原子吸收光谱法测定铅的进展

对近年来国内原子吸收光谱法测定铅的进展进行了评述，内容包括火焰原子吸收光谱法、石墨炉原子吸收光谱法和氢化物发生原子吸收光谱法。     

快速升温石墨炉原子吸收光谱法直接测定水中铅镉银

水中铅、镉和银的含量均为国家生活饮用水卫生标准中的重要指标。对于铅、镉和银的测定,国标法分别用吸光光度法、火焰原子吸收光谱法和石墨炉原子吸收光谱法。石墨炉原子吸收光谱法具有较高的灵敏度,但由于其常规程序升温时间较长,影响了分析速度。     

氢化物发生-原子吸收光谱法测定食盐中微量铅

食盐中铅测定采用萃取-原子吸收光谱法，方法使用有机试剂，操作也复杂。采用石墨炉原子吸收光谱法直接测定，氯化钠干扰很大。本文提出氢化物发生-原子吸收光谱法测定食盐中铅。采用WHG-102A2型流动注射氢化物发生器与原子吸收光谱仪配合，载气压力作为自动化能源，流动注射方     

铅的氢化物原子吸收光谱法研究及地球化学样品中铅的测定

引言氢化物原子吸收光谱法由于具有较高的灵敏度和一些独特的优点而愈来愈受到人们的重视,并在冶金、地质、环保、生化等领域得到了较为广泛地应用。但是由于铅的氢化物生成较困难而且极不稳定,共存元素干扰比较严重又较难消除,因而有关氢化物原子吸收光谱法测定复杂样品中微量铅的报道较少。自1974年Thompson首次报道铅的氢化物原子吸收光谱法以来,不少分析工作者在提高测定铅的灵敏度方面作了大量的工作。采用了加入重铬酸钾、过氧化氢、过硫酸     

微波消解-原子吸收光谱法测定槐花和大黄中微量元素

采用微波消解-火焰原子吸收光谱法和石墨炉原子吸收光谱法测定了中药槐花和大黄中铜、铁、锌、镉、铬和铅。研究了槐花和大黄的微波消解试剂和消解条件。在原子吸收光谱测定的最佳条件下测定槐花和大黄中铜、铁、锌、镉、铬和铅。方法的回收率在89．2％～112．0％之间。     

石墨炉原子吸收光谱法测定尿中铅含量

近年我国铅污染事件呈高发态势,严重威胁群众健康。铅能引起几乎所有器官系统的功能紊乱,尤其是血液和神经系统,尿铅水平是评价体内铅含量的重要指标,石墨炉原子吸收光谱法测定尿铅具有灵敏、快速和准确的特点,本工作在卫生部推荐方法WS/T 18-1996尿铅的石墨炉原子吸收光谱法     

石墨炉原子吸收法测定豆豉中铅和镉

豆豉样品经微波消解后,采用石墨炉原子吸收光谱法快速测定铅、镉。实验优化了石墨炉原子吸收光谱法的测定条件。以磷酸为基体改进剂可提高灰化温度,消除样品中的氯化钠等复杂基体的干扰。该法铅、镉的回收率分别为95.0％、94.6％,精密度（RSD）分别为8.7％和5.1％。结果表明豆豉中铅、镉含量较低。本方法简便、快速、准确,适合于实际的分析工作。     

原子吸收光谱法测定植物叶中微量重金属

用浓硝酸与高氯酸混酸消解植物叶,其中铜、锌及锰含量较高,可直接用火焰原子吸收光谱法测定;铅、镉及铬含量较低,用石墨炉原子吸收光谱法测定;铅和镉含量甚微,受基体及共存元素干扰严重,用标准加入法消除干扰。     

锌粉分离原子吸收光谱测定水中痕量铜、镉和铅

水中痕量铜、镉、铅的测定,一般采用萃取法、加热浓缩法和石墨炉原子吸收法。本法用锌粉作分离试剂,从水中定量析出铜、镉和铅后,用原子吸收光谱测定。本法基于在一定量的氯化锌水溶液中,用锌粉定量析出水中的铜、镉和铅,然后将锌粉溶于稀硝酸中,以原子吸收光谱法测定。该法简单、快速,测定条件要求不严。对水中常见离子进行了试验,没有发现干扰。回收率可达96％以上。检出下限     

火焰原子吸收光谱法测定工业废水中铅锌镉

火焰原子吸收光谱法测定微量铅、锌、镉的报道较多,该法用于工业废水的测定,可实现连续分析,成本低、操作简单,能快速准确地得到测定结果,可及时有效地进行监控。经石灰、片碱处理后的工业废水中含高钠、钙等碱土金属、碱金属等离子,用火焰原子吸收光谱法直接测定此废水中铅、锌、镉的报道不多。     

利用手持技术改进测定乙醇分子结构实验

利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。     

光谱仪测试范围的扩展

由于石化行业的生产需要，其材质的使用具有多样性和广泛性，经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识，根据光谱仪的测试能力及标样的采集，实现了一个或几个元素测量范围的扩展，并对其测量的影响因素进行了研究。     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

物质分配系数的测定实验改进

实验教学目的是从解决实际问题出发,以实验技术训练和实验设计思想培养为目标。介绍了将单一的物质分配系数测定实验改进为综合实验,提高了实验效果及实验资源利用率。     

Calculation of enthalpies of hydrogenation of hydrocarbons

Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。