氢化物-氧屏蔽空气乙炔火焰原子吸收法测定锗分析条件的研究

在原子吸收分析中,由于利用氢化物生成反应,大大提高了砷、锑、铋、碲、锡、铅、锗以及硒八个元素的测定灵敏度,国外使用氩氢焰和一氧化二氮-乙炔焰,进行锗的氢化物原子吸收法测定。在此基础上,我们采用磷酸钠为增感剂,结合氧屏蔽原子化方式对锗作了测定。实验部分 1.仪器:WFX-1A型原子吸收分光光度计;AHG-1型半自动氢化物装置。 2.试剂;锗(Ⅳ)标准溶液,10微克/毫升。硼氢化钾溶液5％(含氢氧化钾1.5％),用玻璃过滤漏斗抽滤。磷酸钠20％水溶液。     

高温钴基合金中硒碲铋的分析方法研究

提高反应酸度，降低还原剂浓度，有利于克服基体钴的干扰，在６ｍｏｌ／Ｌ盐酸溶液中，以０．１％ＫＢＨ４作还原剂，１ｇ／ＬＣＯ＾２＋以硒，碲和铋的氢化物产生都没有干扰。利用石墨炉原位富集氢化物，可以直接测定高温钴基合金中硒，碲和铋。     

氢化物发生-原子荧光光谱法同时测定铜精矿中硒和碲的含量

样品0.500 0~1.000 0g与活性炭0.15g和捕集剂氧化镁-氧化锌-碳酸钠(质量比为1∶2∶3)的混合物3g充分混匀,并于750℃焙烧1h,使样品中硒和碲分别生成各自的钠盐。加水50mL和几滴乙醇浓缩至25mL,定容至50mL。分取溶液10.00mL,加入3.6mol·L-1盐酸溶液7mL,加入掩蔽剂20g·L-1三氯化铁溶液1mL掩蔽干扰元素,于沸水浴中保持40min,冷却,定容至25mL作为测试溶液,用氢化物发生-原子荧光光谱法测定其中硒和碲的含量。硒和碲的质量浓度均在100μg·L-1以内与荧光强度呈线性关系,检出限(3s)分别为0.037,0.025mg·kg-1。按此方法测定了两种国家标准物质(GBW 07166和GBW 07234)中硒和碲的含量,标准值和认定值相符。     

氢化物负压发生,夹带氧气的真空无火焰原子吸收测量技术测定砷、锑、硒和锡

在负压氢化物发生器中用1％NaBH_4将砷、锑、硒和锡还原成氢化物后,加入一定量氧气,用真空泵将氧与氢化物的混合物吸入到电热石英管中,同时用原子吸收仪器测定。加入的氧与来自硼氢化钠分解产生的氢反应,生成气态水分子,因而消除了氢对测量元素的干扰。     

氢化物发生-原子荧光光谱法(HG-AFS)测定特硬铅合金中硒和碲

建立了氢化物发生-原子荧光光谱法(HG-AFS)测定特硬铅合金中硒和碲的分析方法。试样经硝酸和酒石酸溶解,硫酸沉淀分离基体铅元素。移取部分试液,在40%盐酸介质中直接用氢化物发生-原子荧光光谱法(HG-AFS)测定样品中的硒;另移取部分试液,加入氢溴酸挥发除去砷、锑、锡、硒等元素,在40%盐酸介质中用氢化物发生-原子荧光光谱法(HG-AFS)测定样品中的碲。考察了测定的最佳条件、铅及共存元素对测定的影响。测定硒和碲的相对标准偏差分别为7.5%～9.3%和3.6%～13.0%,加标回收率分别为88%～92%和98%～102%。准确度和精密度均能满足分析需要,具有较强的实用性。     

氢化物发生-高频电感耦合等离子体发射光谱分析

一、前言氢化物发生-高频电感耦合等离子体(HY-ICP)发射光谱分析是在氢化物发生-原子吸收光谱分析(HY-AAS)的基础上发展起来的。它是使待测元素生成挥发的共价氢化物,然后将生成的氢化物引入ICP,测量其发射光谱。目前已有十种元素可以利用氢化物发生的方法进行测定,它们是砷、锑、硒、碲、铋、锗、锡、铅、铟和铊。这些元素在实际样品中的含量一般并不高,但起的作用却很大。例如上述一些痕量元素能影响钢的冶金性质。由于其中一些元素具有毒性或致癌作用,必须严格控制它们在     

