Al3+对电位滴定仪测定游离酸的干扰及其消除研究

溶液中Al3+易水解,对游离酸的测定存在严重干扰。本文以NaF溶液掩蔽Al3+,用自动电位滴定仪测定含Al3+溶液中的游离酸含量,通过溶液化学分析论证了NaF溶液掩蔽Al3+的可行性。NaF掩蔽-自动电位滴定法测定含Al3+溶液中游离酸含量的精密度实验RSD小于2.0%,方法的加标回收率在98.00%～103.00%之间,与手动滴定法对比可靠性检验结果t=0.25;以上结果表明该方法具有准确度高、重复性好的优点。     

量气法的改进及应用

通过在反应管(瓶)上端加一恒压分液漏斗以改进一般量气法中隔离反应物的方式称为改进量气法.应用改进量气法对Mg摩尔质量、Al合金中Al含量、无水Na2CO3基准物和工业纯碱总碱度以及钙片中CaCO3含量进行了测定,并将其测定结果与其他测定方法的实验结果进行了比较.结果表明,改进量气法能更方便、简单、快速、环保地应用于有定量气体产生的有关常数测定以及一些定量分析的实验中.     

浊点萃取掺氧空气-乙炔火焰原子吸收光谱法测定痕量铝

本文提出铬天青S作为掺氧空气-乙炔火焰原子吸收光谱法(FAAS)测定痕量Al 3+的化学改进剂,又作为萃取Al 3+的络合剂。优化了浊点萃取痕量Al 3+的分离富集条件,及掺氧空气-乙炔FAAS测定Al 3+的参数。据此,建立了选择性好﹑简便快速测定水样中痕量Al 3+的新方法。方法的检出限(3σ)为4.5μg/L,测定Al 3+的线性范围为15~1 600μg/L,相对标准偏差(RSD)是3.8%(cAl=100μg/L,n=7),加标回收率在96.1%~105.9%之间,理论富集倍数为50。     

电感耦合等离子体原子发射光谱（ICP-AES）法测定高纯氧化铟中7种杂质元素

采用电感耦合等离子体原子发射光谱(ICP-AES)法测定高纯氧化铟中杂质元素Al、Cd、Cu、Fe、Pb、Tl和Zn等的含量。使用盐酸(1+1)溶解高纯氧化铟试样,基体铟的干扰采用基体匹配法消除,被测元素之间没有光谱干扰。对方法进行加标回收实验和精密度实验,方法加标回收率在92.2%～110%,测得结果的相对标准偏差在0.57%～5.8%,可以满足高纯氧化铟中Al、Cd、Cu、Fe、Pb、Tl和Zn等杂质元素含量的测定要求。     

Al-0.30%Sc-Zn-Cu四元系富铝角450℃等温截面的相关系

采用合金法,通过扫描电镜组织观察、能谱分析和X射线衍射分析测定Al-0.30%(质量分数)Sc-Zn-Cu四元系富Al角450℃等温截面的相关系。结果表明:在Al-0.30%Sc-Zn-Cu四元450℃等温截面图中存在α(Al)+Al3Sc,α(Al)+W两个两相区,α(Al)+Al3Sc+W一个三相区。450℃时,Al-0.3%Sc-Zn-Cu四元系中W相的出现取决于Cu含量;当Cu含量大于1.0%,该四元系出现W相;Cu含量处在1.0%～3.0%,α(Al),Al3Sc和W三相共存;当Cu含量大于4.0%,α(Al)和W两相共存,Al3Sc相不出现。     

茶叶和蔬菜中铅的同位素稀释电感耦合等离子体质谱的测定

采用同位素稀释电感耦合等离子体质谱(ID-ICP-MS)法测定了铅的含量,通过对茶叶标准物质(GBW-07605)中铅的测定,考察了方法的准确度和精密度,比较了同位素稀释法与普通外标定量法的测定结果。在5mLHNO3～0.5mLHF～1mLH2O2的消解体系中,ID-ICP-MS法测量茶叶中铅的回收率可达97.7%,相对标准偏差(RSD)小于1.2%。实验对市售的12种茶叶和10种蔬菜中Pb进行测定,铅含量符合相应国家标准的样品分别占总样品数的83%和90%。该法适合于植物样品中微量铅的测定。     

ICP-OES法测定镍铬合金中Si、Mn、Fe、Ti、Al、Cu

本文建立了电感耦合等离子体原子发射光谱测定镍铬合金中Si、Mn、Fe、Ti、Al、Cu元素含量的分析方法。确定了溶样方法和分析谱线,采用基体匹配消除干扰。对方法精密度和准确度进行实验,实验结果表明,各元素的相对标准偏差均小于3%,加标回收率在86.8%～106.9%之间,镍铬合金(GBW(E)020023)标准物质的各元素测定结果均与标准值一致。所建方法快速、准确,适用于镍铬合金中多元素同时测定。     

微乳液增敏光度法测定中草药中微量硒

研究了在非离子微乳液介质中,硫氰酸盐罗丹明B 明胶体系分光光度法测定微量硒的方法。实验表明,当微乳液组成为V(OP乳化剂) +V(正戊醇) +V(正庚烷) +V(水) =1 5 0 +0 1 1+0 41 +97 98时,体系的表观摩尔吸收系数达1 3 0 1×1 0 6 L·mol- 1·cm- 1,灵敏度比在OP溶液中有显著提高,使该法成为少有的超高灵敏度测定硒的光度法之一。Se (Ⅳ)含量在0～0 0 5 μg·mL- 1范围内符合比耳定律,对0 0 2 μg·mL- 1Se(Ⅳ)平行测定1 1次,测得相对标准偏差为0 945 %。应用于中草药中微量硒的测定结果令人满意     

硫代苹果酸功能化的纳米银分光光度法测定面制食品中铝含量

制备了硫代苹果酸功能化的银纳米颗粒(TMA-AgNPs),随着Al3+浓度的增加,TMAAgNPs上的功能基团与Al3+发生相互作用导致TMA-AgNPs的聚集,溶液颜色由黄色逐渐变为橘红色,据此采用分光光度法测定面制食品中铝含量。优化的试验条件如下:①5.0mmol·L~(-1)硫代苹果酸溶液的用量为2mL;②修饰反应时间为10min;③Al3+与TMA-AgNPs的作用时间为2min。Al3+的线性范围为0.10～5.00μmol·L~(-1),检出限(3S/N)为0.031μmol·L~(-1)。方法用于面制食品样品的分析,加标回收率为97.0%～105%,测定值的相对标准偏差(n=5)为2.1%～3.1%。     

一种天然显色剂在光度法测定铝中的应用

自紫甘蓝中提取的花青素与Al3+发生络合反应的产物颜色与花青素本身不同,利用该性质可以建立一种定量测定Al3+的新方法.花青素在pH4.7的乙酸-乙酸钠缓冲体系中与Al3+显色,络合物最大吸收波长580nm.Al3+含量在0.1～1.0mg/25mL范围内与吸光度呈良好的线性关系,相关系数R2=0.9995,络舍物摩尔吸光系数236L·mol-1·cm-1,铝离子浓度为25μg/mL时方法相对标准偏差2.1％,定量检出限0.059mg/25mL.方法应用于国家土壤标准样品(GBW07408)的测定,土壤样品加标回收率在98％～109％之间.方法可用于低常量和微量铝的定量测定.     

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。     

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.     

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。     

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.     

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.