新试剂HABST分光光度法测定铜

硫脲类试剂因含有Ｓ ,Ｎ配位原子而可与无机离子形成配合物 ,近年来已被用于定性分析和定量测定。对氨基苯磺酸钠类硫脲因其良好的水溶性而避免了以往测铜试剂需有机相中进行的繁琐处理。Ｎ 庚基 Ｎ′ (对氨基苯磺酸钠 )硫脲(ＨＡＢＳＴ) [1 ] 是继Ｎ 烯丙基 Ｎ′ (对氨基苯磺酸钠 )硫脲 (ＡＳＡＴＵ) [2 ] 后又合成的一种水溶性光度试剂 ,通过初步研究 ,发现它与Ａｇ+、Ｃｕ2 +有特征性反应。在此基础上 ,对其与铜的显色反应作进一步研究 ,探讨了ＨＡＢＳＴ分光光度法测定铜的最佳条件 ,在ｐＨ4.5～ 6.0的ＨＡｃ ＮａＡｃ缓冲溶液中 ,Ｃ…     

2-(1,3,4-三氮唑偶氮)-5-二乙氨基苯甲酸光度法测定钒

有机偶氮类显色剂与钒 (Ｖ)形成络合物的分光光度法测定钒 ,灵敏度或选择性不高[1 ,2 ] ,我们曾合成了三氮唑偶氮类显色剂ＴＺＡＰＮ[3] 和ＣＴＺＡＰＮ[4] 以及四氮唑偶氮类显色剂ＴＺＡＤＡＰ[5] ,用于光度法测定钒 ,效果较好。为了进一步考察试剂结构对金属离子显色反应灵敏度和选择性的影响 ,以便筛选灵敏度和选择性更好的试剂 ,我们又设计合成了 2 ( 1 ,3,4 三氮唑偶氮 ) 5 二乙氨基苯甲酸 (简称ＴＺＤＢＡ)。探讨其与钒 (Ｖ)的显色反应条件 ,并用于铝合金样品及合成废水中钒的直接测定 ,结果令人满意。1　实验部分仪器 :ＵＶ - 2 4…     

低压离子色谱法测定CeO2产品中微量氟的研究

采用氟碳铈矿为原料冶炼成的稀土氧化物产品中 ,氟含量的测定在检验稀土产品纯度中起着重要的作用。目前此类产品中氟含量的测定主要有二甲酚橙 锆退色法和氟试剂法[1 ] 。而采用低压离子色谱法分析稀土氧化物产品中氟含量还未见报道[2 ,3] 。本文研究用低压离子色谱 (ＬＰＩＣ)法测定稀土ＣｅＯ2 中氟含量。试验证明 ,样品预处理时 ,在ＨＣｌＯ4介质中加入ＡｇＣｌＯ4以消除阴离子干扰 ,并用水蒸气将氟蒸馏出 ,以ＫＯＨ溶液吸收。选择 1 .2ｍｍｏｌ/ＬＮａ2 ＣＯ3作淋洗液 ,ＬＰＩＣ测氟。与氟试剂法 (ＧＢ)作比较分析 ,两种方法测定结果一…     

反相高效液相色谱法测定氨噻肟活性硫酯

氨噻肟活性硫酯,又名巯基杂环活性酯、ＡＥ 活性酯,化学名为2 (2 氨基噻唑 4 基) (顺式) 2 甲氧亚胺乙酰硫代苯并噻唑,为淡黄色针状结晶,是制造头孢三嗪、头孢他美和头孢地嗪等头孢类抗生素的重要原料,常采用氨噻肟乙酸在三苯基膦催化下与二硫化二苯并噻唑(ＤＭ)反应合成[1]。目前,氨噻肟活性硫酯的定量分析方法未见报道。本文建立了测定氨噻肟活性硫酯的反相高效液相色谱法,该法灵敏度高,线性范围宽,重现性好,分析速度快,准确。用于实际样品检测,结果令人满意。1　实验部分1.1　仪器与试剂　　ＳｈｉｍａｄｚｕＬＣ 6Ａ高效液相色谱仪,…     

