共查询到20条相似文献,搜索用时 58 毫秒
1.
2.
3.
4.
5.
固相萃取富集-高效液相色谱分离和测定邻甲苯胺和邻硝基甲苯 总被引:5,自引:0,他引:5
建立了以固相萃取技术进行富集 ,高效液相色谱进行分离和检测邻甲苯胺和邻硝基甲苯的方法。污染水中的邻甲苯胺和邻硝基甲苯采用Sep pakC1 8萃取柱进行固相萃取。色谱分离条件是 :Shim PackCLCODS(1 5 0mm× 4 .6mmid ,5 μm)柱为分析柱 ,甲醇 水 =60∶4 0 (V V)为流动相 ,流速为 1 .0mL min,邻甲苯胺和邻硝基甲苯的紫外检测波长分别为 2 3 0nm和 2 5 4nm ,本法具有良好的灵敏度和重现性。 相似文献
6.
7.
8.
9.
采用高分辨质谱仪跟踪监测对硝基甲苯在多硫化钠存在下于乙醇-碱性水溶液中生成对氨基苯甲醛过程中反应中间体的变化及转变规律.结果显示,在80℃时反应进行到120min之内,有数种分子量较大的缩合中间体生成,表明对氨基苯甲醛可能是经类席夫碱的多聚体水解生成的.同时,对席夫碱多聚体的形成提出了与文献不同的机理. 相似文献
10.
11.
Ive Hermans Dr. Jozef Peeters Prof. Dr. Luc Vereecken Dr. Pierre A. Jacobs Prof. Dr. 《Chemphyschem》2007,8(18):2678-2688
Aerobic oxidation of toluene (PhCH3) is investigated by complementary experimental and theoretical methodologies. Whereas the reaction of the chain‐carrying benzylperoxyl radicals with the substrate produces predominantly benzyl hydroperoxide, benzyl alcohol and benzaldehyde originate mainly from subsequent propagation of the hydroperoxide product. Nevertheless, a significant fraction of benzaldehyde is also produced in primary PhCH3 propagation, presumably via proton rather than hydrogen transfer. An equimolar amount of benzyl alcohol, together with benzoic acid, is additionally produced in the tertiary propagation of PhCHO with benzylperoxyl radicals. The “hot” oxy radicals generated in this step can also abstract aromatic hydrogen atoms from PhCH3, and this results in production of cresols, known inhibitors of radical‐chain reactions. The very fast benzyl peroxyl‐initiated co‐oxidation of benzyl alcohol generates HO2. radicals, along with benzaldehyde. This reaction also causes a decrease in the overall oxidation rate, due to the fast chain‐terminating reaction of HO2. with the benzylperoxyl radicals, which causes a loss of chain carriers. Moreover, due to the fast equilibrium PhCH2OOH+HO2.?PhCH2OO.+H2O2, and the much lower reactivity of H2O2 compared to PhCH2OOH, the fast co‐oxidation of the alcohol means that HO2. gradually takes over the role of benzylperoxyl as principal chain carrier. This drastically changes the autoxidation mechanism and, among other things, causes a sharp decrease in the hydroperoxide yield. 相似文献
12.
Benedikt Galliker Reinhard Kissner Thomas Nauser Willem H. Koppenol Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(25):6161-6168
ONOO. is an important intermediate in the autoxidation of nitrogen monoxide by dioxygen. A formerly unknown red isomer of N2O4, ONOONO (see figure), formed in 2‐methylbutane at 113 K from nitrogen monoxide and dioxygen, is converted to O2NNO2 upon warming.
13.
本文设计了一种适用于各种萃取体系并能与原子光谱仪和分光光度计联用的FI液液萃取重力分相器.用该分相器分别研究了FI-MIBK萃取-FAAS测定金和FI-CCl4萃取-分光光度法测定碘的分析性能.结果表明,该分相器操作简单,分相完全,是一种较理想的重力分相器 相似文献
14.
