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41.
This study presents a novel separation, preconcentration and determination of basic fuchsin (BF) in an aqueous solution by sodium dodecyl sulfate (SDS)-bounded iron oxide nanoparticles (S-IONPs). It is shown that the novel magnetic nano-adsorbent is quite efficient for the adsorption and desorption of BF at 25 °C. Different parameters such as pH, temperature, ionic strength and composition of desorbent solvent were optimized. The effect of some co-existing ions on the determination was investigated. The nanoparticles were analyzed by transmission electron microscopy (TEM) and the sizes of S-IONPs were in the range of 20-100 nm. The method showed good linearity for the determination of BF in the range of 10-300 ng mL−1 with a regression coefficient of 0.9989. The limit of detection (LOD) (signal-to-noise ratio of 3:1) was 0.0073 μg L−1 and the relative standard deviation (RSD) for 0.03 μg mL−1 and 0.2 μg mL−1 of BF were 4.53% and 4.73%, respectively. The BF was determined successfully in spiked samples of Karoon River water. 相似文献
42.
研究了混合稀土储氢合金中氧和氮的测定方法。针对稀土金属高温易挥发、分解的特点,选择适宜的加热温度,使用镍浴,选择高温座坩埚进行试验:选择出了合适的助熔剂的预处理方法。方法已用于实际样品。对含氧0.43%、含氮0.018%的试样,分析精密度为氧4.3%,氮5.9%,加标回收率氧为93%~104%,氮为92%~110%。 相似文献
43.
Atom interferometry gravity-gradiometer for the determination of the Newtonian gravitational constant G 总被引:1,自引:0,他引:1
A. Bertoldi G. Lamporesi L. Cacciapuoti M. de Angelis M. Fattori T. Petelski A. Peters M. Prevedelli J. Stuhler G. M. Tino 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(2):271-279
We developed a gravity-gradiometer based on atom interferometry for the determination of the Newtonian gravitational constant
G.
The apparatus, combining a Rb fountain, Raman interferometry and a juggling scheme for fast launch of two atomic clouds, was
specifically
designed to reduce possible systematic effects. We present instrument performances and preliminary results for the measurement
of G with a relative uncertainty of 1%. A discussion of projected accuracy for G measurement using this new scheme shows
that the results of the experiment will be significant to discriminate between previous inconsistent values. 相似文献
44.
Eberhard Reimann Wolfgang Erdle Eugen Hargasser Hermann Lotter 《Monatshefte für Chemie / Chemical Monthly》2002,133(7):1017-1030
Summary. The stereoselective synthesis of cis-ergoline is presented. Starting from rac-N-benzoyl tryptophan methyl ester, the key compound indolinylmethylpyridin-3-one was prepared via a seven-step reaction in good yield. Since its cyclization to the desired ergolinone failed, the key compound was reduced
to yield the two diastereomeric pyridin-3-ols; only one of them cyclized in trifluoromethanesulfonic acid, affording cis-ergoline. Catalytic hydrogenation of the latter gave N,N′-dimethyldihydroergoline, the X-ray crystallography of which revealed both the correct structure and identical relative configurations
at C-5a and C-6a (SS or RR). Hydroboration and subsequent perruthenate oxidation of the Δ9-ergoline provided access to the regioisomeric ergolinols and ergolinones.
Received December 27, 2001. Accepted January 15, 2002 相似文献
45.
M. C. Recchioni 《Journal of Optimization Theory and Applications》1995,86(1):223-244
The modified Newton method for multiple roots is organized in an interval method to include simultaneously the distinct roots of a given polynomialP in complex circular interval arithmetic. A condition on the starting disks which ensures convergence is given, and convergence is shown to be quadratic. As a consequence, a simple parallel algorithm to approach all the distinct roots ofP is derived from the modified Newton method.The research reported in this paper has been made possible through the support and the sponsorship of the Italian Government through the Ministero per l'Universitá e la Ricerca Scientifica under Contract MURST 60%, 1990 at the Universitá di L'Aquila. 相似文献
46.
本文研究了用自制Ni(CO)4发生管和电加热石英管原子化器间接测定一氧化碳的条件,探讨了Ni(CO)4的产生和在石英管中原子化效率及干扰消除。 相似文献
47.
对注射用盐酸阿糖胞苷采用旋光法进行测定,测定管长为1 cm。当盐酸阿糖胞苷浓度在1~9.000 0 g.L-1之间时,旋光度与浓度呈线性关系,回归方程为α=0.130 1C+0.000 1,相关系数为0.999 9,平均回收率为99.93%,RSD为0.47%。方法简便、快速、准确,适合于药厂、医院对产品及制剂的快速分析。 相似文献
48.
Imdad Ullah Mohammadzai Tomoko Ashiuchi Satoshi Tsukahara Yasuaki Okamoto Terufumi Fujiwara 《中国化学会会志》2005,52(5):1037-1042
A simple and fast flow method for the trace level determination of p‐toluidine, 2‐methyl‐5‐nitroaniline, and 2,4‐dinitroaniline in aqueous samples is reported. These amino/nitroaromatics are related to trinitrotoluene (TNT) and appear during the degradation process of the explosive. The chemical principles of ion‐pair formation and liquid‐liquid extraction are applied: In aqueous acidic medium, the protonated analyte [HA]+ makes an ion‐pair with the tetrachloroaurate(III) ion, followed by on‐line ion‐pair extraction into the dichloromethane carrier used. After membrane separation, the CH2Cl2 containing the ion‐pair, [HA]+[AuCl4]−, is mixed with the reversed micellar luminescent reagent of luminol (in 0.3 M Na2CO3) prepared from cetyl‐trimethylammonium chloride in CH2Cl2‐cyclohexane and the [AuCl4−‐luminol chemiluminescence (CL) output is recorded. The detection limits (S/N> 3) are: p‐toluidine, 1.0 × 10−4M; 2‐methyl‐5‐nitroaniline, 1.0 × 10−7 M; 2,4‐dinitroaniline, 1.0 × 10−7 M, while the calibration curves are linear between 1.0 × 10−4 — 1.0 × 10−2 M for all the compounds. Although spectral studies indicated the formation and extraction of a very small amount of the ion‐pair species, the reversed micellar‐mediated CL detection system provides an alternative procedure for the determination of degradation products of the explosive TNT in environmental aqueous samples. 相似文献
49.
50.
原子吸收光谱间接测定色氨酸的研究 总被引:1,自引:1,他引:0
色氨酸(Tryptophan,Trp)在碱性条件下与新生成的ZnS悬浮液反应,生成可溶性碱式色氨酸锌配合物,再用塞曼原子吸收光谱测定溶液中的总锌浓度即可间接的得到色氨酸的含量.优化了测定的最佳条件,在pH 9.10的2%硼砂底液中于室温下,使色氨酸试液与新生成的ZnS悬浮液反应22min,离心分离后测定上层清液的FAAS响应.在所选定的条件下色氨酸测定的线性浓度范围为0-18.5mg·mL-1,特征浓度为0.219mg·mL-1,检出限为1.414mg·mL-1.该法用于样品中的色氨酸测定,其相对标准偏差RSD为4.12%,方法的回收率在70.1%-120.3%之间.并对测定机理进行了探讨. 相似文献