氢化物负压发生器—真空无火焰原子化器的原子吸收光谱法测定碲

在负压发生器中用1％NaBH_4将Te(Ⅳ)还原成碲化氢后,再加入2mL氧气,用真空泵将氧与碲化氢的混合物吸进电热真空石英管中,同时测定原子吸收光谱。加入的氧与硼氢化钠分解产生的氢反应生成水分子,消除了氢对碲的干扰。     

微波消解试样-原子荧光光谱法测定土壤中硒碲

应用HG-AFS法及微波加热试样消解法测定了土壤中硒和碲的含量,对试样消解参数、仪器工作条件及氢化物发生反应条件等作了试验并讨论.该方法测定硒及碲的检出限均为0.01μg·g-1,荧光强度与硒及碲的质量浓度在5～100μg·L-1及0.5～10μg·L-1范围内呈线性关系.应用此方法分析了3个土壤试样,测定值的相对标准偏差(n=6)均小于5%.用标准加入法作了回收试验,硒的回收率在92.0%～102.6%之间,碲的回收率在90.1%～98.8%之间.     

氢化物发生-原子荧光光谱法测定大蒜中砷和硒

采用氢化物发生-原子荧光光谱法测定大蒜中砷和硒。样品经硝酸和高氯酸消解,在盐酸(5+95)溶液中,加入溶于50g·L~(-1)氢氧化钠溶液的20g·L~(-1)硼氢化钾溶液,使其与溶液中砷及硒离子反应生成氢化物。分析中采用载气流量依次为800mL·min~(-1),600mL·min~(-1),屏蔽气的流量均为1000mL·min~(-1)。试样溶液中加入硫脲-抗坏血酸混合溶液作为还原剂。于仪器中引入试样溶液0.5mL,按选定的工作条件操作。砷及硒的质量浓度分别在0.04～0.40,1.00～10.0μg·L~(-1)范围内与其荧光强度呈线性关系,方法的检出限(3s/k)砷为0.017μg·L~(-1),硒为0.314μg·L~(-1)。分别加入两元素的标准溶液作回收试验,测得砷和硒的回收率分别在95.3%～104.4%和94.7%～105.2%之间。     

氢化物发生-荧光光度法测定微量硒

本文提出了一个氢化物发生-荧光光度法测定微量硒的新方法。用硼氢化钾溶液将硒(Ⅵ)还原成H_2Se挥发出来,用8-羟基喹啉-5-磺酸钯溶液吸收,生成难溶的PdSe,释放出的8-羟基喳啉-5-磺酸与Al~(3+)生成发荧光的络合物,其荧光强度与硒(Ⅳ)量成正比。方法的检出限为0.26ng/ml。     

Furyl- and thienyl-silatranes and germatranes

We review our research on the synthesis and study of the physical and biological properties of furyl- and thienylgermatranes and -silatranes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 725–732, June, 1992.     

Review and patents and literature

The use of the insect cell/baculovirus expression system for producing recombinant proteins of bacterial, plant, insect, and mammalian origin has become widespread. The popularity of this eukaryotic expression system is due to many factors, including (1) potentially high protein expression levels, (2) ease and speed of genetic engineering, (3) ability to accommodate large DNA inserts, (4) protein processing similar to higher eukaryotic cells (e.g., mammalian cells), and (5) ease of insect cell growth (e.g., suspension growth). The following review of the literature discusses two engineering aspects of recombinant protein synthesis by insect cell cultures: bioreactor scale-up and insect cell line selection. Following this review patent abstracts and additional literature pertaining to expression of recombinant proteins in insect cell culture are listed.     

