磺胺甲唑的库仑滴定研究

本文报告了用库仑滴定法测定磺胺甲口恶唑的含量，以０．５ｍｏｌ／Ｌ溴化钾－１ｍｏｌ／Ｌ硝酸钾－１ｍｏｌ／Ｌ乙酸（１＋１＋１Ｖ／Ｖ）混合液为电解液，在阳极电生溴，磺胺甲口恶唑分子中苯环上氨基邻位氢被溴取代。以电生溴过量电流上升法指示终点，根据法拉第定律计算，该取代反应电子数ｎ值为２，从而建立了磺胺甲口恶唑含量测定的新方法。     

库仑滴定法测定烟叶提取物中茄尼醇

本文提出用库仑滴定法测定茄尼醇。以含有1mol·L－1KBr的78％（V／V）醋酸溶液为介质，以5mA恒电流为电解电流，对布尼醇进行库仑滴定，用双铂电极电流法指示滴定终点，得到满意结果．方法简便、准确，不需要标准溶液，不需要昂贵仪器。     

库仑滴定法测定新洁尔灭溶液中溴化苄烷铵的含量

应用库仑滴定法测定了新洁尔灭溶液中溴化苄烷铵的含量。用0.09mol·L-1硝酸溶液和0.5%(w)明胶溶液以体积比10比1混合的混合溶液作电解液,银棒作阳极进行恒电流电解,电解电流为10mA。电解过程中,从银电极释放出的Ag+与试液中溴化苄烷铵的Br-反应生成沉淀。Br-被完全沉淀时,电流上升,滴定到达终点,根据法拉第定律计算溴化苄烷铵的含量。溴化苄烷铵的质量浓度在0.422 8~1.480g·L-1范围内与所消耗的电量之间呈线性关系。对同一样品的分析,本方法的测定结果与四苯硼钠滴定法的测定结果相符,本方法测定结果的相对标准偏差(n=6)为0.9%。用标准加入法进行回收试验,测得回收率在99.6%~102%之间。     

用库仑法分析硅橡胶中乙烯基的含量

高分子量硅橡胶中乙烯基的含量可用库仑法间接测定。样品溶解后先和标准溴溶液反应,过量的溴用标准丙烯醇溶液除去,过量的丙烯醇又用库仑法分析.硅生胶中0.2％的乙烯基测定的精密度为5.5％.硫化胶中残余的乙烯基亦可用溴溶液较长时间溶胀反应而后分析。     

柱前衍生反相高效液相色谱分离和测定氨基酸：用N—羟基琥珀酰？…

以Ｎ－羟基琥珀酰亚胺－α－萘乙酸酯（ＳＩＮＡ）为氨基酸的柱前衍生试剂,反相高效液相色谱分离测定了１５种氨基酸。采用含１０ｍｍｏｌ／Ｌ ｐＨ５．０的乙酸－乙酸钠缓冲溶液的甲醇－乙酸乙酯－水（１０／２／８８,Ｖ／Ｖ／Ｖ）溶液为流动相体系。分离测定了７种氨基酸;用甲醇－乙酸乙酯－水（２６／２／７７,Ｖ／Ｖ／Ｖ）分离测定了５种氨基酸;用甲醇－乙酸乙酯－水（４５／２／５３,Ｖ／Ｖ／Ｖ）分离测定了３种氨基酸。     

用自动滴定微库仑计分别测定混合物中半胱氨酸及胱氨酸的含量

半胱氨酸和胱氨酸在医药上有多种用途,能治疗多种疾病,又可供生物化学和营养学的研究之用。我们已用库仑滴定法分别测定了半胱氨酸和胱氨酸。国外已有用库仑滴定法分别测定混合物中半胱氨酸和胱氨酸含量的报导;也有用选择电流库仑法分别测出半胱氨酸、胱氨酸和蛋氨酸的报导。用自动滴定微库仑计在混合物中分别测定半胱氨酸和胱氨酸的研究是一种探索。本文利用在水溶液中溴能氧化半胱氨酸和胱氨酸,而碘只能氧化半胱氨     

非水库仑滴定法测定天然水体中溶解的无机碳

介绍用非水库仑滴定法测定天然水体中溶解的无机碳，对非水库仑滴定方法的关键技术－非水电解液进行了组分选择及优化，并对实验条件进行了优化。用该方法对碳酸钠标准溶液进行测定，测定结果的相对标准偏差为0.18%，测定值与理论值的平均相对误差为0.48%，表明该方法具有较高的精密度与准确度。     

基于K_3[Fe(CN)_6]选择性氧化自动电位滴定法同时测定药剂中半胱氨酸和胱氨酸

正目前常见的测定半胱氨酸(CySH)和胱氨酸(CySSCy)的方法有容量分析法~([1])、光度分析法~([2])和微库仑滴定法~([3])等。受药剂本身浊度的影响,容量分析法和比色法干扰严重;微库仑滴定法可实现二者同时测定,但所用滴定剂碘和溴具有挥发性和腐蚀性,给实际分析工作带来不便。电位滴定法同时测定半胱氨酸和胱氨酸虽有文献报道~([4]),但以汞离子作滴定剂,安全性受到质疑,且除杂程序繁琐。     

在混合表面活性剂存在下二溴邻硝基苯基荧光酮吸光光度法 …

在ＰＨ６．４的柠檬酸－Ｎａ２ＨＰＯ４缓冲介质中,Ｖ（Ｖ）与二溴邻硝基苯基荧光酮和ＣＰＢ反应生成红色多元配合物,建立了吸光光度测定微量钒的方法。配合物最大吸收波长为５９５ｎｍ,表观摩尔吸光系数为６．５×１０＾４,钒量在０～２０μｇ／２５ｍｌ内符合比耳定律。经测定配合物组成比为Ｖ（Ｖ）：ＤＢ０－ＮＰＦ;ＣＰＢ－１：４：４。采用ＭＩＢＫ溶剂萃取使钒与干扰元素分离后,方法用于合金钢中微量钒的测定,回收率为     

