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101.
102.
A method for the determination of fluoride by reversed-phase, high-performance liquid chromatography (RP-HPLC) is described. Fluoride, La3+ and alizarin complexone form F-La3+-alizarin complexone ternary complex, which is separated from the matrix on a RP, Ultrasphere C18 column (250 × 4.6 mm, 5 μm) using methanol-water (19:81, v/v) mobile phase at 1.00 mL min?1; detection at 568 nm. The calibration graph was linear from 1.0–150 ng mL?1 for fluoride with a correlation coefficient: 0.9993 (n=6). The detection limit was 0.2 ng mL?1. The method was successfully applied to the determination of fluoride in river and tap water. Recovery was: 94–102%, RSD in the range: 1.9 –3.6%. 相似文献
103.
对铝原子簇Al_n(n=1~10,12,13)已报导过的理论预测几何构型进行合理选择, 用量子化学CNDO/2法研究了单分子一氧化碳在这些簇上取不同吸附位形时的吸附作用。结果表明吸附强度随簇尺度的变化呈“幻数”特性: Al_2、Al_6、Al_(12)簇具有特别高的吸附能, 与实验观测结果相符。采用作者建议的推广电子壳模型可合理解释这一尺度效应。对Al_(12)和Al_(13)簇电子结构的分析进一步支持了壳模型的观点。随着簇的增大, 尺度效应逐步减弱并趋向于体相铝的性质。 相似文献
104.
A sol-gel chemistry-based polymer coating approach was developed for the preparation of a novel polysiloxane-coated silica stationary phase for capillary liquid chromatography. SE-30, a commercial polysiloxane stationary phase used in gas chromatography, was incorporated into the properly designed sol solution. Then the sol-gel mixture was introduced into a silica gel-packed capillary column by pressure. A thin film of sol-gel SE-30-coating is chemically bonded to the surface of silica gel particles by hydrolytic polycondensation under mild conditions without any free radical cross-linking procedures, therefore the sol-gel approach offers a simple and effective pathway to create a hybrid polymer-coated silica stationary phase. Various factors affecting column making were optimized and discussed in this report. The resulting stationary phase showed good permeability, mechanical robustness, high durability to alkaline mobile phase and satisfactory chromatographic performance in separations of polar and non-polar aromatic compounds. Linear solvation energy relationships (LSERs) studies indicate that the stationary phase has a reversed-phased character with SE-30 providing chromatographic functionality. The solute size and the solute hydrogen bond ability are major factors that principally govern the retention of test solutes. 相似文献
105.
CBr_4和CCl_4分子的解离反应前人已做了许多工作,他们分别采用射频放电、电子轰击、He~ 的传能反应等方法研究了CCl_4和CBr_4的解离反应,得到了CCI(A)、CCl~ 、CBr~ 等碎片的发射光谱。有关亚稳态原子与它们的传能反应,只有某些较简单的报道,对传能反应机理也未作深入探讨。本文研究了各种亚稳态原子He(2~3S)、Ne(~3P_(0.2))、Ar(~3P_(0.2))与CCl_4和CBr_4分子的传能反应,并对反应机理进行了初步的讨论和分析。 相似文献
106.
107.
用流动反应法和TPSRMS等技术研究了CO在Pd/γAl2O3和含有ZrO2的催化剂上的吸脱附行为、表面反应及催化氧化活性,同时用XRD技术测定了催化剂的物相结构。结果表明,在Pd/γAl2O3催化剂中用浸渍法添加ZrO2或掺杂超细ZrO2后,催化剂的氧化活性均有明显提高;COTPSR的实验结果表明,CO在氧化态Pd催化剂上程序升温脱附过程中主要与表面氧发生氧化反应,而在还原态Pd催化剂上发生歧化反应,并发现CO2的脱附量及脱附峰温次序与对CO的氧化活性有一致的对应关系。 相似文献
108.
A chemically bonded cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phase (CSP) was prepared by a radical polymerization reaction. The prepared CSP was packed into fused-silica capillaries with inner diameter of 75 microm to perform enantiomer separations in CEC. The electrochromatographic behavior of the CSP was investigated. On the prepared CSP, high EOF could be generated under acidic mobile phases, which represented an advantage for the separation of acidic enantiomers. Several neutral, acidic, and basic enantiomers were resolved on the prepared CSP under aqueous mobile phases. The column efficiencies were between 20,000 and 100,000 plates/m, which were much higher than those of HPLC. In addition, it was observed that the separation of some enantiomers benefited from the adoption of THF as mobile phase modifier. 相似文献
109.
Bian HD Gu W Xu JY Bian F Yan SP Liao DZ Jiang ZH Cheng P 《Inorganic chemistry》2003,42(14):4265-4267
The first mu(3)-oxalato-bridged copper(II) complex, [[Cu(3)(L)(3)(mu(3)-C(2)O(4))][Cu(L)(H(2)O)](ClO(4))(2)] x 0.5(H(2)O) x 0.5(CH(3)OH), where HL = N-ethyl-N'-salicylidene-1,2-diaminoethane, has been synthesized and characterized by variable-temperature magnetic susceptibility measurement. The complex exhibits ferromagnetic coupling between the oxalato-bridged copper atoms and antiferromagnetic coupling between the oxygen-bridged copper atoms. 相似文献
110.
A comb-structured polymeric flocculant was synthesized by the aqueous copolymerization of N-vinylformamide (NVF) with poly(dimethylaminoethyl methacrylate) quats (methyl chloride) macromonomer. The effects of temperature
and macromonomer concentration on the copolymerization kinetics were determined experimentally. The copolymerization reactivity
ratio was measured to be 3.82 and 6.39 for NVF and macromonomers with 50 and 100 repeating units when copolymerized with NVF.
The copolymer samples were also subjected to a flocculation performance test and were found to be more effective than linear
random cationic copolymers in terms of cationic content, flocculation rate, final turbidity levels, and floc strength.
Received: 11 June 2001 Accepted: 9 August 2001 相似文献