高铬耐磨铸铁中磷的快速分析

我厂研制的双金属缸套的内套使用的是高铬耐磨铸铁 ,铬的质量分数一般为 1 6%～ 1 8% ,在分析磷含量时考虑铬对测定的影响 ,一般采用高氯酸溶样 ,盐酸挥发铬以消除铬的干扰 ,但这种方法试样处理时间长 ,不易掌握 ,日常分析中发现铬对磷有时仍有干扰。为了车间生产的需要 ,试验用高氯酸冒烟氧化溶解试样 ,在高氯酸 -硫酸介质中 ,氟化钠 -氯化亚锡钼蓝光度法测定高铬铸铁中的磷 ,操作简便、快速、准确 ,完全满足实际生产的需要。1　主要试剂与仪器钼酸铵溶液 :50 g.L- 1亚硫酸钠溶液 :1 0 0 g.L- 1 ,当天配制。高锰酸钾溶液和亚硝酸钠溶液 :…     

含铌钽钢中硼的比色测定

用次甲基蓝比色测定某些含铌钽钢中微量硼时,常常遇到如下困难:铌钽的严重干扰;王水分解试样时氯化硼的挥发损失;某些硼化物如碳化硼、氮化硼以及铌钽的金属间硼化物等不易被王水和硫酸所分解等。为了解决这些问题,本文研究了用焦硫酸钾熔融试样,以水解方式分离铌钽,方法简单,效果较好,避免了卤化硼的挥发损失,并解决了难溶硼化物的溶样问题。本法适用于含铌钽的镍基、铁基和部分钴基合金中微量硼的测定。     

炉渣中Cr_2O_3的快速比色测定

炉渣中Cr_2O_3的分析方法较多.一般有容量法和比色法。测定时,在分解试样后一般用高氯酸冒烟或高锰酸钾将铬氧化成高价,也有用硝酸银作催化剂,以过硫酸铵氧化铬至高价。但用高氯酸氧化使结果稍偏低,而用高锰酸钾或过硫酸铵氧化则需用铬标准溶液与试样同时作平行分析,使操作繁琐。本法对此作了改进。对于酸不溶性炉渣试样,则分取经硼酸-碳酸钠熔融后的盐酸介质溶液,用硝酸驱除Cl~-后再用酸溶性炉渣的分析步骤即可。试验结果表明,方法准确可靠。简便易行,并可节省时间和试剂主要试剂与仪器混合熔剂两份无水碳酸钠和1份硼酸充分研细混匀。     

电感耦合等离子体原子发射光谱法测定某些特殊试样中痕量铬（Ⅵ）——共沉淀法快速分离铬（Ⅲ）

电感耦合等离子体原子发射光谱法(ICP-AES)应用于某些特殊试样(特别试液背景色泽很深或略带混浊者)中铬(Ⅵ)的测定.试样溶液中共存的铬(Ⅲ)及一些其他金属离子的干扰,借在PH 9.5的氨性溶液中以Fe(Ⅲ)离子作载体共沉淀分离予以消除,用ICP-AES法测定滤液中铬(Ⅳ).试验表明:铬(Ⅲ)共存量达100 mg·L-1时,经沉淀分离后不影响铬(Ⅵ)的测定,铬(Ⅵ)的回收率接近100%.此方法的检出限(3σ)为0.054 mg·L-1,应用所提出的方法测定了一种黄色油漆中在铬(Ⅲ)共存下的铬(Ⅵ),平行7次测定,相对标准偏差为1.3%.     

原子吸收分光光度法测定金属铬中铁

金属铬中铁的测定方法已报导的有络合滴定法、电位滴定法和分光光度法等。在这些方法中由于铬和其他共存元素干扰,都需分别采用挥发除铬、萃取、沉淀或离子交换等方法进行分离后才能测定,因此上述方法都较繁琐、费时。本文研究了原子吸收分光光度法测定金属铬中铁的条件。在对铁的干扰试验中,较现有文献增多了元素种类及加大了共存量的影响试验,探讨了某些干扰原因。建立的方法比较简便、快速、不需要分离,试样经盐酸分解后即可测定。方法精确度好,标准偏差为     

灯盏花中重金属元素的化学形态及分布

应用火焰原子吸收光谱法(测定铅、铬、镉)及原子荧光光谱法(测定汞、砷)对灯盏花中重金属的化学形态及其分布进行了研究。0.5g经过预处理的试样用浓硝酸消解并经高氯酸冒烟至近干,用水溶解残盐并定容为25mL。在此溶液中分别用上述两方法测定5种金属元素的总量。分别用5种不同萃取溶剂,即乙醇-水(80+20)混合溶液、亚沸重蒸馏水、1mol·L-1氯化钠溶液、乙酸(2+98)溶液及0.6mol·L-1盐酸溶液,对10g试样进行连续超声萃取。各次所得萃取液分别用硝酸和高氯酸按上述方法处理后测定其中5种金属的含量。文中给出了上述金属元素在各种化学形态中的含量及分布状态,此次结果对评价中草药的生物功能及毒性能有参考价值。     

测定石油焦挥发分的技术条件

挥发分作为评价石油焦质量的重要技术指标之一,其测定在石油焦分析中占有很重要的位置.由于挥发分是在无空气通入的情况下,将试样加热至(850±10)℃,并保持7 min,按照损失总质量与蒸发水分损失之间的差来确定挥发分.由于其技术条件不易控制而常常造成测定结果不准确.经过实践,总结出准确测定石油焦挥发分的技术条件.     

过硫酸铵氧化滴定法测定高铬铸铁中铬含量

高铬铸铁中的铬大部分以固溶体形式存在,另一部分是以碳、氮化合物等形式存在。碳、氮化合物用酸分解极其困难,只有在加热冒高氯酸烟或在加热冒硫酸烟时滴加硝酸才能完全分解。测定高碳高铬样品中铬时不允许长时间冒高氯酸烟,一般在冒硫-磷酸烟时滴加硝酸氧化来破坏其碳氮化合     

铜合金(含锡、锰、铁)中铝的测定

应用络合滴定法测定铜合金中铝的关键是如何分离干扰元素。常用的有铜试剂分离、氢氧化钠分离、电解分离后用氟化钠析出等等。这些分离方法不仅手续繁杂,而且也不能将所有的干扰元素分离除去,特别是对含锡的铜合金,采用硝酸分解并蒸干的方法,正如有的文献所指出的[理化检验,(1),29(1973)],在硝酸溶液中形成的偏锡酸沉淀会吸附部分铝,使铝受到损失,并易为人们所忽略。为克服锡的干扰,试样经盐酸、过氧化氢分解后,用高氯酸冒烟,使偏锡酸沉淀完全,并且不吸附铝。经多次试验,高氯酸冒烟时间为1—5分钟,测得数据不变。高氯酸的加入量以4毫升最佳。所获结果令人满意,很有实用价值。     

金属材料分析方法的选择和施行 第六讲 金属材料中稀土元素的测定（续）

镍铬合金试样的溶解:称取试样0.1000g置于125 mL锥形瓶中,溶于王水3～5 mL中,加入浓高氯酸1～1.5 mL,蒸发至冒烟并呈重铬酸盐的砖红色,随即乘热滴加浓盐酸使铬(Ⅵ)以氯化铬酰(CrO2Cl2↑)形态挥发除去.     

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。