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排序方式: 共有132条查询结果,搜索用时 15 毫秒
51.
Balest R Cho K Ford WT Johnson DR Lingel K Lohner M Rankin P Smith JG Alexander JP Bebek C Berkelman K Bloom K Browder TE Cassel DG Cho HA Coffman DM Crowcroft DS Drell PS Dumas DJ Ehrlich R Gaidarev P Garcia-Sciveres M Geiser B Gittelman B Gray SW Hartill DL Heltsley BK Henderson S Jones CD Jones SL Kandaswamy J Katayama N Kim PC Kreinick DL Ludwig GS Masui J Mevissen J Mistry NB Ng CR Nordberg E Patterson JR Peterson D Riley D Salman S Sapper M Würthwein F Avery P Freyberger A Rodriguez J 《Physical review D: Particles and fields》1995,52(5):2661-2672
52.
Capillary electrophoresis (CE) can be used for the rapid determination of pharmaceuticals, particularly in routine quality control analysis. This paper focuses on several approaches aimed at decreasing the analysis time with commercially available instrumentation by (i) application of a high electric field through a reduced capillary, (ii) use of a dynamically coated capillary to increase the electroosmotic flow, (iii) short-end injection (SEI) technique, and (iv) application of multiple sample injections. Moreover, SEIs were combined with the three other approaches. A pharmaceutical formulation containing lidocaine as an active component was selected, and the methods were validated according to the ICH guidelines. The seven approaches investigated fulfilled different statistical requirements and demonstrated their linearity and trueness, with good recoveries and confidence limits always inferior to 1.5%. Furthermore, relative standard deviation (RSD) values for repeatability and intermediate precision were inferior to 1.1 and 1.8%, respectively. These results confirmed that each approach is of utmost interest to increase the analyte throughput in CE. 相似文献
53.
Geiser L Henchoz Y Galland A Carrupt PA Veuthey JL 《Journal of separation science》2005,28(17):2374-2380
CZE allows to measure the acidic dissociation constant (pKa) of many drug substances. However, determining the EOF intensity may be time-consuming, especially at a low pH. In order to overcome this drawback, a dynamic coating procedure of the capillary was carried out to increase microEOF, and thus to reduce the analysis time. In addition, this coating procedure enhanced migration time stability. The effective mobilities of 15 compounds were measured at different pH, producing pK'a values dependent on BGE ionic strength. The latter values were corrected with the activity coefficient to obtain a "true" pKa value. The 15 investigated compounds were (i) five acids: namely, salicylic acid, benzoic acid, ketoprofen, phenobarbital, and phenol, (ii) four bases: lidocaine, propafenone, propranolol, and quinine, (iii), five ampholytes: sulfanilamide, sulfabenzamide, sulfadimethoxine, sulfadoxine, and sulfisoxazole, and (iv) one zwitterion: cetirizine. The range of determined pKa values was between 1.2 and 11.2, and close to the pKa values available from the literature. 相似文献
54.
Curreli S Deplano P Mercuri ML Pilia L Serpe A Schlueter JA Whited MA Geiser U Coronado E Gómez-García CJ Canadell E 《Inorganic chemistry》2004,43(6):2049-2056
We report the synthesis, structure, and physical properties of (BEDT-TTF)[Ni(tdas)2] [BEDT-TTF, or ET, is bis(ethylenedithio)tetrathiafulvalene; tdas is 1,2,5-thiadiazole-3,4-dithiolate], which is the first example of a salt containing monomeric [Ni(tdas)2]- monoanions. This salt, which crystallizes in the monoclinic space group P2(1)/c with a = 17.2324(6) A, b = 13.2740(5) A, c = 10.9467(4) A, beta = 96.974(2) degrees, and V = 2485.5(2) A(3), forms a layered structure. One layer contains dimerized BEDT-TTF electron donor molecules and isolated [Ni(tdas)2]- monoanions, while the second layer contains chains of [Ni(tdas)2]- monoanions. Conductivity measurements show that (BEDT-TTF)[Ni(tdas)2] has a semiconductor-to-semiconductor transition near 200 K, while magnetic measurements indicate that it is an S = 1/2 paramagnet with weak antiferromagnetic coupling. Reflectance spectra reveal bands in the near-infrared region (6.6 x 10(3) and 10.6 x 10(3) cm(-1)) which are typical of (BEDT-TTF)2(2+) dimers. From these data, we can conclude that the unpaired electron lies on the [Ni(tdas)2]- anions. Tight-binding band structure calculations were used to analyze the electronic structure of this salt. 相似文献
55.
