高分辨率连续光源原子吸收法和离子选择电极法测定水中氟化物的比较

目的：比较高分辨率连续光源原子吸收法（HR－CS－AAS）和离子选择电极法（ISE）测定水中氟化物。方法用离子选择电极和高分辨率连续光源原子吸收分别测定水样及进行加标回收实验,比较两者的检测限、精密度、准确度等指标。并采用配对t检验检查两种方法测定水中氟的结果是否有显著差异。结果离子选择电极检测限为0.10 mg/L; RSD为2.23％～4.32％;加标回收率为96.0％～104.0％。原子吸收法检测限为0.04 mg/L; RSD为1.7％～3.6％;加标回收率为96.5％～106.0％。离子选择电极和原子吸收法同时测定24份实际水样,测定结果进行配对t检验,结果表明,两法测定水中氟无显著差异。结论高分辨率连续光源原子吸收法可用于测定水中氟,适合大批量样品测定的特点。     

硫化物和挥发性有机化合物对气相分子吸收光谱法测定水中亚硝酸盐氮含量的干扰和消除北大核心CSCD

气相分子吸收光谱法具有分析快速、维护费用低、所用试剂少等优点[1-3],已被广泛用于测定水中亚硝酸盐氮的含量[4-5],但该方法测定时会存在一定的干扰[6-7]。综合有关文献,干扰物质可分为两类:一类是具有氧化或还原性的物质,如MnO_(4)^(-)、I^(-)等,这些干扰物质是水中亚硝酸盐氮的共存物,影响体系的氧化还原平衡,不对气相分子吸收反应本身造成干扰,所以此类物质不作为干扰考虑;另一类是在反应体系和测定波长下生成有气相分子吸收的物质,如硫化物(S^(2-))、挥发性有机化合物(VOCs)等,这些物质可能会引人测定干扰,因此本工作主要针对S^(2-)和VOCs的干扰和消除开展研究。     

ICP-OES法与石墨炉原子吸收法测定饮用水中重金属元素比较

通过对比电感耦合等离子体发射光谱法(ICP-OES)与石墨炉原子吸收法(AAS)测定水中重金属的检出限、重复性、加标回收率等实验,验证两种方法的准确性,从而为饮用水中重金属的测定提供可靠的方法。结果表明,石墨炉原子吸收法测定饮用水中砷、镉、铬、铅、汞、硒检出限均低于ICP-OES法,但ICP-OES法测定线性范围宽,重复性和加标回收率均优于石墨炉原子吸收法,分析速度快,操作便捷,结果满意,是目前饮用水中重金属的测定非常可靠的方法。     

双硫腙-乙酸丁酯萃取火焰原子吸收光谱法测定水中痕量银

火焰原子吸收光谱法简便、快速,广泛用于分析环境样品中金属元素。但对于水中痕量银,却因灵敏度低而不能直接测定。因此人们寻求其它的技术途径[1],如离子交换分离 火焰原子吸收光谱法,虽然它可以满足痕量银的测定要求,但其样品处理复杂,测定时间较长;APDC MIBK萃取火焰法因其生成的络合物不稳定,测定有困难;石墨炉技术则因仪器昂贵、操作要求严格而难以推广普及。本法在文献[2]的基础上探讨了双硫腙 乙酸丁酯萃取火焰原子吸收光谱法测定水中痕量银。本法灵敏度高,操作简便、快速,回收率和精密度较好。1　试验部分1.1　原理样品溶液…     

石墨炉原子吸收光谱法测定水中痕量硒

硒是人体必需的微量元素 ,适量硒可降低癌症和心血管疾病的发病率 ,但硒含量过高可引起中毒性病变[1 ] 。对于硒的测定 ,通常采用可见光及荧光吸光光度法[2 ] ,这些方法需要用有机溶剂萃取 ,操作较麻烦 ,且采用消化法处理样品时 ,容易导致硒的挥发损失。火焰原子吸收光谱法测定水中硒 ,灵敏度较低 ,而将以钯等作改进剂的石墨炉原子吸收法 [3]用于水中硒的测定 ,吸光度虽有所提高 ,但灵敏度仍难以满足水中痕量硒的测试要求。本文采用平台石墨管与基体改进剂结合技术 ,对水中痕量硒测定 ,结果满意。1　试验部分1 .1　主要仪器与试剂美国 TJA…     

