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61.
62.
Anjos JC Appel JA Bean A Bediaga I Bracker SB Browder TE Cremaldi LM Duboscq JE Elliot JR Escobar CO Gibney MC Hartner GF Karchin PE Kumar BR Lima JG Losty MJ Luste GJ Mantsch PM Martin JF McHugh S Menary SR Morrison RJ Nash T Pinfold J Punkar G Purohit MV Ross WR Santoro AF Sliwa K Sokoloff MD Souza MH Spalding WJ Streetman ME Stundzia AB Witherell MS 《Physical review letters》1992,69(20):2892-2895
63.
A system has been developed for online preconcentration and determination of Cd using thermospray flame furnace atomic absorption
spectrometry (TS-FF-AAS). It is based on the solid-phase extraction of Cd in an Amberlite XAD-2 minicolumn loaded with 2-(2-thiazolylazo)-5-dimethylaminophenol
(TAM), and the metal ion is eluted with 1 mol L−1 hydrochloridric acid, followed by its determination. The online system allows determining Cd with a detection limit of 8.0 ng L−1 and a quantification limit of 25.0 ng L−1. The precision (repeatability), calculated as the relative standard deviation (% RSD) in sample solutions containing 0.5
and 3.0 μg L−1 of Cd, was 6.1 and 4.5%, respectively. The preconcentration factor obtained was 24. The system’s accuracy was confirmed by
analyzing the following certified reference materials (CRMs): Rice flour NIES 10b, Apple leaves NIST 1515 and Orchard leaves
NBS 1571. This procedure was applied to the determination of Cd in cabbage and powdered guarana samples. 相似文献
64.
A252Cf neutron source has been used to analyse manganese in ores such as pyrolusite, rodonite (manganese silicate) and blends used in dry-batteries. Samples with about 150 mg and standards of manganese dioxide were irradiated for about 20 min and counted using a well-type NaI(Tl) scintillation counter and scaler, with or without pulse-height discriminator between the detector and the scaler. The interferences of nuclear reactions56Fe(n,p)56Mn and59Co(n,α)56Mn were studied, as well as problems in connection with neutron shadowing during irradiation, gamma-rays attenuation during counting and influence of granulometry of samples. Some of the samples were also analysed by wet-chemical method (sodium bismuthate) in order to compare results. 相似文献
65.
In this work a simple, fast, sensitive and selective flow-based procedure for the chemiluminometric determination of carvedilol, a recent non-cardioselective β-blocker with noteworthy antioxidant activity, is proposed. The developed methodology takes advantage of the antioxidant capacity of carvedilol to inhibit the chemiluminescence response resulting from the oxidation of luminol by hypochlorite, by acting as a hypochlorite scavenger. The analytical process was implemented in a multi-pumping flow system that employs multiple solenoid actuated micro-pumps as the only active components. These acted as solution insertion, propelling and commuting units assuring an easily controlled, low cost, compact and reliable analytical system.A linear working range for carvedilol concentrations ranging from 1.2 × 10−7 to 3.0 × 10−6 mol l−1 (r > 0.999, n = 6), was obtained, with a detection limit of 8.7 × 10−9 mol l−1. The system handles about 65 samples per hour yielding precise results (R.S.D. < 1.3%, n = 10). Recoveries within 95 and 104% were obtained. 相似文献
66.
Camila L. de Camargo Letícia S. ShiromaGabriela F. Giordano Angelo L. GobbiLuis C.S. Vieira Renato S. Lima 《Analytica chimica acta》2016
This paper addresses an important breakthrough in the deployment of ultra-high adhesion strength microfluidic technologies to provide turbulence at harsh flow rate conditions. This paper is only, to our knowledge, the second reporting on the generation of high flow rate-assisted turbulence in microchannels. This flow solves a crucial bottleneck in microfluidics: the generation of high throughput homogeneous mixings. We focused on the fabrication of bulky polydimethylsiloxane (PDMS) microchips (without any interfaces) rather than the laborious surface modifications that were employed in the first reporting about turbulence-assisted microfluidics. The fabrication is cleanroom-free, simple, low-cost, fast, solventless, and bondless requiring only a laboratory oven. More specifically, our method relies on the shaping of a nylon scaffold, cure of PDMS with embedded nylon, and removal of this scaffold. The scaffold was obtained by manually wrapping nylon threads. The withdrawing out of the scaffold was completed in few seconds using only a plier. Such microchannels endured flow rates of up to 60.0 mL min−1 with a strikingly low elastic deformation. The importance in producing turbulence into microscale channels was successfully shown in liquid-liquid extractions. The great energy dissipation rate relative to the turbulence created high throughput and efficient extractions in microfluidics for the first time. The residence time was only 0.01 s at 25.0 mL min−1 (total flow rate of the immiscible phases). In addition, the partition coefficient determined in a single run was similar to that obtained by the conventional batch shake-flask method that was realized in triplicate. 相似文献
67.
68.
Suely L. Galdino Maria C. A. Lima Alexandre J. S. Góes Ivan R. Pitta Cuong Luu-Duc 《光谱学快报》2013,46(7-8):1013-1021
In the present investigation, a study of the electron impact mass spectrometry data is reported for seven compounds of a series of some 3-(4-chlorobenzyl)-5-benzylidene-imidazolidine-2, 4-diones and 3-(4-fluoro or chlorobenzyl)-5-benzylidene-thiazolidine-2, 4-diones previously synthesized. 相似文献
69.
70.
Marcela S. O. Wanderley Carla Oliveira Danyelly Bruneska Lucília Domingues José L. Lima Filho José A. Teixeira Solange I. Mussatto 《Chemical Papers》2013,67(7):682-687
Frutalin, a galactose-specific lectin used to detect specific tumour markers, is a protein with low expression level in breadfruit. In the present study, fed-batch fermentation in a stirred tank bioreactor was used as a strategy to enhance protein production by a recombinant Pichia pastoris KM71H. By using this process, the production of recombinant frutalin was 4-fold higher than the value obtained in shaker flasks batch assays. Supplementation of the fermentation medium with trace elements (Pichia trace minerals, PTM) was also evaluated in order to stimulate production of the recombinant protein. The addition of PTM to the minimum medium afforded a recombinant protein production of 13.4 mg L?1, which was 2.5-fold higher than that achieved from the culture medium without PTM supplementation. These results are significant as the development of strategies to improve the production of recombinant frutalin may broaden its application in cancer diagnosis. 相似文献