有机化合物中氧的光度库仑微量测定法

有机化合物在900℃高温,于氮气流下瞬间裂解生成的各种氧化物,经900～950℃的铂碳层还原成一氧化碳。一氧化碳再经过350℃氧化铜层氧化成二氧化碳,最后用20mA恒电流对二氧化碳进行库仑滴定,由光度检测作终点指示。每次分析时间为15分钟,标准偏差为0.5％。本法已应用于常规分析。对含磷、铁、铜等金属有机化合物,在样品上复盖一些铂碳也可获得满意的分析结果。     

高氟有机化合物中碳氢元素的微量测定

本文研究了含高氟有机化合物中碳氢元素微量测定的条件。提出使用高温燃烧及混合氧化剂,以避免四氟化碳的形成。燃烧温度为950～1000℃,氧气流速每分钟为12毫升。     

有机化合物中硫元素微量测定方法的一些改良

对目前普遍应用的氧瓶燃烧分解样品，钡盐法滴定有机硫的分析方法进行了规范化．探讨了溶液pH对测定的影响，研究了磷元素及氟元素对测定的于扰．并建立了适用于测定含磷有机化合物中硫元素的钡盐滴定法该法，该法简便快捷，准确可行、结果令人满意。     

有机化合物中硫元素微量测定方法的一些改良

作为有机元素微量定量分析方法系列报道之一,本文对目前普遍应用的氧瓶燃烧分解样品,钡盐法滴定有机硫的分析方法进行了规范化,探讨了溶液pH对测定的影响,检测了磷元素及氟元素对测定的干扰,并建立了适用于测定含磷有机化合物中硫元素的钡盐滴定法.针对钡盐法测定低含量硫元素时误差较大,本文建立了基于氯冉酸钡与硫酸根离子反应的分光光度法,该法准确可行,适用于测定低含量有机硫元素.     

元素有机化合物在有机合成中的应用

本文简要介绍磷、硫、砷、硅、硼和锡有机化合物在有机合成应用中研究得较活跃的一些例子,并着重讨论应用元素有机化合物合成立体专一性、光学活性和生理活性的化合物。     

单柱离子色谱的研究-有机化合物中氯,溴元素的微量分析

本文介绍用单柱离子色谱法对有机化合物中氯和溴进行微量分析。样品经氧瓶法燃烧分解,被吸收于含双氧水的苯二甲酸氢钾溶液中的Cl-和Br-,可在单柱离子色谱的分离柱上得到分离,然后用电导检测器检测,用峰面积积分进行定量。本法简便、快速,可同时测定氯、溴两种元素。分析标准偏差分别为±0.39%和±0.59%。     

卡尔费休库仑法测定微量水的装置改进

针对工业生产中聚合级原料气体中微量水检测中的问题,对卡尔费休库仑装置进行了改进。利用改进后的装置测定聚合级异丁烯、氯甲烷中微量水,平均相对标准偏差为5.8％,回收率为92.4％～103.7％;测定六氟化硫气体中痕量水,其测定结果与五氧化二磷电解法基本相符。通过潮湿环境实验,证明了改进后的装置适宜在潮湿环境下测定气体中的微量水,操作简便,测定结果可靠。     

微库仑法测定硫注意事项

根据微库仑法测定硫的基本原理和仪器本身的特点，分析了微库仑法测定硫时，电流、磁场、温度、气体流量、滴定池、电解液等因素对测定结果的影响，探讨了影响机理，提出了应注意的事项。     

库仑滴定法测定冶金焦炭中硫

硫含量作为评价煤质和焦炭质量的重要技术指标之一，其测定在煤焦分析中占有重要的位置。目前，我国现行焦炭中全硫的测定方法有重量法(艾士卡法)和高温燃烧中和法。重量法是一种通用的标准方法，可用于仲裁分析。其优点是测量结果准确，重复性好；缺点是试验周期长，操作比较繁琐。     

电生溴库仑滴定法直接测定渣油中硫醚硫的研究

本文提出了在甲苯－冰乙酸－乙醇－ＮａＢｒ电解液中电生溴库仑滴定电位法指示终点直接测定渣油中硫醚硫的新方法。该电解液对渣油样溶解性能好，终点电位突跃大，结果准确。     

Microdetermination of Adjacent Hydroxyl Groups in Organic Compounds

Abstract

A simple method is described for determination of the number of adjacent hydroxyls in an organic compound. This method involves a digestion of the sample with hydriodic acid in a closed tube. The amount of iodine produced in the digestion (i.e., N-1 moles) is related to the number of adjacent hydroxyls in the molecule (i.e., N).     