石墨炉原子吸收法间接测定水中碘

石墨炉原子吸收法直接测定金属元素,灵敏度很高,直接测定非金属元素碘则存在困难。本文参考文献[1]提出用石墨炉原子吸收法间接测定水中碘,以代替操作繁锁的催化比色法与气相色谱法[2]。方法原理是通过加入硝酸汞,使之与水中碘生成较难热解离的碘化汞,测定汞含量便可间接求得碘含量。过量的汞可通过干燥灰化阶段预先排除,不干扰碘化汞吸收峰的出现。本法测定碘含量范围为1～10μg·L~(-1),对碘2和10μg·L~(-1)重复测定五次的相对标准偏差分别为6.0％和3.2％。平均回收率分别为95％和96％。检出限为1μg·L~(-1)。1 试验部分1.1 试剂与仪器 去离子水:电阻率达2M·cm以上 过氧化氢:3.0％（10d内有效） 碘化物标准溶液:100μg·ml~(-1),称取干燥器中放置24h的优级纯碘化钾0.1308g,溶于纯水中并定容1L。使用时稀释成0.025μg·ml~(-1)工作液。 硝酸汞溶液:0.4g·L~(-1),称取硝酸汞0.20g溶     

APDC-MIBK萃取火焰原子吸收法测定水中铜、镉、铅

重金属及其化合物毒性较大,进入人体后会引起各种生理变化,尤其对神经和心血系统有严重的危害性。因此对水中重金属进行分析具有重要的意义。直接火焰原子吸收法测定重金属的灵敏度不高,一般大于0.1mg/L[1],直接测定水样中微量铅较困难;石墨炉原子吸收法测定铅的灵敏度比直接火     

火焰原子吸收光谱法测定聚氯化铝中锰

火焰原子吸收法测定锰具有选择性好、操作简便等优点.但由于净水剂聚氯化铝中存在大量铝基底,在火焰中生成难熔的氧化物与锰形成混晶或固熔体,影响了锰的原子化,故在一般条件下不能以直接原子光谱法准确测定净水剂聚氯化铝中锰含量.目前,一般采用萃取-原子吸收法及化学法测定聚氯化铝中锰.但此两法有费时或所用萃取剂MIBK有刺激性气味等缺点.我们参照文献[1],在聚氯化铝样液中加入磺基水杨酸作Al~(3 )的配合剂,拟定了火焰原子吸收直接测定聚氯化铝中锰的新方法.该法有效地消除了大量铝     

原子吸收法间接测定乳制品中乳酸的研究

乳酸作为酸味剂是乳制品的重要成分之一。它是由淀粉接种乳酸菌发酵的产物[1,2],也是判断乳制品质量和新鲜度的重要指标之一。乳酸的测定方法比较常用的有滴定法[2]和液相色谱法[3,4]。平时工作中,乳制品里面存在的大量白色乳浊基体使滴定法难于进行,同时给液相色谱法带来冗长乏味的、复杂的操作步骤。由于共存基体对乳酸测定的严重干扰,用上述方法不能快速、及时地测定日益增加的乳制品的乳酸含量。原子吸收法是测定金属元素的简便、快速、准确的方法。用原子吸收法测定有机化合物已有不少研究[5～11],用原子吸收法测定乳酸的也有报道[…     

废旧F732测汞仪部件与原子吸收光度计联用测定水中痕量汞

水中痕量汞的测定目前多采用冷原子吸收法。而借助原子吸收分光光度计的标尺扩展功能较一般测汞仪具有更好的灵敏度。本文利用废旧F732测汞仪的薄膜泵和石英管吸收池作为汞的原子化装置,使汞在普通原子吸收分光光度计上的测定变得简便、易行。用于水中痕量汞的测定,得到满意的效果。     

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。     

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.     

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.     

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。     

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.     

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。