epoxy composite was evaluated as an electrode material in the determination of atenolol in natural water samples and pharmaceutical formulations for which the analyte was spiked. Using a DPV procedure, a linear response was observed in the 4.45–84.7?µmol?L?1 range with a LOD?=?2.23?µmol?L?1, without need of surface renewal between successive runs, and recoveries between 92.5 and 107.5% for pharmaceutical formulations. The results obtained from the proposed procedure agreed with HPLC results within a 95% confidence level. During the determination of atenolol in water samples, recoveries between 96.1 and 102.6% were found. 相似文献
23.
Trentin Priscila O. Perardt Mariana Medeiros-Junior Ronaldo A. 《Journal of Thermal Analysis and Calorimetry》2022,147(12):6631-6642
Journal of Thermal Analysis and Calorimetry - The search for new materials to replace Portland cement (PC) has increased due to the high release of carbon dioxide (CO2) and the exploration of raw... 相似文献
24.
Ana P. Fernandes Priscila F.B. SousaValerio L. Borges Gilmar Guimaraes 《Applied Mathematical Modelling》2010
Inverse problems can be found in many areas of science and engineering and can be applied in different ways. Two examples can be cited: thermal properties estimation or heat flux function estimation in some engineering thermal process. Different techniques for the solution of inverse heat conduction problem (IHCP) can be found in literature. However, any inverse or optimization technique has a basic and common characteristic: the need to solve the direct problem solution several times. This characteristic is the cause of the great computational time consumed. In heat conduction problem, the time consumed is, usually, due to the use of numerical solutions of multidimensional models with refined mesh. In this case, if analytical solutions are available the computational time can be reduced drastically. This study presents the development and application of a 3D-transient analytical solution based on Green’s function. The inverse problem is due to the thermal properties estimation of conductors. The method is based on experimental determination of thermal conductivity and diffusivity using partially heated surface method without heat flux transducer. Originally developed to use numerical solution, this technique can, using analytical solution, estimate thermal properties faster and with better accuracy. 相似文献
25.
C. H. Collins C. A. Bertran A. L. Pires Valente Priscila de A. Leone A. L. M. Murta K. E. Collins 《Chromatographia》1988,26(1):168-170
Summary Separation of perhalogenated compounds resulting from thermolysis, photolysis or radiolysis of mixtures of halogens in carbon tetrachloride was carried out by programmed temperature gas chromatography. Plots of relative retentions (to CBr4) vs the number of bromine atoms present for known compounds of the general formula CxBryClz (x=1 and 2; y+z=4 or 6) gave three linear correlations (all with r>0.99). These correlations permitted projections of the identities of reaction products for which no standards were available. These projections were later confirmed by CG-MS. *** DIRECT SUPPORT *** A0732166 00010 相似文献
26.
Agerdnio Andrade de Souza Brenda Lorena Snchez Ortíz Rosemary de Carvalho Rocha Koga Priscila Faimann Sales Divino Bruno da Cunha Ana Luiza Mantovaneli Guerra Gisele Custdio de Souza Jos Carlos Tavares Carvalho 《Molecules (Basel, Switzerland)》2021,26(24)
Plant-derived products may represent promising strategies in the treatment of Neglected Tropical Diseases (NTDs). From this perspective, it is observed that the Amazon phytogeographic region contains the tribe Canarieae of the Burseraceae family, composed of trees and shrubs supplied with resin channels. Its uses in folk medicine are related to aromatic properties, which have numerous medicinal applications and are present in reports from traditional peoples, sometimes as the only therapeutic resource. Despite its economic and pharmacological importance in the region, and although the family is distributed in all tropical and subtropical regions of the world, most of the scientific information available is limited to Asian and African species. Therefore, the present work aimed to review the secondary metabolites with possible pharmacological potential of the species Trattinnickia rhoifolia Willd, popularly known as “Breu sucuruba”. To this end, an identification key was created for chemical compounds with greater occurrence in the literature of the genus Trattinnickia. The most evident therapeutic activities in the consulted studies were antimicrobial, antioxidant, anti-inflammatory, antiviral, antifungal, anesthetic and antiparasitic. An expressive chemical and pharmacological relevance of the species was identified, although its potential is insufficiently explored, mainly in the face of the NTDs present in the Brazilian Amazon. 相似文献
27.