GC and Mass-Spectrometric Comparison of Organo Sulfur Compounds in Two Varieties of Iranian Garlic

Abstract

Garlic antibiotic action is well known; it is reputed to offer protection against coronary thrombosis and atherosclerosis exhibiting antioxidant and anticancer effects. ^1,2 In this work ¹ H NMR and gas chromatography in conjunction with mass spectrometry have been used for the identification and determination of these compounds in two varieties of Iranian garlic [Allium sativum var. sativum (I) and Allium sativum var. holmense (II)]. The organosulfur compounds in (I) exhibiting a concentration higher than 1% are diallyl sulfide (1.3%), diallyl disulfide (8%), methyl allyl disulfide (19%), methyl allyl trisulfide (3.2%), diallyl trisulfide (5.5%), diallyl tetrasulfide (2%), 2,3-dimethyl thiophen (1.8%), 5-methyl-1,2,3-thiadiazol (5%), and 1,2-ditiolan-3-carboxilic acid (1.5%). The amount of organosulfur compounds in (II) are diallyl disulfide (2%), methyl allyl trisulfide (6.3%), diallyl tetrasulfide (5%), and cyclopentanthiol (2.5%).     

Coulometric Determination of Total Cyanide in Effluent and Wastewater

Abstract

A simple procedure for the determination of low levels of total cyanide in effluent samples has been developed. After distillation of the cyanide from the sample, as hydrocyanic acid, the cyanide is determined with coulometrically generated iodine using a biamperometric end point detection system. As little as 0.06mg/l total cyanide can be measured using the procedure. The method obviates the need for calibration curves and does not require special reagents.

Silver (I) was determined to be an effective catalyst for the decomposition of bound cyanides in the distillation procedure.     

Simple Device for Isolation of Organic Compounds from Water

Abstract

A simple device for isolation of organic compounds from aqueous samples has been designed and its operating parameters tested during bioth periodic and continuous operation using isolation of organochlorine compounds as an example.

A stream of an aqueous sample is pumped at elevated temperature by a piston pump to an unit for expransion of the liquid phase surface, where the liquid is sprayed on the walls of the unit and flows down freely.

Organochlorine compounds passing to the gaseous phase are purged with a stream of purified air, oxidied and the chlorides formed are determined coulometrically. The designed device, due to its simplicity, can be built and employed in each averagely equipped laboratory.     

Assessment of Additives for Nitrogen, Carbon, Hydrogen and Sulfur Determination by Organic Elemental Analysis

 A survey is reported on the use of additives in organic elemental analysis of compounds containing functional groups that may compromise the combustion process. 28 substances containing the following functional groups were selected: organic fluorine, hexafluorophosphate, tetrafluoroborate, tetraphenylborate, sulfonate, phosphine, nitrile, carbide, organometallic. Six additives (powdered silver, silver tungstate with magnesium oxide, silica oxide, tungsten (VI) oxide with magnesium oxide, powdered tin, cerium (IV) oxide) in various sample:additive ratios were assayed. Silver tungstate with magnesium oxide (mixture 1:1, w/w) turned out to be most efficient for the analysis of nitrogen, carbon, hydrogen and sulfur for almost all the compounds assayed. Author for correspondence. Received August 2, 2002; accepted December 12, 2002 Published online May 19, 2003     

A Simple Coulometric Method for Determining Cu[II] and Cu[I] Contents in Various Solid Samples

Abstract

Determination of copper individual oxidation states (Cu[II] and Cu[I] in various solid samples is a rather difficult problem. Results are here presented to demonstrate that constant current coulametric techniques are useful to realize these determinations with good analytical characteristics. The analytical equivalence points obtained are based on the reversible electron transfer mechanisms: Cu[II] + 3 HC1 + 2 e CuCl^2? ₃ + 2H⁺ and : CuCl^2? ₃ +e = Cu(O) + 3 Cl^?, respectively, after quantitative dissolution in aqueous HC1 6 M. Cyclic voltammetric measurements with a carbon paste electrode are made to characterize the electron transfers involved and to investigate the analytical utility of the technique in various media. Analytical determinations are given, e.g., in the analysis of the CuO/Cu₂ O content of various samples.     

金属有机化合物中过渡金属的原子吸收分光光度法测定

本文报导应用火焰原子吸收分光光度法对金属有机化合物中过渡金属铜、镍、钴、铁、钼及铬的定量测定。我们将金属有机化合物溶解在适当的有机溶剂或水中,不必分离基体,即可用标准加入法直接进行测定。操作简单,速度快,相对误差<0.4％。     

TS-1/过氧化氢催化体系中有机硫化物的选择氧化

 研究了TS-1/过氧化氢催化体系中几种典型有机硫化物的选择氧化脱除. 结果表明,噻吩和2-甲基噻吩仅在水或叔丁醇溶剂中才能被有效氧化脱除,且两者的反应历程不同. 噻吩分子中的硫原子先被氧化,2-甲基噻吩分子中的噻吩环先被氧化. 当过氧化氢与硫化物摩尔比为4时,噻吩和2-甲基噻吩均可被氧化为硫酸. 采用甲醇、乙腈和水作溶剂时,甲基硫醚和丁基硫醇均可被选择氧化脱除. 由于存在空间位阻,苯并噻吩、二苯并噻吩及4,6-二甲基二苯并噻吩在TS-1/过氧化氢体系中均不能被有效脱除.