焦炭标准物质测量不确定度的评定

以国家一级焦炭标准物质(GBW 11106h)为例，对焦炭标准物质的测量不确定度进行评定。分析了不确定度的主要来源，对各不确定度分量进行了评定。焦炭标准物质的全硫、灰分、挥发分、磷含量的扩展不确定度分别为0．02％、0．17％、0．05％、0．001％，热值的扩展不确定度为0．14MJ／kg。     

ICP-AES测定土壤勘查地球化学样品中钼的不确定度评定

采用电感耦合等离子体发射光谱法对土壤勘查地球化学样品中的钼进行测定,并对测量结果进行不确定度评定. 分析了影响测量不确定度的主要来源,对测定全过程的重复性、样品称量、拟合曲线、标准溶液、玻璃量具及仪器等影响不确定度的因素进行分析,按JJF l059—1999《测量不确定度评定与表示》的规定进行评定,并计算出扩展不确定度,使结果的表达更加客观和真实.     

分光光度法测定物质含量的不确定度快速评定

对分光光度法测定物质含量的不确定度的主要来源进行分析并进行不确定度的评定,从而可以对利用分光光度法测定某一具体物质含量的不确定度评定有示范作用。以硅钼蓝光度法测定试样中二氧化硅含量为例说明整个评定过程,取包含因子k=2,则相对扩展不确定度Urel=0.011,扩展不确定度U=kuc=0.07。     

原子荧光法测定水中砷的不确定度评定

评定原子荧光法测定水中砷的不确定度.结合原子荧光法原理和相关实验流程,根据JJF 1059.1—2012《测量不确定度评定与表示》建立原子荧光法测定水中砷的不确定度测量模型,对整个测定过程中的不确定度来源进行分析.测量不确定度的主要来源包括:取样体积、样品定容体积、由标准曲线上查得砷浓度、样品稀释、重复性测定,分别进行...     

X射线荧光光谱法测定铝合金中铜元素的测量不确定度评定

利用X射线荧光光谱法(XRF)对硬铝合金中铜元素进行测定,分析了测量不确定度来源,并对不确定度分量进行评定,经计算得出合成标准不确定度和扩展不确定度。当硬铝合金中铜的质量分数为4.33%时,扩展不确定度为0.17%(k=2)。     

离子色谱法测定PM_(2.5)中可溶性阴离子含量不确定度评议

准确测定大气颗粒物中水溶性组分对分析污染物来源及身体健康具有重要意义。本文采用离子色谱法测定PM2.5中水溶性阴离子(氯离子、硝酸根离子、硫酸根离子)含量,并对测定的不确定度进行分析。分析过程不确定度来源是样品重复性测量引入不确定度,样品测量准确性引入不确定度和标准曲线的不确定度。应用不确定度评定理论,分别计算氯离子、硝酸根离子和硫酸根离子的合成不确定度。结果表明,滤膜质量与取样环节是不确定度的主要来源。为了提高分析准确性,建议使用本底低的滤膜,取全样分析。     

总悬浮颗粒物测试仪检定结果的不确定度评定

对总悬浮颗粒物测试仪检定结果的不确定度进行了评定,分析了检定过程中不确定度的主要来源,如计量标准、测量重复性、检定装置示值误差等.对各不确定度分量进行了量化,求得检定结果的相对扩展不确定度为1.8%(k=2).对检定结果不确定度评定的合理性进行了验证.     

超高效液相色谱法测定化妆品中孕激素的不确定度

采用分层建模方法建立了超高效液相色谱法测定化妆品中黄体酮结果不确定度评定的数学模型,对测量过程中的不确定度来源进行逐层分析和合成,运用最小二乘法对外标曲线拟合的不确定度进行了评定.超高效液相色谱法测定化妆品中孕激素含量的相对合成标准不确定度为0.022,相对扩展不确定度为0.044.该评定对采用外标法定量的高效液相色谱、气相色谱等测定结果的不确定度评定具有参考作用.     

高效液相色谱法测定车内非金属材料中甲醛含量的不确定度评估

依据测量不确定度评定与表示的方法,建立了高效液相色谱法测定车内非金属材料中甲醛含量的测量不确定度评定的数学模型,并对测试过程中各个不确定度分量的来源进行了分析和合成.结果表明,标准曲线的拟合和试验重复性对结果有较大影响.通过规范标准溶液配制的操作,降低测量结果的不确定度,有利于提高检测的准确性和一致性.     

ICP-AES测定糖果中铅质量分数的不确定度评定

建立了电感耦合等离子体发射光谱(ICP-AES)测定糖果中铅的相应数学模型, 对数学模型中各个参数进行不确定度来源分析, 分别对A类不确定度或B类不确定度进行评定. 对各不确定度分量合成和扩展, 得到铅质量分数的不确定度. 结果表明: 标准溶液的配制、标准曲线拟合线性方程及样品溶液的定容是不确定度的主要来源.     

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。     

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.     

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。     

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。     

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.     

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.     

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.