精氨酸-甘氨酸-天冬氨酸(RGD)是近年来发现的具有较高应用价值的生物活性短肽,可抑制肿瘤细胞与内皮细胞和基底膜的粘附,加速肿瘤细胞脱附,阻止肿瘤细胞滞留,从而抑制肿瘤细胞的转移。研究RGD序列肽的合成具有重要意义。本文以氯乙酰氯和天冬氨酸为原料经缩合、胺化合成GD二肽,其纯度为98.6%,产率约为84.8%。然后采用液相N-羧基内酸酐化学法合成了游离的RGD三肽,其纯度为94.2%,产率约为71.4%。采用红外光谱、质谱、高效液相色谱等手段对中间产物及RGD三肽进行了表征和分析,证实产物结构正确。 相似文献
15.
低温液相制备金红石型TiO2纳米晶须 总被引:3,自引:0,他引:3
目前,已有多种控制TiO2形貌及晶须生长的方法,如模板合成、超分子组装、声化学合成液相法及固相合成等,其中,液相法是最为廉价和简单的方法.为此,近期采用低温液相法合成金红石型TiO2受到了极大的关注.本文在以前工作的基础上,采用改进的实验方法通过在低温陈化一定浓度的TiCl4水溶液直接获得了金红石型TiO2纳米晶须,并对产物进行了初步表征. 相似文献
16.
The mechanism of perovskite 0.1Pb(Mg1/2W1/2)O3-0.6Pb(Ni1/3Nb2/3)O3-0.3PbTiO3 (abbreviated PMW-PNN-PT) phase formation by Semichemical Method has been studied. The precursors were prepared by adding aqueous solution of Mg(Ac)2 and Ni(AC)2 rather than solid MgO and NiO to the alcoholic slurry of PbO, WO3, Nb2O5 and TiO2. The TG-DTG and DSC of the precursors and XRD analysis of the powders at various calcination temperature showed that the mechanism of this method was different from that of the conventional mixed oxide method. The aqueous Mg(Ac)2 and Ni(Ac)2 reacted with PbO to form basic lead acetate, basic magnesium acetate and basic nickel acetate and so on. With the increase of calcination temperature these basic salt decomposed to form nascent PbO, MgO and NiO, which improved the reactivity and distribution of PbO, MgO and NiO. In addition, the formation of PbWO4 and pyrochlore phase Pb3Nb2O8 in the process was in favor of the pervoskite PMW-PNN-PT phase formation. At the calcining temperature of 850 ℃, the perovskite phase reached 98%. 相似文献
17.
含Sc*相硅碳烷树枝状分子液晶 总被引:1,自引:0,他引:1
树枝状化合物具有规整的结构,其分子体积、形状和功能基可在分子水平上精确控制[1].它的出现对于经典的有机高分子界是一个冲击,它是化学、生命科学和材料科学等多学科的交叉点,成为当前学术界的一大研究热点.我国这方面的研究起步较晚,至今仅有陈永明[2]、薄志山[3]和我们[4]曾报道过树状物. 相似文献
18.
19.
多孔中空纤维液相微萃取技术的研究进展 总被引:4,自引:0,他引:4
基于多孔中空纤维的液相微萃取集采样、萃取和浓缩于一体,具有成本低,易与多种分析仪器联用等特点,该技术不仅可得到较高的富集倍数和回收率,而且具有突出的样品净化功能,有机溶剂用量非常少,是一种环境友好的样品前处理新技术,国内尚未广泛应用。本文综述了多孔中空纤维液相微萃取的主要装置、萃取模式、影响因素及其应用,引用文献54篇。 相似文献
20.
单质铁纳米颗粒的液相还原制备 总被引:4,自引:0,他引:4
采用水合肼作还原剂, 在有柠檬酸存在的情况下, 以FeCl2为铁源, 通过液相化学还原制备粒径为15~50 nm的单质铁纳米颗粒. 采用X射线衍射(XRD)、X射线能谱仪(EDS)和场发射扫描电镜(FESEM)对制备的Fe纳米粒子的结构、组成和形貌进行了表征, 并使用超导量子干涉仪(SQUID)对制备的Fe纳米粒子的磁学性能进行了表征. 研究结果表明, 在柠檬酸存在下, 可以用肼在常温常压下液相还原亚铁离子制备出单质铁纳米颗粒, 改变络合剂后还原无法进行, 并对可能的反应机理进行了讨论. 相似文献