顶空冷原子吸收间接测定水中微量硫化物

水中硫化物测定是评价水质污染的重要指标,目前检测方法有化学比色法^[1],火焰原子吸收间接法^[2],导数导波极谱法^[3]等。前者操作麻烦,灵敏度低;后者仪器昂贵,操作复杂,本文提出用顶空冷原子吸收法间接测定水中微量硫化物,样品无需任何处理,直接取样检测,操作简便快速,结果准确,对生活饮用水分析的结果满意。     

催化滴定法快速测定磷矿中的微量碘

目前,测定微量碘的主要方法,不外有以下几种:1.碘-淀粉比色法;2.碘-有机试剂比色法;3.催化法。其中催化法灵敏度最高,但催化法往往难于掌握,一般认为易受其他元素干扰,需要繁琐的分离手续。本文拟定了一个不需要分离的快速测定磷矿中微量碘的催化滴定法,并在分解矿样的问题上做了一些工作。碘的催化     

催化动力学紫外光谱法测定农药合成废水中的微量甲醛

正甲醛是有特殊气味的气体,易溶于水,环境水中甲醛的含量较低,但其对人体危害较大。因此,完全有必要实时监测废水中微量甲醛的含量。测定微量甲醛的方法较多,其中催化动力学分光光度法由于其仪器要求简单,在近年得到了较快的发展。这类测定方法通常采用微量甲醛作为催化剂,催化氧化剂氧化有色染料褪色的方法,按被氧化物的种类分为甲基橙法[1-6]、甲基红法[7-10]、亚甲基蓝法[11]、溴甲酚绿法[12-14]、络黑T法[15]、溴酚蓝法[16]、二甲酚橙     

石墨炉原子吸收法间接测定水中碘

石墨炉原子吸收法直接测定金属元素,灵敏度很高,直接测定非金属元素碘则存在困难。本文参考文献[1]提出用石墨炉原子吸收法间接测定水中碘,以代替操作繁锁的催化比色法与气相色谱法[2]。方法原理是通过加入硝酸汞,使之与水中碘生成较难热解离的碘化汞,测定汞含量便可间接求得碘含量。过量的汞可通过干燥灰化阶段预先排除,不干扰碘化汞吸收峰的出现。本法测定碘含量范围为1～10μg·L~(-1),对碘2和10μg·L~(-1)重复测定五次的相对标准偏差分别为6.0％和3.2％。平均回收率分别为95％和96％。检出限为1μg·L~(-1)。1 试验部分1.1 试剂与仪器 去离子水:电阻率达2M·cm以上 过氧化氢:3.0％（10d内有效） 碘化物标准溶液:100μg·ml~(-1),称取干燥器中放置24h的优级纯碘化钾0.1308g,溶于纯水中并定容1L。使用时稀释成0.025μg·ml~(-1)工作液。 硝酸汞溶液:0.4g·L~(-1),称取硝酸汞0.20g溶     

催化褪色光度法测定废水中痕量镉

镉是环境中有严重污染作用的重金属之一,对人体健康危害很大,因而准确有效地测定各种样品中微量镉具有非常重要的意义.目前在镉的测定中,主要有比色法[1]、分光光度法[2,3]、原子吸收光谱法[4]、微分电位溶出法[5]、电感耦合等离子发射光谱法(ICP-AES)[6]等,但采用催化光度法测定镉的报道极少.     

分光光度法测定水体中痕量碘化物

碘是人体必需的微量营养元素之一。碘缺乏可造成地方性甲状腺以及以呆、小、聋、哑、瘫为特征的地方性克丁病;碘化物含量过高时,也可引起高碘甲状腺肿[1]。目前,痕量碘的测定方法主要有分光光度法、色谱法、原子吸收光谱法和差示脉冲极谱法等[2-5],其中分光光度法为推荐方法。分光光度法的基本原理为:在酸性条件下,碘离子对亚砷酸与硫酸铈的氧化还原反应具有催化能力,且此作用与碘离子的量呈非线性比例。在反应一定时间后,加入硫     

5-Br-DMPAP吸光光度法测定奶粉中微量锌

锌是人体中含量最高的微量金属元素。锌的生物功能是多方面的 ,如参与各种酶、核酸和蛋白的合成 ,参与人体免疫功能及维生素A的代谢 ,增强机体抗感染能力等。人体缺锌时 ,会出现生长发育迟缓 ,并诱发多种疾病的产生。因此 ,测定锌的含量在临床上有重要的价值[1] ,建立简便准确测定锌的方法成为分析工作者关注的问题。目前 ,测定食品中微量锌的标准方法为双硫腙比色法和原子吸收光谱法[2 ] ,其特点是灵敏度不高且选择性差。表面活性剂应用于光度法已有很多报道[3～ 6 ] ,本文在 pH 9.0时 ,OP存在下 ,利用掩蔽作用 ,样品不经分离 ,可直接进…     

流动注射化学发光植物组织传感器测定草酸盐

草酸是尿道结石主要成因之一 .统计结果表明 ,90 %以上结石均含草酸钙 .回肠病、口角性肠胃炎及脂肪吸收不良均可引起尿液中草酸的增加 .草酸盐的测定在临床上具有重要意义 .微量草酸测定的传统方法是变色酸比色法或偶氮化合物比色法[1 ] .测定草酸盐的方法还有原子吸收光谱法[2 ] 、高效液相色谱法[3] 、离子色谱法[4] 、光度法[5] 和草酸氧化酶法[6] 等 .这些方法或操作复杂、耗时 ,或灵敏度低 ,使其应用受到限制 .本文提出一种测定草酸盐的新方法 ,其原理为草酸 +Ｏ2草酸氧化酶 ＣＯ2 +Ｈ2 Ｏ2 ,Ｌｕｍｉｎｏｌ+Ｈ2 Ｏ2 ｈｖ　　将含有草…     

硫氰酸钾—乙酸体系示波极谱法测定罐头食品中微量铜

食品卫生检验工作中微量铜的测定方法有二乙氨基二硫代甲酸钠比色法,原子吸收分光光度法,示波极谱法也有报道。根据极谱催化波的研究理论,CNS-离子可造就极谱催化波,提高测试的灵敏度。笔者在前人研究工作的基础上,结合自己的条件,进行了0.06mol·L~(-1)硫氰酸钾-0.15mol·~(-1)乙酸体系示波极谱法测定食品中微量铜,应用于罐头食品中微量铜的测定,只加一次试剂既可完成测定工作,方法具有简便、快速、准确、灵敏、样品用量少、成本低、稳定性好的优点,适合于大批、单个食品,水中微量铜的测定。     

催化光度法测定微量铜

铜是人体内多种酶的活性成分,以人体的新陈代谢有重要调节作用[1]。因此研究铜的分析方法一直引起人们的关注。关于动力学分析法测定Cu(Ⅱ）已有不少文献报道[2-4],但大多是利用铜催化H2O氧化有机染料褪色为指示反应。罗丹明B具有较大的摩尔吸光系数,用于催化动力学分析其测定灵敏度比一般指示剂更高。本研究发现在硫酸介质中Cu( Ⅱ）对溴酸钾氧化罗丹明B的褪色反应有着强烈的催化作用,据此建立了一种新的催化光度测定微量铜离子的反应体系,可用于一些含铜物质的鉴定。     

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。     

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.     

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。     

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。