双波长双指示剂催化动力学光度法测定茶叶和水中微量锰北大核心CSCD

锰是人体必需的微量元素,人体缺锰会引起许多疾病,如早期胚胎发育不良,成人会引起高血压、肝炎、肝癌和衰老等病状,但锰过量也会引起中毒[1],因此研究食品、保健食品中痕量锰的测定具有重要的现实意义。目前,测定锰的催化动力学光度法已有许多报道[2-6],但大多采用单一指示剂在单波长下进行测定,灵敏度不够高,利用双波长双指示剂体系测定微量组分可提高灵敏度[7],     

双波长双指示剂催化动力学光度法测定茶叶和水中微量锰

<正>锰是人体必需的微量元素,人体缺锰会引起许多疾病,如早期胚胎发育不良,成人会引起高血压、肝炎、肝癌和衰老等病状,但锰过量也会引起中毒[1],因此研究食品、保健食品中痕量锰的测定具有重要的现实意义。目前,测定锰的催化动力学光度法已有许多报道[2-6],但大多采用单一指示剂在单波长下进行测定,灵敏度不够高,利用双波长双指示剂体系测定微量组分可提高灵敏度[7],但这种方法研     

微乳液增敏测定微量锰

锰是人体必需的微量元素,它能促进人体的发育且具有抗癌作用[1]。缺锰会引起动脉硬化和癌症,过量锰会引起锰中毒,使中枢神经系统损害,直至语言障碍,因此,研究和建立高灵敏度的分析测定微量锰的方法具有重要意义。微乳液是由表面活性剂、助表面活性剂和水按适当比例组成的均匀的、透明的、各向同性的热力学稳定体系,与胶束体系比较,具有超低的介面张力和很高的增溶能力,在吸光光度法中日益得到应用[2-5]。本文研究了多种胶束及微乳液对水杨基荧光酮光度法测定锰的增敏作用。结果表明,CTMAB/正丁醇/正庚烷/水微乳液增敏作用最强,并测定了水…     

氧化褪色光度法测定锰

锰是人体需要的一种微量元素,它能促进人体的正常发育,且具有抗癌作用[1]。因此粮食中锰的测定是一个重要的检测项目。目前利用锰(Ⅶ)氧化某些试剂褪色而进行测定锰的方法已有报道[2～5],但高锰酸氧化N,N′ 二(2 羟基 5 磺基苯基) C 氰基甲月替二钠盐(简写作DSPCF)并使其褪色的光度法未见报道。本法用于粮食中微量锰的测定,简便、快速、干扰少,结果满意。1　试验部分1.1　主要试剂与仪器锰(Ⅶ)标准溶液:按常规方法配制0.02mol·L-1KMnO4溶液,用草酸钠作基准标定其准确浓度。使用时稀释成10μg·ml-1锰(Ⅶ)工作液。锰(II)标准溶液:…     

高锰酸氧化茜素红褪色吸光光度法测定中成药中锰

关于锰的测定方法很多,应用最广泛的是高锰酸盐光度法,但此法灵敏度较低.近几年来利用氧化褪色,催化氧化褪色测定锰研究较多.在酸性介质中,高锰酸也能氧化茜素红,根据褪色前后吸光度差可测定微量锰.据此建立了高锰酸氧化茜素红褪色吸收光度法测定锰的方法.应用于中药金银花、厚朴中微量锰测定,结果满意.     

碘化物—碘—孔雀绿—苯体系吸光光度法测定微量锰

基于Mn(Ⅶ)氧化I~-产生I_3~-,I_3~-与孔雀绿阳离子发生离子缔合反应,缔合物可被苯萃取,发展了一种间接萃取吸光光度法测定微量锰的新方法,方法的灵敏度高,摩尔吸光系数达2.51×10~5,是目前光度法测定锰最灵敏的方法之一,且重现性好,具有一定的选择性,用于水样中微量锰的测定,结果满意。     

催化光度法测定粉煤灰中微量锰

粉煤灰作为电厂排放的废物在农业方面有广泛的应用。据文献 [1]介绍 ,粉煤灰中含有一些微量元素 (如锰 )对作物生长有利 ,但其含量如超过临界值会导致作物死亡 ,必须对其准确测定。目前锰光度法测定中 ,催化光度法测定锰已有报道[2～ 4 ] 。本文研究在ｐＨ 9.2 5的氨 氯化铵缓冲溶液中 ,利用痕量Ｍｎ(Ⅱ )催化Ｈ2 Ｏ2 氧化水杨醛肟 (ＳＡＯ)的显色反应测定锰。本法具有较高选择性和灵敏度 ,且操作较简便 ,可准确地测定粉煤灰样品中的微量锰。1　试验部分1.1　主要试剂与仪器Ｍｎ(Ⅱ )标准储备液 :1.0ｇ·Ｌ- 1,用时稀至 0 5 μｇ·ｍｌ- 1…     

PAN共沉淀富集原子吸收测定饮水和人发中的微量锰

使用PAN-Ni(Ⅱ)共沉淀体系分离富集、微量流向进样火焰原子吸收光谱测定饮水和人发中的微量锰。样品中的共存元素不干扰测定，锰的标准加入回收率90%-108%之间。12次重复测定锰含量为0.15μg/mL的试样溶液的变异系数为4.6%,本法简便快捷,取得了较满意的结果.     

吸光光度法测定痕量锰

锰是人体及动物的必需元素[1 ] ,摄入超量会引起毒性 ,所以微量锰测定方法的探讨 ,在水质、食品等方面的测定中具有一定的实际意义[2 ,3] 。锰对于H2 O2 与邻氨基酚的氧化反应具有较好的催化作用。本文研究了在 p H 5.5的 HOAc- Na OAc介质中 ,以邻氨基酚氯仿为萃取剂 ,通过固定萃取时间 ,控制反应进行的程度 ,确定了最佳条件。用于水、食品及人发中痕量锰的测定 ,结果满意。1　试验部分1 .1　仪器与试剂GBC- UV( VIS) 91 6型紫外 -可见分光光度计Mn( )标准溶液 :用 Mn SO4· H2 O配制成1 .0 0 g·L- 1 储备液。过氧化氢溶液 :3…     

催化动力学光度法测定水中微量锰

１引言研究了锰（Ⅱ）催化亮绿ＳＦ褪色反应的动力学特性。在ＮａＡｃ－ＨＡｃ介质中，锰（Ⅱ）对高碘酸钾氧化该试剂的褪色反应具有强烈催化作用，其褪色反应速率与锰（Ⅱ）的浓度在一定范围内呈良好的线性关系。详细研究了亮绿ＳＦ催化动力学光度法测定微量锰（Ⅱ）的条件，建立了测定微量锰（Ⅱ）的新方法。有关文献中催化动力学光度法测定锰（Ⅱ）的检出限大多为１０－１０ｇ／ｍＬ，本方法的检出限为６．０×１０－１１ｇ／ｍＬ，选择性较好，方法相对标准偏差２．５％，用于测定水样中的锰，结果满意。２实验部分２．１主要试剂和仪器…     

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.     

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.     

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。