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31.
De Oliveira MF Saczk AA Okumura LL Fernandes AP De Moraes M Stradiotto NR 《Analytical and bioanalytical chemistry》2004,380(1):135-140
A new, versatile, and simple method for quantitative analysis of zinc, copper, lead, and cadmium in fuel ethanol by anodic stripping voltammetry is described. These metals can be quantified by direct dissolution of fuel ethanol in water and subsequent voltammetric measurement after the accumulation step. A maximum limit of 20% (v/v) ethanol in water solution was obtained for voltammetric measurements without loss of sensitivity for metal species. Chemical and operational optimum conditions were analyzed in this study; the values obtained were pH 2.9, a 4.7-m thickness mercury film, a 1,000-rpm rotation frequency of the working electrode, and a 600-s pre-concentration time. Voltammetric measurements were obtained using linear scan (LSV), differential pulse (DPV), and square wave (SWV) modes and detection limits were in the range 10–9–10–8 mol L–1 for these metal species. The proposed method was compared with a traditional analytical technique, flame atomic absorption spectrometry (FAAS), for quantification of these metal species in commercial fuel ethanol samples. 相似文献
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Electroactive nickel(II) hexacyanoferrate (NiHCF) thin film modified electrodes are effective potentiometric sensors for the determination of potassium ions. The NiHCF films are deposited onto glassy carbon electrodes by repetitive potential cycling in K(3)Fe(CN)(6)/NaNO(3)/Ni(NO(3))(2) solution. The modified electrodes exhibit a linear response to potassium ions in the concentration range 1x10(-3) to 2.0 mol dm(-3), with a near-Nernstian slope (45-49 mV per decade) at 25 degrees C. In the determination of potassium ion in syrups used for treatment of potassium deficiency, the NiHCF-modified electrode gave comparable results to those obtained using flame emission spectrophotometry. 相似文献
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(N‐Phosphinoamidinate)cobalt‐Catalyzed Hydroboration: Alkene Isomerization Affords Terminal Selectivity 下载免费PDF全文
Adam J. Ruddy Dr. Orson L. Sydora Dr. Brooke L. Small Prof. Dr. Mark Stradiotto Prof. Dr. Laura Turculet 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(43):13918-13922
Herein we establish the utility of a three‐coordinate (N‐phosphinoamidinate)cobalt(amido) pre‐catalyst that is capable of effecting challenging alkene isomerization/hydroboration processes at room temperature, leading to the selective terminal addition of the boron group. 相似文献
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Synthesis and Reactivity of a Neutral,Three‐Coordinate Platinum(II) Complex Featuring Terminal Amido Ligation 下载免费PDF全文
Colin M. Kelly Doo‐Hyun Kwon Dr. Michael J. Ferguson Dr. Steven M. Bischof Dr. Orson L. Sydora Prof. Dr. Daniel H. Ess Prof. Dr. Mark Stradiotto Prof. Dr. Laura Turculet 《Angewandte Chemie (International ed. in English)》2015,54(48):14498-14502
A crystallographically characterized three‐coordinate, formally 14 electron PtII complex 1 featuring terminal amido ligation is reported. Computational analysis revealed relatively weak π donation from the amide lone pair to platinum and supports a 14‐electron assignment for 1 . Stoichiometric reactivity studies confirmed the viability of net O? H and C? H addition across, as well as isonitrile insertion into, the terminal platinum–amido linkage of 1 . 相似文献
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A novel, inexpensive and fast method based on the electrooxidation of glycerol on platinum electrodes by the potential cycling technique has been designed for the determination of free glycerol in biodiesel. A wide range of linearity was achieved between 15 and 150 mg L−1 (0.16 and 1.6 mmol L−1), which corresponds to concentrations ranging between 56 and 560 mg kg−1 (glycerol:biodiesel) for an extraction using 2 g biodiesel. A method for the fast extraction of glycerol from biodiesel with water followed by elimination of organic interferents has also been developed, so that the novel determination method can be applied to various biodiesel samples. The excellent repeatability allows determination of glycerol in numerous samples, with no need for recalibration. 相似文献
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Corrigendum: (N‐Phosphinoamidinate)cobalt‐Catalyzed Hydroboration: Alkene Isomerization Affords Terminal Selectivity 下载免费PDF全文
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Studies of the complexation of Sn(II) by N,N-dimethylformamide show that Sn(II) ion forms six successive complexes with the ligand. The stability constants were determined by the method of DeFord and Hume. The free energy of transfer of Sn(II) from acetonitrile to N,N-dimethylformamide and to their mixtures was obtained using the theory of Cox et al. The energy decreases with increasing N,N-dimethylformamide concentration, the decrease being most pronounced for nearly pure acetonitrile. 相似文献
40.
V. S. Rodgher L. L. Okumura A. A. Saczk N. R. Stradiotto M. V. B. Zanoni 《Journal of Analytical Chemistry》2006,61(9):889-895
The voltammetric reduction of acetaldehyde was studied in 0.1 M LiOH: LiCl (60: 40 v/v). Well-defined waves can be seen at
−1.77 and −1.60 V with the use of hanging mercury and glassy carbon electrodes. Acetaldehyde was shown to react at room temperature
with the 2,4-dinitrophenylhydrazine and the product exhibited a differential pulse voltammetric peak at −0.90 V, which was
well separated from the peaks of the derivative. This allowed the indirect determination of acetaldehyde in the presence of
0.1 M ethanol/tetrabutylammonium perchlorate after 10 min of reaction. Calibration graphs were obtained for 1.00 × 10−6−1.00 × 10−4 M of acetaldehyde. The detection limit is 8.14 × 10−7 M. The method has been applied satisfactorily to the determination of total aldehyde in fuel ethanol samples without any
pretreatment.
The text was submitted by the authors in English. 相似文献