Raffaella Cincinelli Sabrina Dallavalle Lucio Merlini Raffaella Nannei Leonardo Scaglioni 《Tetrahedron》2009,65(17):3465-5823
Acid treatment of indole-2-carboxylic acid β- and γ-oxoamides causes Friedel-Crafts intramolecular cyclization to β-carbolinones and dihydro-2H-azepino[3,4-b]indol-1-ones, in contrast to secondary δ-,?-, and ζ-oxoamides, which cyclize to the novel heterocyclic rings pyrrolizino[2,1-b]indole, indolizino[2,1-b]indole, and 9a,11-diaza-indeno[1,2-a]azulene, via an intermediate N-acyliminium ion. Tertiary amides lead only the Friedel-Crafts ring closure, thus allowing the synthesis of larger fused rings. 相似文献
28.
Priscila O. Cinto Ana Luiza Ribeiro Souza Andréa C. Lima Marco V. Chaud Maria Palmira D. Gremi?o 《Chromatographia》2009,69(Z2):213-217
Praziquantel (PZQ) is a highly lipophilic drug with low aqueous solubility. Despite this, it is well absorbed from the gastrointestinal
tract. In this study, a simple LC method was developed and validated, in order to monitor the concentration of PZQ in TC-199
buffer in vitro, in the rat everted gut sac absorption model. PZQ was analyzed by a reversed-phase LC method with an isocratic
mobile phase containing acetonitrile and water in the proportions 45:55. The flow-rate was 1 mL min−1 and PZQ was determined by measuring absorbance at 215 nm, at 25 °C. The method was found to be specific, as none of the components
of TC-199 or intestinal sac artefacts interfered with the drug peak. Recovery was within acceptable statistical limits. The
limit of detection was 0.54 μg mL−1 and the limit of quantitation was 1.63 μg mL−1. The calibration curve was found to be linear in the concentration range of 10–90 μg mL−1 PZQ. The proposed method was found to be rapid and selective and hence can be applied in the monitoring of the absorption
of PZQ in in vitro everted gut sac absorption studies. 相似文献
29.
Paul J. Robinson Julen Munarriz Michael E. Valentine Austin Granmoe Natalia Drichko Juan R. Chamorro Priscila F. Rosa Tyrel M. McQueen Anastassia N. Alexandrova 《Angewandte Chemie (International ed. in English)》2020,59(27):10996-11002
Samarium hexaboride is an anomaly, having many exotic and seemingly mutually incompatible properties. It was proposed to be a mixed‐valent semiconductor, and later a topological Kondo insulator, and yet has a Fermi surface despite being an insulator. We propose a new and unified understanding of SmB6 centered on the hitherto unrecognized dynamical bonding effect: the coexistence of two Sm?B bonding modes within SmB6, corresponding to different oxidation states of the Sm. The mixed valency arises in SmB6 from thermal population of these distinct minima enabled by motion of B. Our model simultaneously explains the thermal valence fluctuations, appearance of magnetic Fermi surface, excess entropy at low temperatures, pressure‐induced phase transitions, and related features in Raman spectra and their unexpected dependence on temperature and boron isotope. 相似文献
30.
Recent generalizations of the Camassa–Holm equation are studied from the point of view of existence of global solutions, criteria for wave breaking phenomena and integrability. We provide conditions, based on lower bounds for the first spatial derivative of local solutions, for global well-posedness in Sobolev spaces for the family under consideration. Moreover, we prove that wave breaking phenomena occurs under certain mild hypothesis. Based on the machinery developed by Dubrovin [Commun. Math. Phys. 267, 117–139 (2006)] regarding bi-Hamiltonian deformations, we introduce the notion of quasi-integrability and prove that there exists a unique bi-Hamiltonian structure for the equation only when it is reduced to the Dullin–Gotwald–Holm equation. Our results suggest that a recent shallow water model incorporating Coriollis effects is integrable only in specific situations. Finally, to finish the scheme of geometric integrability of the family of equations initiated in a previous work, we prove that the Dullin–Gotwald–Holm equation describes pseudo-spherical surfaces. 相似文献