Ground- and excited-state aromaticity and antiaromaticity in benzene and cyclobutadiene

The aromaticity and antiaromaticity of the ground state (S 0), lowest triplet state (T 1), and first singlet excited state (S 1) of benzene, and the ground states (S 0), lowest triplet states (T 1), and the first and second singlet excited states (S 1 and S 2) of square and rectangular cyclobutadiene are assessed using various magnetic criteria including nucleus-independent chemical shifts (NICS), proton shieldings, and magnetic susceptibilities calculated using complete-active-space self-consistent field (CASSCF) wave functions constructed from gauge-including atomic orbitals (GIAOs). These magnetic criteria strongly suggest that, in contrast to the well-known aromaticity of the S 0 state of benzene, the T 1 and S 1 states of this molecule are antiaromatic. In square cyclobutadiene, which is shown to be considerably more antiaromatic than rectangular cyclobutadiene, the magnetic properties of the T 1 and S 1 states allow these to be classified as aromatic. According to the computed magnetic criteria, the T 1 state of rectangular cyclobutadiene is still aromatic, but the S 1 state is antiaromatic, just as the S 2 state of square cyclobutadiene; the S 2 state of rectangular cyclobutadiene is nonaromatic. The results demonstrate that the well-known "triplet aromaticity" of cyclic conjugated hydrocarbons represents a particular case of a broader concept of excited-state aromaticity and antiaromaticity. It is shown that while electronic excitation may lead to increased nuclear shieldings in certain low-lying electronic states, in general its main effect can be expected to be nuclear deshielding, which can be substantial for heavier nuclei.     

多环芳二酐型聚酯亚胺膜的透气性能

多环芳二酐型聚酯亚胺膜的透气性能李悦生，丁孟贤，徐纪平（浙江大学高分子科学与工程研究所，杭州，３１００２７）（中国科学院长春应用化学研究所）关键词聚醚酰亚胺，聚酯酰亚胺，膜，透气性通常的聚酰亚胺加工性能较差，在芳环二酐的苯环间引入醚键等柔性基团后，其...     

Determination and study on residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil

A QuEChERS (quick, easy, cheap, effective, rugged, and safe) method for the determination of benazolin-ethyl and quizalofop-p-ethyl in rape and soil by high-performance liquid chromatography-tandem mass spectrometry has been developed in this study. The residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil were determined with the developed method. The half-lives of benazolin-ethyl in rape straw and soil were 3.7–5.1 days and 14.3–26.3 days, respectively. The half-lives of quizalofop-p-ethyl in rape straw and soil were 5.0-6.1 days and 0.3–9.7 days, respectively. The residue of benazolin-ethyl and quizalofop-p-ethyl in rapeseed and soil were below the detection limit (i.e., 0.5?mg?kg^?1, the maximum residue level of European Union for quizalofop-p-ethyl).     

Syntheses and structures of P-anilino-P-chalcogeno- and P-anilino-P-iminodiazasilaphosphetidines and their group 12 and 13 metal compounds

The P-anilino-P-chalcogeno(imino)diazasilaphosphetidines [Me(2)Si(mu-N(t)Bu)(2)P=E(NHPh)] (E = O (3), S (4), Se (5), N-p-tolyl (6)) were synthesized by oxidizing the P-anilinodiazasilaphosphetidine [Me(2)Si(N(t)Bu)(2)P(NHPh)] (2) with cumene hydroperoxide, sulfur, selenium, and p-tolyl azide, respectively. The lithium salt of 4 reacted with thallium monochloride to produce ([Me(2)Si(mu-N(t)Bu)(2)P=S(NPh)-kappaN-kappaS]Tl)(7), which features a two-coordinate thallium atom. Treatment of 4-6 with AlMe(3) gave the monoligand dimethylaluminum complexes ([Me(2)Si(mu-N(t)Bu)(2)P=E(NPh)-kappaN-kappaE]AlMe(2)) (E = S (8), Se (9), N-p-tolyl (10)), respectively. In these complexes the aluminum atom is tetrahedrally coordinated by one chelating ligand and two methyl groups, as a single-crystal X-ray analysis of 8 showed. A 2 equiv amount of 4-6 reacted with diethylzinc to produce the homoleptic diligand complexes ([Me(2)Si(mu-N(t)Bu)(2)P=E(NPh)-kappaN-kappaE](2)Zn)(E = S (11), Se (12), N-p-tolyl (13)). A crystal-structure analysis of 11 revealed a linear tetraspirocycle with a tetrahedrally coordinated, central zinc atom.