沉淀分离——氢化物原子吸收光谱法测定铜粉中微量铋

原子吸收光谱法测定铜粉中微量铋时,大量铜的存在严重干扰铋的测定。本文探索了以氢氧化铁作沉淀剂,经过两次共沉淀的分离步骤,有效地解决了铜的干扰问题。标准试样经分离后用于原子吸收测定,回收率     

吡咯烷二硫代氨基甲酸铵-Ni(Ⅱ)快速共沉淀分离富集和原子吸收光谱法测定痕量铜、铅和镉

研究了用吡咯烷二硫代氨基甲酸铵(APDC)为沉淀剂,以Ni(Ⅱ)为载体离子的共沉淀体系快速共沉淀分离富集铜、铅和镉,并用火焰原子吸收光谱(FAAS)测定的方法。通常情况下,内标元素和载体离子选择不同的元素,本文尝试将Ni既作为载体又作为内标元素。实验证明,该体系在pH=3.0的条件下,能够定量共沉淀试样中的铜、铅和镉。当试液为100 mL时,铜、铅、镉的检出限分别为9.7×10-3、3.3×10-2,1.01×10-3μg.mL-1,加标回收率为95.8%~101.8%,取得了较为满意的结果。本法只需快速收集部分沉淀,与传统的共沉淀方法比较,具有快速、简便、重现性好的优点。     

复杂矿石中锡的碘量法测定

用经典的碘量法测锡具有快速、操作简便的优点,但对某些含干扰元素的复杂矿物必须经过分离才能测定。干扰元素主要有砷、铜、钨、钼、锑、钒、铬、铋、硝酸根及亚硝酸根等。本法利用在EDTA二钠的碱性溶液中铍、锡均可生成不溶性氢氧化物这一特点,将试样以碱熔分解后,以EDTA为掩蔽剂,加入硫酸铍作载体,在氨性介质中使锡和铍共沉淀而与干扰元素钨、钼、钒、铜、砷、锑、铋、铬(Ⅵ)分离;钛、铬(Ⅲ)也与锡、铍一起沉淀,但铬(Ⅲ)以过氧化钠熔矿后已氧化至六价而不干扰,钛量少于24毫克时也不影响测定。     

ICP-AES法测定钨矿中的钨

本文通过一系列的条件试验研究,确定了试样用HCl、HNO3、HF、H3PO4高温溶样,在碱性溶液中,用NaOH溶解钨,并使之与铜等杂质形成沉淀分离,在HCl介质中加入酒石酸,用电感耦合等离子体原子发射光谱法(AES-ICP)测定钨量,方法简便快速,准确可靠,测定范围宽,适用性广,用于钨矿中钨(0.040%~60.00%)的测定。其(n=6)相对标准偏差为(2.70%~0.13%),加标准回收率,钨在(97.80%~99.97%)之间。     

差示分光光度法测量Cu30W70钨铜合金中钨的含量

采用传统的湿化学差示分光光度分析方法,研究了广泛用于军工、高压开关、电火花电极、电子封装的新型材料钨铜合金中钨含量的定量分析方法。由于该材料的耐腐蚀性,试样溶解是关键,实验表明采用盐酸+硝酸(9+1)、硫酸+磷酸(1+3)混合酸低温加热溶解,测定时加入草酸胺掩蔽铜的干扰,用硫氰酸胺显色。以Cu30W70为例用40%的钨为参比,配制一系列标准溶液制作工作曲线,钨含量在5~10μg/mL内服从比耳定律,方法的相对标准偏差(RSD)为1.6%,加标回收率为101.6%,适用于含钨45%以上的钨铜合金中钨的测定。     

差示法测量Cu30W70钨铜合金中钨的含量

研究了广泛用于军工、高压开关、电火花电极、电子封装的新型材料钨铜合金[1]中钨含量的定量分析,采用传统的湿化学差示分析方法。由于该材料的耐腐蚀性,试样溶解是关键,通过实验决定采用9 1盐硝酸和1 3硫磷酸混合酸低温加热溶解。加入草酸胺掩蔽铜的干扰。用硫氰酸胺显色。以Cu30W70为例用40%的钨为参比,配制一系列标准制作工作曲线。钨含量在5～10μg/ml内服从比耳定律。方法的精密度RSD=1.6%,回收率为97.2%～101.4%。适用范围为含钨45%以上的钨铜合金。     

差示分光光度法测定Cu30W70钨铜合金中钨的含量

采用传统的湿化学差示分光光度分析方法,研究了广泛用于军工、高压开关、电火花电极、电子封装的新型材料钨铜合金中钨含量的定量分析方法。由于该材料的耐腐蚀性,试样溶解是关键,实验表明采用盐酸+硝酸(9+1)、硫酸+磷酸(1+3)混合酸低温加热溶解,测定时加入草酸胺掩蔽铜的干扰,用硫氰酸胺显色。以Cu30W70为例用40%的钨为参比,配制一系列标准溶液制作工作曲线,钨含量在5~10μg/mL内服从比耳定律,方法的相对标准偏差(RSD)为1.6%,加标回收率为101.6%,适用于含钨45%以上的钨铜合金中钨的测定。     

共沉淀分离富集-电感耦合等离子体原子发射光谱法测定高纯氧化钨中痕量金属杂质

提出了以Ｌａ（ＯＨ）３为共沉淀剂，对高纯氧化钨中的痕量金属杂质元素经共沉淀预分离富集后进行ＩＣＰ－ＡＥＳ测定的分析方法。探讨了影响杂质元素回收率和钨残留量的若干因素，确定了合适的分离富集条件。合成试样和标准样品的测试结果表明： Ｂｉ、Ｃａ、Ｃｄ、Ｃｏ、Ｃｕ、Ｆｅ、Ｍｇ、Ｍｎ、Ｎｉ、Ｐｂ、Ｓｂ、Ｓｎ、Ｔｉ等元素能被定量分离回收，回收率和精密度均令人满意。     

共沉淀分离富集—电感耦合等离子体原子发射光谱法测定高纯氧化？…

提出了以Ｌａ（ＯＨ）３为共沉淀剂，对高纯氧化钨中的痕量金属杂质元素经共沉淀预分离富集后进行ＩＣＰ－ＡＥＳ测定的分析方法，探讨了影响杂质元素回收率和钨残留量的若干因素，确定了合适的分离富集条件，合成试样和标准样品的测试结果表明，Ｂｉ，Ｃａ，Ｃｄ，Ｃｏ，Ｃｕ，Ｆｅ，Ｍｇ，Ｍｎ，Ｎｉ，Ｐｂ，Ｓｂ，Ｓｎ，Ｔｉ等元素能被定量分离回收，回收率和精密度均令人满意。     

ICP—AES法测定污水中的锌,铜,镍,镉

以氢氧化镧为共沉淀剂,对污水中锌、铜、镍、镉进行共沉淀分离富集后,用ＩＣＰ－ＡＥＳ法进行测定。在２５０ｍＬ污水中加入４．０ｍＬ镧溶液及３．０ｍＬ ＮａＯＨ溶液,使四种元素定量分离回收。测试结果表明,各元素的回收率在９８％～１０６％之间。     

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。     

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。     

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.     

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。