ICP-MS测定铅作业工人血铅含量

建立血中铅含量的测定方法.采用ICP-MS测定铅作业工人血中铅的含量.结果表明所建方法灵敏、精确、快速、线性范围宽,可用于血中铅的含量测定.铅作业工人血铅含量与血锌原卟啉含量有相关性(P0.05),为血铅含量的测定及职业铅中毒的安全防控提供实验数据.     

微分电位溶出伏安法同时测定甘草中痕量铅和镉

建立了在NH4OAc HOAc介质中,用微分电位溶出伏安法测定中药甘草中痕量铅和镉的方法,利用该法对中药甘草煎煮前后及其煎液中铅和镉的含量进行测定。试验表明,镉和铅分别在-0.66V(vs.SCE)和-0.47V(vs.SCE)电位处形成两个灵敏的二次微分溶出峰;铅在0～0.8mg·L-1,镉在0～0.4mg·L-1范围,峰电流与浓度呈良好的线性关系;铅和镉检出限分别为0.15和0.1μg·L-1,相对标准偏差≤1.39%;铅和镉加标回收率在94%～103%之间。结果表明,该甘草样品中铅和镉含量均低于国家安全标准,甘草煎煮液中铅的浸出率较高,镉的浸出率则较低,方法也适用于其它类似中药。     

铅试金法测定铅精矿及粗铅中的金、银

本试验对铅火试金富集金、银的方法进行研究.该法中的主要干扰元素有Cu、Sb、Bi、As等.结果表明As、Sb、Cu对铅试金法测定Au、Ag基本没有影响,Bi在一定范围内干扰不明显,但当Bi的含量大于5%时对Ag的测定有明显的影响.本次试验与湿法及标准加入法相比较,重现性好、可靠性强、准确度高.本方法的主要目的是解决Ag含量大于1000g/t的铅精矿及粗铅中Au、Ag含量的测定.     

原子吸收光谱法测定茶叶中铅和镉时消解方法的优化

采用多种方法对同一种茶叶进行消解,用原子吸收光谱法测定不同方法消解的茶叶中有害微量元素铅和镉的含量并进行对比,探索了茶叶中微量元素铅和镉低损耗的最佳消解条件.实验结果表明,不同的消解方式对茶叶中微量元素的测定结果影响很大.测定茶叶中铅和镉元素时,采用硝酸-高氯酸加盖浸泡过夜方法较为理想.     

分析测试经验介绍(214~218)电感耦合等离子体发射光谱法测定18K金中铅元素的谱线选择

18K金中可能含有多种杂质元素, 如铜和铅.常用的光谱分析方法中, 铅元素测试谱线易被铜、铁和金等元素干扰.建立了基于电感耦合等离子体原子发射光谱法(ICP-OES)测定18K金中铅含量的方法.测试结果表明, 在283.306 nm谱线下, 铅元素在标准曲线浓度范围内呈良好线性关系.方法检出限为0.005 6 μg/mL, 加标回收率在92.9%~102.0%之间, 相对标准偏差小于1%.采用283.306 nm谱线测试结果准确, 灵敏度高, 适用于测试18K金中铅元素含量.     

石墨炉原子吸收光谱法测定转基因棉籽中的铅镉铜铬

本文探讨了干法灰化与湿法消解-石墨炉原子吸收光谱法测定转基因与非转基因棉籽中重金属元素铅、镉、铜和铬的方法,比较了两种预处理方法对测定结果的影响.结果表明:两种方法均能满足分析测定的需要.将分析方法应用于转基因与非转基因棉籽中四种重金属含量的测定,结果显示,转基因棉籽中铅和铜的含量明显低于非转基因棉籽,镉和铬的含量与非转基因棉籽相当.     

Luminol-H2O2化学发光法测定汽油中铅

利用铅(Ⅱ)催化H2O2氧化Luminol产生化学发光的反应,采用流动注射分析技术,在分离共存干扰离子基础上,在鲁米诺中加入EDTA作为增敏试剂,有效提高了测试反应的检测灵敏度,对分解后的汽油样品中铅(Ⅱ)含量进行了化学发光法测定,铅(Ⅱ)的含量在0.5～100μg@ml-1内与发光强度呈线性关系,方法检出限达0.1μg@ml-1.     

15种中成药中有害重金属铅、镉、铜含量的测定

为了解中药重金属污染情况,测定了市售常用15种中成药中重金属铅、镉、铜的含量,其中铅、镉采用石墨炉原子吸收法,铜采用火焰原子吸收法测定.结果表明,15种中成药均不同程度被这3种重金属污染,通心络中铅、镉、铜含量都已超标,桑菊感冒片镉超标,中药重金属污染问题仍然存在.     

消渴丸中重金属铅和砷的含量测定

样品湿法消解后用石墨炉原子吸收法测定了消渴丸中铅含量,用原子荧光法测定了砷含量.结果表明,消渴丸中重金属铅含量在0.23～0.55 mg·kg- 1之间;砷含量在0.55～1.09 mg·kg- 1之间;本法测定消渴丸中重金属铅的平均回收率为96.6%,砷的平均回收率为108.4%,说明该法可用于消渴丸中铅和砷的测定,...     

Pb(Ⅱ)-KI-罗丹明B离子缔合物萃取光度法测定皮蛋中微量铅

铅是食品中的一种有害元素,在食品生产和加工过程中必须及时检测和有效的控制铅的含量,使其符合国家卫生标准.吸光光度法测定的报道甚多,其中双硫腙法的灵敏度较高,应用广泛,但该法选择性差,还须用剧毒的氰化物作掩蔽剂,造成环境污染.     

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。