钒（V）—2—（2—噻唑偶氮）—5—二甲氨基苯甲酸显色反应的研究

钒是具有重要用途的元素 ,其测定受到重视。二安替比林甲烷类[1]及杂环偶氮苯酚类显色剂[2 ,3]测定钒灵敏度和选择性较高 ,变色酸偶氮类显色剂[4 6 ]的应用也曾有报道 ,而杂环偶氮苯甲酸类显色剂研究较少[7,8]。本文研究了钒 (Ⅴ )与 2 (2 噻唑偶氮 ) 5 二甲氨基苯甲酸 (ＴＡＭＢ)的显色反应 ,结果表明 ,在 ｐＨ 3 .5 3 .8甲酸 ＮａＯＨ缓冲介质中 ,钒(Ⅴ )与ＴＡＭＢ反应生成一种稳定的可溶于水的蓝色配合物。1　试验部分1.1　仪器与试剂72 1型分光光度计ｐＨＳ 2型酸度计钒 (Ⅴ )标准溶液 :用偏钒酸铵 (ＮＨ4 ＶＯ3)水溶后配成含钒 1…     

La(ClO4)3-BAPOAP-H2O(30 ℃)三元体系的相平衡和Ln2(BAPOAP)3(ClO4)6的合成与表征

安替比林 ( AP)衍生物可用于稀土的分析测定及协同萃取[1] ,安替比林稀土配合物的合成 [2 ] 及其发光性质和磁学性质等 [3,4 ]的研究已有报道 .在对具有芳基侧链的 4- (邻氯苯甲酰基 )氨基安替比林 [5]、4- (对氯苯甲酰基 )氨基安替比林 [6] 及长链桥联的 N ,N -二安替比林 - 1 ,6-己二酰二胺[7,8] 等与稀土盐相互作用进行研究的基础上 ,本文对短链桥联的 N,N -二安替比林乙二酰二胺与镧系高氯酸盐在水溶液中全浓度范围内的相互作用进行了研究 .1　实验部分1 .1　试剂及仪器　L a( Cl O4 ) 3· 8H2 O用 La2 O3( 99.9% )和 1∶ 1高氯…     

用Grignard试剂C6H5MgBr合成苯甲醛

苯甲醛广泛用于医药、农药、染料、香料等行业[1] 。为了寻找产率高、成本低的新合成方法 ,人们进行了广泛的研究[1 7] 。本文用Ｇｒｉｇｎａｒｄ试剂与苯并咪唑盐[8] 合成苯甲醛。合成路线如下 :1　实验部分ＸＴ 2型数字显微熔点仪 (温度计未经校正 ) :ＰＥ 2 40 0ＣＨＮ元素分析仪 ;ＶａｒｉａｎＩＮＯＶＡ 40 0核磁共振仪 ;试剂均为化学纯。参考文献 [9]合成Ｇｒｉｇｎａｒｄ试剂Ｃ6 Ｈ5ＭｇＢｒ,以四氢呋喃作溶剂。1 1　苯并咪唑的合成在 1 0 0ｍｌ圆底烧瓶中加入 1 0 8ｇ(0 1ｍｏｌ)邻苯二胺和 8ｍｌ(0 2ｍｏｌ) 90 %甲酸 ,90℃下…     

3,4-二氫化雜二氮[1,3]萘-酮-[4]Ⅰ.3-(ω)-二烷氨基-烷基)-3,4-二氫化雜二氮[1,3]萘-酮-[4]的合成

隣氨基苯甲酸与N-(β-二乙氨基-乙基)-甲酰胺或N-(δ-二乙氨基-α-甲基-正丁基)甲酰胺缩合,分别形成3-(β-二乙氨基-乙基)3,4-二氢化杂二氮[1,3]萘-酮-[4]与3-(δ-二乙氨基-α-甲基-正丁基)3,4-二氢化杂二氮[1,3]萘-酮-[4]。 5-氯代-隣位氨基苯甲酸舆N-(β-二乙氨基-乙基)-甲酰胺或N-(δ-二乙氨基-α-甲基-正丁基)-甲酰胺缩合,分别形成6-氯代-3-β-二乙氨基-乙基-3,4-二氢化杂二氮[1,3]-萘酮-[4]及6-氯代-3-(δ-二乙氨基-α-甲基-正丁基)-3,4-二氢化杂二氮[1,3]萘酮-[4]。     

