紫外光谱法测定印制线路板废水中的铜

白杨素在紫外区内具有强吸收,Cu2+加入后会导致其吸光度显著下降,且吸光度的降低与Cu2+的浓度呈良好的线性关系,基于此建立了紫外光谱法测定Cu2+的新方法。通过对缓冲溶液体积、p H、白杨素浓度等进行考察和优化,在p H 8.28、9.0×10-2mol/L的六亚甲基四胺(HM TA)-HCl缓冲溶液中,4.0×10-8~1.0×10-6mol/L范围内,Cu2+浓度与吸光度降低成正比,线性方程为ΔA=0.508 c-0.0147(10-6mol/L)(R=0.99604),检出限为7.08 nmol/L(S/N=7),对4.0×10-8mol/L Cu2+溶液平行测定7次,ΔA的相对标准偏差为4.0%。对印制线路板废水中的铜进行了测定,测得结果与EDTA滴定法基本一致。     

(Au)核(Ag)壳纳米微粒光度法快速检测过氧化氢

以粒径为10 nm的纳米金为晶种, 用柠檬酸钠还原硝酸银制备了平均粒径为30 nm的(Au)核(Ag)壳纳米微粒, 用高速离心纯化除去过量的柠檬酸三钠获得了较纯的(Au)核(Ag)壳纳米微粒, 其吸收峰位于393 nm处. 在pH 4.4的HAc-NaAc缓冲溶液中, Fenton反应产生的羟基自由基可以氧化(Au)核(Ag)壳纳米微粒银层生成银离子, 导致393 nm处的吸光度降低. H2O2的浓度(c)在6.58～421.1 μmol/L范围内与393 nm处的吸光度降低值ΔA 393 nm呈良好的线性关系, 回归方程为ΔA393 nm=0.00111c+0.0210, 相关系数为0.9908, 检出限为1.73 μmol/L. 本方法用于废水样品测定, 结果满意.     

协同增敏Fe(Ⅱ)-邻二氮杂菲阻抑光度法测定微量过氧化氢

在乙酸介质中,H2O2对Fe(Ⅱ)-邻二氮杂菲体系的显色反应有明显的阻抑作用,表面活性剂协同增敏有效提高体系吸光度,据此建立了测定微量H2O2的新方法。测得最大吸收波长500~510 nm,H2O2质量浓度在0.05~0.3μg/m L范围内与吸光度递减呈良好的线性关系,方法的相对标准偏差为0.24%~0.28%;回收率为98.7%~102.8%。方法已用于测定消毒液中微量H2O2。     

双波长动力学光度法测定邻苯二酚的研究

Fe(Ⅲ)能够催化H2O2氧化中性红和灿烂甲酚蓝混合体系并使其褪色,加入邻苯二酚以后,该催化氧化褪色反应的速度明显提高.分别测定540 nm和640 nm处加入邻苯二酚和没有加入邻苯二酚体系的吸光度变化,发现吸光度的变化之和(△A)与邻苯二酚的浓度之间存在线性关系.研究了反应体系的吸收光谱,优化了实验条件,建立了双波长动力学光度法测定邻苯二酚的新方法.该方法测定邻苯二酚的线性范围为0.16～1.44 mg/L,检出限为0.05 mg/L.方法用于废水样品中邻苯二酚的测定,结果满意.     

H_2O_2-天青Ⅱ催化动力学光度法测定痕量铜(Ⅱ)

在氨水介质中及加热条件下,痕量铜(Ⅱ)对H2O2氧化天青Ⅱ的褪色反应具有强烈的催化作用.探讨了最佳实验条件,据此建立了催化动力学光度法测定痕量铜(Ⅱ)的新方法.在选定的实验条件下,非催化反应与催化反应的吸光度差值△A与铜(Ⅱ)离子的质量浓度在16～56 μg/L范围内有良好的线性关系,检出限为9.36×10-11 g/mL.并且测定了催化反应的动力学参数,反应为准一级反应.在75℃下的表观速率常数为K'=4.04×10-3 8-1,表观活化能为74.54 kJ/mol.方法用于人发中痕量铜(Ⅱ)的测定,回收率在99.7%～100.0%之间.     

