铋及氧化铋中微量碲的极谱催化波测定

金属铋中碲的含量在ppm级或在其以下,一般采用萃取-比色法测定,或用砷为载体还原沉淀法富集,这些方法对于处理不足微克量的碲并不理想。本文采用巯基棉在较大的酸度范围内把低至0.01μg的碲从铋中分离出来。对于微量碲的测定,极谱催化波具有较高的灵敏度,已报道的催化波体系有很多种,我们选择了0.6mol/L NH_4OH-0.01mol/L EDTA-0.3mol/L 酒石酸钠-5.7×10~(-5)mol/L Pb~(2+)-0.54mol/L Na_2SO_3体系,碲的峰电位为-1.16伏(SCE),该体系可允许一定量的铋存在,必要时还可同时测定试样中痕量硒,应用此法可     

沉淀分离ICP-AES法测定高纯阴极铜中铅铋碲

研究了用虱氧化铁共沉淀分离富集高纯阴极铜中铅、铋和碲的最佳条件与ICP-AES法的最佳工作条件。在选定的最佳条件下测铅、铋和碲的检出限分别为0．0034,0．013和0．0077μg·ml-1,回收率分别为97．8%-100．8%、95．5%-106．5%和98．5-100．5%。测定高纯阴极铜中铅、铋和碲,结果满意。     

火焰原子吸收光谱法测定铋渣中银的含量

<正>铋渣是有色金属冶炼工业生产中的一种中间产品，是回收铋的重要原料^[1-2],其含有多种贵金属以及其他一些有价金属^[3-5]。采用合适的方法快速、准确地测定铋渣中银的含量，对企业工业生产过程具有较为重要的指导意义。目前测定银含量的主要方法有火试金富集重量法^[6-9]、电位滴定法^[10-11]、火焰原子吸收光谱法^[12-17]、电感耦合等离子体原子发射光谱法(ICP-AES)^[18-20]以及电感耦合等离子体质谱法(ICP-MS)^[21-22]等。火试金富集重量法存在灰吹时银损失的问题，对灰吹温度的控制要求较高，且基体铋对测定结果有较大干扰^[23];电位滴定法在滴定溶液标定、滴定终点判定等步骤要求精准；ICP-AES则存在样品光谱干扰较多，对于进样基体浓度水平、酸度的要求苛刻等问题；ICP-MS更多应用于高纯材料痕量杂质元素分析领域。利用火焰原子吸收光谱法具有较好的分析精度、检出限低，以及仪器长期稳定...     

碲化铜中碲含量测定方法的精密度

在有色金属行业标准碲化铜化学分析方法起草过程中,拟定了还原分离–硫酸亚铁铵返滴定法测定碲化铜中碲含量,并组织11家实验室参加了协同实验,得到碲化铜中碲的测定结果。按照GB/T 6379.2–2004标准的规范要求,采用曼德尔k图和h图、格拉布斯检验和柯克伦检验法对数据的一致性和离群值进行检查,计算出该方法精密度试验中重复性限(r)和再现性限(R)的结果。实验证明,统计计算的得到的r和R能反映该方法适用性的真实情况。该方法可以作为有色金属行业标准推广使用。     

碲铋矿中碲铋分离方法的研究及应用

本文对富碲铋矿中碲铋的分离条件进行了详细研究。在ｐＨ８～１２范围内，当Ｆｅ＞１０ｍｇ时，Ｔｅ、Ｂｉ与Ｆｅ共沉淀完全而与其它杂质元素分离，沉淀用１０％ＫＯＨ溶解Ｔｅ而与Ｂｉ、Ｆｅ分离，溶液经酸化后用Ｋ２Ｃｒ２Ｏ７法滴定Ｔｅ。平行测定１０次碲铋矿粉和矿渣，ＲＳＤ为１．０７％。     

盐酸溶样-原子荧光光谱法测定土壤和沉积物中的砷

正目前,测定土壤和沉积物中砷的标准方法有HJ680-2013《土壤和沉积物汞、砷、硒、铋、锑微波消解/原子荧光法》[1]、GB/T 22105.2-2008《土壤质量总汞、总砷、总铅的测定原子荧光法第2部分:土壤中总砷的测定》[2]和NY/T 1121.11-2006《土壤检测第11部分:土壤总砷的测定》[3]等。常用的消解体系主要有盐酸-硝酸(3+1)溶液、硫酸-硝酸-高氯酸混合酸和硝酸-盐酸-高氯酸混合     

火焰原子吸收光谱法测定硒碲混合物中的碲

建立了酒石酸-硝酸-盐酸混酸溶解样品,在王水-酒石酸介质中,采用空气-乙炔火焰在原子吸收光谱仪上测定硒碲混合物中碲的方法。研究了样品处理方法、乙炔流量、燃烧高度、灯电流、溶液介质等有关工作条件。实验表明碲浓度在1～20μg/mL范围内与吸光度呈良好的线性关系,回归方程为A=0.0229C+0.0009,相关系数0.9998,检出限0.08μg/mL。适合于硒碲混合物中碲的测定,相对标准偏差为0.9%～1.3%,回收率为98%～102%。     

氯化银沉淀分离-氢化物发生-原子荧光光谱法测定银锭中硒和碲

硒和碲是银锭中的主要有害杂质元素,依据国家银锭标准[1],硒和碲是必检项目。目前,其测定方法有国家标准方法电感耦合等离子体原子发射光谱法(ICP-AES)[2],而这种仪器成本和运行费用十分昂贵,且检出限较高。近年来,氢化物发生-原子荧     

硫酸分离–火试金重量法测定碲化铜中的金和银

建立了用硫酸分离-火试金重量法测定碲化铜中的金和银含量的方法。用硫酸溶解碲化铜样品,过滤,除去铜和碲,得到含金、银的沉淀物,沉淀物经灰化、配料、高温熔融制得铅扣。将铅扣灰吹,得到金银合粒,用硝酸溶解分离金,用重量法测定金含量。用金银合粒的质量扣除金粒的质量和分金液、洗液中杂质的质量即为银含量。采用灰皿、残渣熔融法补正,或用含碲、铜物料做基体加入纯金、纯银同试样方法测定,根据金、银的回收率加以补正,从而得到试样中的碲含量。实验结果表明,浓硫酸的加入量为30 mL,残余量应不少于15 mL。火试金中硅酸度为1左右,试样进炉温度以900℃为宜。该方法金、银测定结果的相对标准偏差分别为0.33%~1.97%,0.28%~1.27%(n=9)。金的回收率为98.5%~100.2%,银的回收率为95.5%~101.4%。该法满足生产控制检测和贸易结算的要求。     

硒和碲的离子交换分离与诱导测定

硒和碲的还原反应对金的还原有诱导作用。硒或碲的量与金的还原速度有一定的比例关系。这是诱导方法的基础。Lakin等与Hubert均曾用诱导反应测定碲,但未作硒的测定。因不同量硒或碲诱导产生的金溶胶有不同的色调,本文建议用金溶胶作为硒或碲的标准系列。用诱导反应测定硒和碲的主要困难是硒的分离。按太秦康光等的离子交换法,碲的分离没有困难。Yoshino认为在pH0.7—5.0硒定量通过交换柱,并指出在pH3当Fe/Se重量     

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。     

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.     

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.     

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。