4,4‘—二硝基重氮氨基苯的新法合成及其与镉的显色反应研究

4,4′—二硝基重氮氨基本(DNAAB)是一种测定镉、汞等金属离子的优良的三氮烯试剂[1],其合成一般是用H2SO4—NaNO2作重氮化试剂,分重氮化和偶联两步加入反应物合成[2]。但在H2SO4作用下,NaNO2易放出NO2有毒气体。我们摸索出以亚硝酸正丁酯为重氮化试剂,以本方法合成,克服了上面缺点,并且产品纯度高,收率也较文献方法好[3]。研究了其与Cd2 的显色反应,以双峰双波长法测定,摩尔吸光系数达2.52×105L·mol-1·cm-1,用拟定方法测定了人发中镉含量,结果令人满意。1　实验部分1.1　仪器与试剂仪器:752型紫外光栅分光光度计(上海申化仪表自…     

高效液相色谱法测定药物制剂中诺氟沙星

诺氟沙星(Norfloxacin,简称 NFCX)的化学名为 1-乙基-6-氟-1,4-二氢-4-氧代-7-(1-哌嗪基)-3-喹啉羧酸,是一种氟喹诺酮类抗菌药,具有广谱的抗菌作用.鉴于其在医药上的应用价值,NFCX 含量的测定一直为人们所关注.目前该药的测定,中国药典采用非水滴定法[1],其方法操作繁琐,高浓度的乙酸对人体也有害.另外还有紫外分光光度法[2,3]、一阶导数紫外分光光度法[4,5]、火焰原子吸收光谱法[6]、流动注射在线过滤稀释原子吸收光谱法[7]等.也有用高效液相色谱法(HPLC)[8-10]测定,但这些方法多采用反相液相色谱法,使用多相混合流动相,试剂用量大,线性范围小.     

国内光催化研究进展简述

分1975~1985, 1985~1995和1995~2012三个时期简要介绍了国内光催化研究进展, 主要侧重于光催化材料及其改性、应用和反应机理方面的研究进展, 并指出了当前光催化领域存在的一些重要问题和未来的发展趋势, 涉及到光解水、CO₂还原、环境净化和选择性有机合成等方面.     

青蒿素研究进展

青蒿素是目前治疗疟疾的特效药。本文对自青蒿素发现以来的最新研究进展进行了比较详尽的综述。内容包括: 青蒿素的发现及历史, 青蒿素的来源, 青蒿素的全合成,青蒿素的生物合成, 青蒿素衍生物以及植物组织培养生产青蒿素。     

Recent Advances in Analytical Methodology for in vivo Electrochemistry in Mammals

Electrochemistry is one of the most advanced techniques for monitoring neurochemical activities in the living brain because electrochemical approaches bear the advantageous features of high spatial and temporal resolutions, which facilitate its tremendous potential in investigating the highly spatially heterogeneous brain system and the fast dynamics of neurochemical activities. On the other hand, since brain is the most complicated organ in the sense of its numerous kinds of neurochemical species, high selectivity is always required for any analytical methods that approach the brain. In this review, we will discuss various electrochemical methodologies to achieve selective detection of neurochemicals in mammalian brain and the strategies developed mainly by our group towards selective monitoring of both electrochemically active and inactive neurochemicals. At the end, we will discuss possible solutions towards brain mapping of neurochemical species and combination of neurochemical detection strategy with electrophysiology as the direction of future development of electroanalysis in living brain.     