食品中残留过氧化氢的测定

利用猪血红蛋白(pHb)的催化特性,以3,3’,5,5’-四甲基联苯胺(TMB)为底物,建立了一种催化光度终止法测定食品中残留过氧化氢(H2O2)的方法。实验考察了终止剂的类型和浓度、反应时间、pH、温度、TMB浓度对H2O2检测的影响。在选定的反应条件下,体系吸光值与H2O2浓度在1.46×10-6～2.91×10-5mol/L范围内呈良好的线性关系,线性相关系数为0.9958,方法对H2O2的检出限为5×10-7mol/L,测定标准偏差为4.9%,样品的加标回收率为92.9%～103%,利用该方法进行了实际样品中的H2O2分析,结果与国标法无显著性差异。     

磷钼蓝分光光度法测定药物中异烟肼

建立了磷钼蓝分光光度法测定异烟肼的新方法。实验表明:在0.24 mol/L H2SO4介质中,PO43-与Mo7O246-反应生成磷钼杂多酸([H2PMo12O40]-),它能被异烟肼还原形成磷钼蓝,其最大吸收波长为710 nm。磷钼蓝的吸光度与异烟肼浓度呈良好线性关系,其线性范围为0.64～160 mg/L,线性回归方程为A=0.04582+0.01047ρ(mg/L),线性相关系数R=0.9996,表观摩尔吸光系数ε=1.8×103L/(mol.cm)。本法已用于药片中异烟肼含量测定。     

基于聚酰胺-胺功能化碳纳米管负载钯纳米粒子的过氧化氢传感器

采用电化学法将钯纳米粒子(PdNPs)沉积在第四代聚酰胺-胺树状大分子(G4.0 PAMAM)功能化碳纳米管(MWCNTs)复合材料(G4.0-MWCNTs)修饰的玻碳电极表面,构建了一种新型过氧化氢(H2O2)传感器。采用场发射扫描电镜、循环伏安法和电化学阻抗谱对修饰电极进行表征,结果表明,大量高分散的PdNPs沉积在G4.0-MWCNTs修饰的电极上,修饰电极对H2 O2还原具有优异的电催化性能。在优化条件下,H2 O2浓度在1.0×10-9~1.0×10-3 mol/L范围内与电流响应呈线性关系,检出限为3×10-10 mol/L (S/N=3),测定血清实样加标回收率在96.7％~103.1％之间。     

普鲁士蓝-多壁碳纳米管复合材料修饰电极测定过氧化氢

利用电化学方法在多壁碳纳米管(MWCNT)修饰的玻碳电极表面聚合一层普鲁士蓝(PB)(PB/MWCNT/GCE),制备了一种新型的过氧化氢(H2O2)传感器。研究了该传感器对H2O2的电催化作用。讨论了支持电解质种类、酸度、修饰层厚度、电位和扫速等对H2O2响应的影响。研究表明,该传感器在以1.0mol/L KCl为支持电解质的磷酸盐溶液(pH=2.0)中,对H2O2具有明显的催化效应,测定的线性范围变宽,在2.9×10-6~8.8×10-2mol/L范围内还原峰电流与H2O2的浓度呈良好的线性关系,相关系数为0.9949;检出限为1.4×10-6mol/L。该电极用于医用消毒水中H2O2的测定,结果令人满意。     

锆(Ⅳ)-偶氮胂Ⅲ褪色光度法测定茶叶和尿样中的草酸

建立了一种快速、简便及选择性好的测定茶叶和尿样中草酸的方法。该法基于在1.3mol/L的HCl介质中,锆(Ⅳ)与偶氮胂Ⅲ形成配比为1∶1的蓝绿色络合物,草酸的加入使溶液的吸光度降低,在一定的范围内,草酸的浓度与吸光度的降低成正比。草酸浓度在5.5×10-6～1.1×10-4mol/L范围内线性关系良好,相关系数为0.997,检出限(S/N=3)为2.30×10-6mol/L。方法用于一些生物样品中草酸含量的测定,结果满意。本法简便、快速,易被一般实验室采用。     

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.     

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.     

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.