喷流型发生器、氢化物-原子吸收光谱法测定岩石、矿物中的铅

本文采用喷流型连续氢化物发生器,氢化物-火焰原子吸收光谱法对岩石、矿物中微量铅的测定条件进行了研究。用铁氰化钾作为铅的氧化剂,草酸为干扰抑制剂,于217.0nm波长,测得铅的特征浓度为0.012μg/ml(1％吸收)。相对标准偏差(对0.6μg/ml Pb)为0.97％。     

反相离子对色谱法同时测定钼和铼的研究

近年来高效液相色谱法(HPLC)巳广泛应用于分离和测定各种金属离子与有机试剂的络合体系。本文以Tiron作为络合剂,用反相离子对色谱法,在紫外光谱区(254nm)同时测定钼和铼。结果表明,在进样量为20μl,钼的浓度范围在10.0—80.0μg/ml而铼在20.0—80.0μg/ml呈线性。变异系数(n=15)对于0.80μg的铼为1.42％,对于0.40μg的钼为1.86％。实验部分 1.仪器装置:WATERS,510型高压泵;730型数据处理机;441型UV/Vis检测器;     

卡尔曼滤波析相光度法同时测定锰铁铜锌镉的研究——5-Br-PADAP—Triton X-100体系

运用卡尔曼滤波递推法,以2-(5-溴-2-吡啶偶氮)—5-二乙氨基苯酚(5-Br-PADAP)为显色剂,建立了同时测定锰、铁、铜、锌、镉析相光度法.在pH9.0硼酸-氢氧化钠介质中,胶束溶液在95℃加热1h,配合物被Triton X-100相完全富集,最大吸收峰分别为锰566nm、铁556nm、铜560nm、锌562nm、镉557nm,工作曲线范围除镉为0～8μg/5ml外,其余均为0～10μg/5ml.应用于大米中锰铁铜锌镉的同时测定,结果满意.     

原子捕集—火焰原子吸收法测定工业废水中痕量镉

1 引言 原子捕集是在火焰原子吸收测量中浓缩待测原子的一种预富集手段。以往的报道原子捕集管多用石英材料,选用不锈钢材料作捕集管测镉的方法尚未见报道。本文系统研究了使用不锈钢管作捕集管,各种因素对镉捕集与释放的影响,选择了最佳工作条件。捕集3min测镉的特征浓度为1.52×10~(-4)μg/ml/1％,灵敏度比常规法提高了116倍。相对标准偏差为1.5％。而且不锈钢管具有坚固耐用的优点。本法用于工业废水中痕量镉的测定,获得满意结果。     

金属的高灵敏光度法之研究——Ⅰ.锰(Ⅱ)——铬黑T体系

我们注意到:在pH=9.3-10.0的氨性介质中,锰(Ⅱ)在加热条件下会使兰色的铬黑T很快地转变成黄色的产物。在试剂空白的最大吸收峰λ=611nm处,以加入不同量锰(Ⅱ)的试样为参比,来测定试剂空白的吸光度,在0-0.25μg Mn (Ⅱ)/25ml的范围内遵从Beer定律,其Sandell灵敏度达1.07×10(-5)μg/cm~2,是高锰酸钾法的2500余倍,成为目前测定锰灵敏度最高的光度法。 (一)仪器及主要试剂 721型及751型分光光度计。铬黑T,0.1％水溶液。蒸馏水,须陈放数日。锰标准液,把含锰(Ⅱ)1mg/lml的标准液稀释至0.05μg/ml。 (二)实验方法取0.2μg锰(Ⅱ)于25ml容量瓶中,依次加入4.0ml铬黑T溶液,3.0ml NH_4Cl-NH_4OH     

感耦等离子体发射光谱法测定高纯氧化钇中的痕量稀土元素

本文采用国产WPG-100型一米光栅摄谱仪、GP3.5-D1型高频等离子体发生器、气动雾化器,以不去溶方式进样直接测定纯度为99.995%的氧化钇中十四个稀土杂质元素。其中除镨(17μg/g)和钸(7μg/g)外,测定下限均为0.3-3μg/g(以氧化物计)。当被测元素的含量为3-17μg/g时,相对标准偏差为2.3-7.3%(钸和镨除外)。样品用盐酸溶解,酸度和共存元素的影响很小,方法简便、快速。     