Laís P. Silva Fernando C. Vicentini Bruna C. Lourencao Geiser G. Oliveira Marcos R. V. Lanza Orlando Fatibello-Filho 《Journal of Solid State Electrochemistry》2016,20(9):2395-2402
A glassy carbon electrode (GCE) modified with carbon Printex 6L (Printex6L/GCE) as a novel sensor is proposed. A morphological study was carried out using scanning electron microscopy, and an electrochemical characterization of the proposed electrode was performed by cyclic voltammetry (CV) using [Fe(CN)6]4? as a redox probe. With the incorporation of the carbon Printex 6L film onto the GCE surface, the [Fe(CN)6]4? analytical signal was substantially increased and the difference between the oxidation and reduction potentials (ΔE p) decreased, a characteristic of the electrocatalytic effect. Furthermore, the use of carbon Printex 6L film resulted in an 84 % increase in the oxidation current and a 123 % increase in the reduction current. Faster charge transfer was observed at the proposed electrode/electrolyte interface during CV when compared with GCE. The Printex6L/GCE was tested for ranitidine (RNT) sensing and showed a decrease in the working potential and an increase in the analytical signal, when compared with GCE, again demonstrating an electrocatalytic effect. Under optimized experimental conditions, the developed square-wave adsorptive anodic stripping voltammetry (SWAdASV) method presented an analytical curve that was linear in RNT concentration range from 1.98 × 10?6 to 2.88 × 10?5 mol L?1 with a detection limit of 2.44 × 10?7 mol L?1. The developed Printex6L/GCE was successfully applied to the determination of RNT concentrations in human body fluid samples (urine and serum). 相似文献
56.
The use of two different monoliths located in capillaries for on-line protein digestion, preconcentration of peptides and their separation has been demonstrated. The first monolith was used as support for covalent immobilization of pepsin. This monolith with well-defined porous properties was prepared by in situ copolymerization of 2-vinyl-4,4-dimethylazlactone and ethylene dimethacrylate. The second, poly(lauryl methacrylate-co-ethylene dimethacrylate) monolith with a different porous structure served for the preconcentration of peptides from the digest and their separation in reversed-phase liquid chromatography mode. The top of the separation capillary was used as a preconcentrator, thus enabling the digestion of very dilute solutions of proteins in the bioreactor and increasing the sensitivity of the mass spectrometric detection of the peptides using a time-of-flight mass spectrometer with electrospray ionization. Myoglobin, albumin, and hemoglobin were digested to demonstrate feasibility of the concept of using the two monoliths in-line. Successive protein injections confirmed both the repeatability of the results and the ability to reuse the bioreactor for at least 20 digestions. 相似文献
57.
Artuso M Goldberg M Horwitz N Kennett R Moneti GC Muheim F Playfer S Rozen Y Rubin P Stone S Thulasidas M Yao W Zhu G Barnes AV Bartelt J Csorna SE Egyed Z Jain V Sheldon P Akerib DS Barish B Chadha M Cowen DF Eigen G Miller JS Urheim J Weinstein AJ Acosta D Masek G Ong B Paar H Sivertz M Bean A Gronberg J Kutschke R Menary S Morrison RJ Nelson H Richman J Tajima H Schmidt D Sperka D Witherell M Procario M Yang S Daoudi M Ford WT Johnson DR Lingel K Lohner M Rankin P Smith JG Alexander JP 《Physical review letters》1992,69(23):3278-3281
58.
Jürgen Geiser 《PAMM》2006,6(1):739-740
In this paper we consider parabolic equations with multi-physical processes for applications in porous media. For the solver method we apply an overlapping Schwarz wave form relaxation method, see [1]. We describe the theory for a multidimensional convection-diffusion-reaction equations and present an error-estimate for the domain-decomposition-method. The exactness and the efficiency of the methods are investigated through solutions of model problems of convection-diffusion-reaction equation. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
59.
Dany Spaggiari Laurent Geiser Youssef Daali Serge Rudaz 《Analytical and bioanalytical chemistry》2014,406(20):4875-4887
The cocktail approach is an advantageous strategy used to monitor the activities of several cytochromes P450 (CYPs) in a single test to increase the throughput of in vitro phenotyping studies. In this study, a cocktail mixture was developed with eight CYP-specific probe substrates to simultaneously evaluate the activity of the most important CYPs, namely, CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and the CYP3A subfamily. After cocktail incubation in the presence of human liver microsomes (HLMs), the eight selected substrates and their specific metabolites were analyzed by ultra-high-pressure liquid chromatography and electrospray ionization quadrupole time-of-flight mass spectrometry. Qualitative and quantitative data were simultaneously acquired to produce an overview of the extended phase I biotransformation routes for each probe substrate in the HLMs and to generate phenotypic profiles of various HLMs. A comparison of the cocktail strategy with an individual substrate assay for each CYP produced similar results. Moreover, the cocktail was tested on HLMs with different allelic variants and/or in the presence of selective inhibitors. The results were in agreement with the genetic polymorphisms of the CYPs and the expected effect of the alterations. All of these experiments confirmed the reliability of this cocktail assay for phenotyping of the microsomal CYPs. 相似文献
60.
Bartelt J Csorna SE Egyed Z Jain V Kinoshita K Barish B Chadha M Chan S Cowen DF Eigen G Miller JS O'Grady C Urheim J Weinstein AJ Acosta D Athanas M Masek G Paar HP Sivertz M Gronberg J Kutschke R Menary S Morrison RJ Nakanishi S Nelson HN Nelson TK Qiao C Richman JD Ryd A Tajima H Sperka D Witherell MS Procario M Balest R Cho K Daoudi M Ford WT Johnson DR Lingel K Lohner M Rankin P Smith JG Alexander JP Bebek C Berkelman K Bloom K Browder TE Cassel DG Cho HA Coffman DM Crowcroft DS Drell PS 《Physical review letters》1994,73(14):1890-1894