Interpretation of inorganic arsenic metabolism in humans in the light of observations made in vitro and in vivo in the rat

The toxicity of inorganic trivalent arsenic for living organisms is reduced by in vivo methylation of the element. In man, this biotransformation leads to the synthesis of monomethylarsonic (MMA) and dimethylarsinic (DMA) acids, which are efficiently eliminated in urine along with the unchanged form (As_i). In order to document the methylation process in humans, the kinetics of As_i, MMA and DMA elimination were studied in volunteers given a single dose of one of these three arsenicals or repeated doses of As_i. The arsenic methylation efficiency was also assessed in subjects acutely intoxicated with arsenic trioxide (As₂O₃) and in patients with liver diseases. Several observations in humans can be explained by the properties of the enzymic systems involved in the methylation process which we have characterized in vitro and in vivo in rats as follows: (1) production of As_i metabolites is catalyzed by an enzymic system whose activity is highest in liver cytosol; (2) different enzymic activities, using the same methyl group donor (S-adenosylmethionine), lead to the production of mono- and di-methylated derivatives which are excreted in urine as MMA and DMA; (3) dimethylating activity is highly sensitive to inhibition by excess of inorganic arsenic; (4) reduced glutathione concentration in liver moderates the arsenic methylation process through several mechanisms, e.g. stimulation of the first methylation reaction leading to MMA, facilitation of As_i uptake by hepatocytes, stimulation of the biliary excretion of the element, reduction of pentavalent forms before methylation, and protection of a reducing environment in the cells necessary to maintain the activity of the enzymic systems.     

美国化学教育中的科学道德教育

介绍了近年来美国科学界维护科学道德的行动及美国某些大学化学系开设科学道德教育课程的情况     

Electrolysis in nanochannels for in situ reagent generation in confined geometries

In situ generation of reactive species within confined geometries, such as nanopores or nanochannels is of significant interest in overcoming mass transport limitations in chemical reactivity. Solvent electrolysis is a simple process that can readily be coupled to nanochannels for the electrochemical generation of reactive species, such as H(2). Here the production of hydrogen-rich liquid volumes within nanofluidic structures, without bubble nucleation or nanochannel occlusion, is explored both experimentally and by modeling. Devices comprised of multiple horizontal nanochannels intersecting planar working and quasi-reference electrodes were constructed and used to study the effects of confinement and reduced working volume on the electrochemical reduction of H(2)O to H(2) and OH(-). H(2) production in the nanochannel-embedded electrode reactor output was monitored by fluorescence emission of fluorescein, which exhibits a pH-dependent emission intensity. Initially, the fluorescein solution was buffered to pH 6.0 prior to stepping the potential cathodic of E(0)' for the generation of OH(-) and H(2). Because the electrochemical products are obtained in a 2:1 stoichiometry, local measurements of pH during and after the cathodic potential steps can be converted into H(2) production rates. Independent experimental estimates of the local H(2) concentration were then obtained from the spatiotemporal fluorescence behavior and current measurements, and these were compared with finite element simulations accounting for electrolysis and subsequent convection and diffusion within the confined geometry. Local dissolved H(2) concentrations were correlated to partial pressures through Henry's Law and values as large as 8.3 atm were obtained at the most negative potential steps. The downstream availability of electrolytically produced H(2) in nanochannels is evaluated in terms of its possible use as a downstream reducing reagent. The results obtained here indicate that H(2) can easily reach saturation concentrations at modest overpotentials.     

Use of NAA in marine environment and in archaeology in Greece

Neutron activation analysis (NAA) is a very sensitive and accurate multielement analytical method that is widely applied to the investigation of environmental and archaeological problems. The first part of this paper is a review of pollution studies of toxic trace elements in sediments, seawater and marine organisms of Saronikos Gulf, Greece by NAA. The second part of this paper is a review of provenance studies based on minor and trace element research in ancient ceramics, obsidian, flint, limestone, marble and lead by Instrumental NAA, performed at the NCSR Demokritos.     

Styrol in Polystyrol und in Styrol-Methylmethacrylat-Copolymeren

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