导数分光光度法同时测定叶绿素a和叶绿素b

1 引言 本文采用一阶导数分光光度法同时测定叶绿素(Chl)a和b,检测下限分别为14.3ng/ml和37.8ng/ml,测定范围分别为0.5～20μg/ml和0.5～10μg/ml,相对标准偏差分别为1.01%和1.44％。 2 方法要点 取适量Chl a或Chl b的90％丙酮溶液,在美国Beckman DU-7HS型分光光度计上以600nm/min的扫描速度绘制吸收光谱,并转换成一阶导数谱图(△λ=4)。由该谱图可知,Chl b在467.0nm处有一个导数     

氧屏蔽空气—乙炔焰原子吸收法测定玻璃中氧化钡

我们试验出火焰发射法测玻璃中氧化钡之后,又发现另一种氧屏蔽空气-乙炔原子吸收法,效果更佳。氧屏蔽空气-乙炔焰作为新的高温火焰出现后,能测一些普通原子吸收法所不能测的元素,试验证明在相同仪器条件下,该火焰中氧化钡灵敏度提高到2.9μg/ml,比普通火焰提高12.6倍。如加大乙炔流量其灵敏度还可以提高。此时氧化钙干扰就相应地大幅减小,(1.5mgCaO/ml液吸光度为0.019)。 (一)仪器及其工作条件: 使用WFX-110型原子吸收分光光度计(附PZ58-1型数子电压表),燃烧器按王升章等资料制造,     

简便吸收光谱法测定饮料中共存色素诱惑红和柠檬黄

建立了同时测定饮料中共存色素诱惑红和柠檬黄的简便吸收光谱法。在pH 7.2～8.7 Tris-HCl介质中,诱惑红和柠檬黄与双绿SF反应生成离子缔合物。诱惑红-双绿SF在可见光区有正吸收峰(496 nm)和负吸收峰(570 nm),诱惑红的质量浓度在0.03～12.4 mg/L范围内服从朗伯-比尔定律,表观摩尔吸光系数为1.79×104L/(mol·cm)(496 nm)和2.43×104L/(mol·cm)(570 nm),检出限为29μg/L (496 nm)和27μg/L(570 nm),定量限分别为0.78 mg/kg和0.73 mg/kg。柠檬黄-双绿SF在422 nm和660 nm处分别产生1个较强的正吸收峰,柠檬黄的质量浓度在0.04～13.4 mg/L范围内服从朗伯-比尔定律,表观摩尔吸光系数为2.13×104L/(mol·cm)(422 nm)和1.59×104L/(mol·cm)(660 nm),检出限为32μg/L(422 nm)和35μg/L(660 nm),定量限分别为0.87 mg/kg和0.95 mg/kg。当用双波长法测定时,表观摩尔吸光系(κ)为4.22×104L/(mol·cm)(诱惑红体系)和3.72×104L/(mol·cm)(柠檬黄体系),诱惑红体系的检出限和定量限分别为0.014 mg/L和0.38 mg/kg,加标回收率和相对标准偏差分别为98.0%～102%和2.3%～2.8%;柠檬黄体系的检出限和定量限分别为0.017 mg/L和0.46 mg/kg,加标回收率和相对标准偏差分别为97.5%～103%和1.1%～2.2%。该法适于饮料中诱惑红和柠檬黄的测定。     

火焰原子吸收光谱法测定辉锑矿中锑

对辉锑矿中Sb的溶矿条件进行了研究。采用HNO3和酒石酸溶矿,在稀HNO3介质中制备成含Sb的溶液,不经任何分离,用FAAS直接测定Sb含量。线性范围为0～80μg/mL,可用于高含量Sb的测定。1　实验部分1.1　仪器及工作参数岛津680型原子吸收分光光度计;Sb空心阴极灯,波长217.6nm;灯电流8mA;狭缝0.2nm;空气流量80L/min;乙炔流量1.8L/min;燃烧器高度0.7cm。1.2　试剂及溶液酒石酸溶液:20g/L、200g/L;Sb标准溶液:称取高纯Sb2O30.1198g于100mL烧杯中,加入10mLHNO3,10mL200g/L酒石酸溶液,加热溶解,移入100mL容量瓶中,用20g/L酒石酸溶液稀释…     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.