库仑滴定法测定对乙酰氨基酚

１引言中国药典（二部）１９９５年版推荐的对乙酰氨基酚（扑热息痛）的测定方法为紫外分光光度法。我们根据其易与Ｂｒ２发生取代反应的结构特点，采用库仑滴定法以电生溴为滴定剂方法反应速度快，电流效率容易达到１００％。用两个极化电极的电流法，即死停终点法指示终点。用于扑热息痛片剂样品的分析取得了满意结果。２实验部分２．１仪器与试剂ＫＬＴ－１型通用库仑仪（江苏分析仪器厂）；微量进样器（上海医用激光仪器厂）；比色管。对乙酰氨基酚对照品（含量≥９７．０％，中国药品生物制品检定所）；扑热息痛片剂（北京第四制药厂）…     

Robust flow-batch coulometric/biamperometric titration system: determination of bromine index and bromine number of petrochemicals

A flow–batch system was constructed and evaluated to perform coulometric titrations with biamperometric end point detection. The flow section of the system is employed for sampling by injecting a sample volume (50–300 μL) in a flow injection-like system. About 1.5 mL of a suitable carrier solution is delivered by a peristaltic pump in order to quantitatively transfer the sample to the system titration cell (2.0 mL total inner volume). The carrier contains the coulometric precursor for the titrant species. The cell contains two pairs of platinum electrodes used for coulometric generation of reagent and biamperometric detection and is actively stirred. The titrant species is generated and the titration is performed by the usual batch procedure with the excess of titrant being detected by biamperometry following the analysis of the titration curve. System operation is computer controlled and all operations are automated, including titration curve analysis and cell cleaning after the titration is ended. The system is characterized by its robustness because its operation does not depend on flow rates, and the work using coulometric methods which generate gases at the counter-electrode is not troublesome. The flow–batch system has been evaluated for determination of bromine index and bromine number (relative to the total reactive olefin content) in petrochemicals according to an ASTM procedure. Typical precision (R.S.D.) is between 0.5 and 6% for different petrochemicals whose bromine number/index vary from 1000 to 10 mg of bromine per 100 g of sample, respectively. Recoveries for standard additions are between 92 and 123% for 10 mg of Br₂ per 100 g increments and 98 to 101% for 100 mg per 100 g increments. Accuracy of the proposed system was evaluated against results obtained by the standard ASTM with no significant difference detected at 95% confidence level.     

A general method for coulometric titration of alkylphenols with bromine

A general method for coulometric titration of alkylphenols with anodically generated bromine is described. The reaction is carried out in a water-acetic acid medium and the reactivity is governed by varying the water content and the concentration of bromide ion and by the addition of pyridine. In that way all types of alkylphenols can be titrated quantitatively. For phenols containing more than one free ortho and para position, the titration can also be carried out either to the monobromination stage or to the full bromination stage. The mean relative error is ± 1·2% for monobromination and ±1·5% for full bromination. A method for rapid determination of the number of free ortho and para positions in alkylphenols by using two coulometric titrations is also described.     

Bromine number determination by coulometric flow-injection titration

The bromine number, the number of grams of bromine which react with 100 grams of a substance under given conditions, is a widely used parameter in the chemical and petroleum industries. A method of performing the bromine number determination by coulometric flow-injection titration, using both sequential injection with sinusoidal flow and single zone techniques, is described. Titrations of olefins, known interfering compounds, and petroleum distillates were performed and compared with the results of conventional bromine number titrations. Analyses yielded a relative standard deviation of 2%. Results compared favorably with those obtained by the conventional method for both pure (97%) olefins and petroleum distillates. The method was found to be insensitive to interference from nitrogen compounds. The CFIT technique combines the advantages of coulometric titrations: controlled generation of reagent, avoidance of reagent standardization requirements and reagent storage and stability problems; with the advantages of FIA: small volume requirements which reduce cost and waste, controllable dilution through flow programming, toxic materials contained within a closed environment, and the capability of being automated.     

Analysis of some electrochemical processes related to coulometric titrations at constant current

By considering the equilibrium potentials for the various electrode reactions which may occur in a coulometric titration, it is possible in certain cases to shorten the experimental exploratory work involved in the development of a new titration. The titration of trivalent arsenic by generated bromine and of dichromate by generated monovalent copper are treated as examples. Possible consequences of the irreversibility of electrode processes are examined. An analysis of the stability of the various chloro-complexes of mono- and di-valent copper is made in connection with the study of coulometric titrations involving generated monovalent copper     

Coulometric determination of sulfur-containing amino acids using halogens as oxidizing titrants

It is found that cysteine and methionine quantitatively react with electrogenerated halogens under the conditions of galvanostatic coulometry. Cysteine reacts with all titrants, and methionine reacts only with chlorine and bromine. The stoichiometric coefficients of reactions between cysteine and halogens are 1:3, 1:3, and 1:1 for chlorine, bromine, and iodine, respectively. These coefficients for methionine reactions with chlorine and bromine are 1:2 and 1:1, respectively. It is shown that cysteine can be selectively determined in its mixtures with methionine by coulometric titration with electrogenerated iodine. It is found that twofold amounts of methionine do not interfere with the determination of cysteine. A procedure is developed for the direct coulometric determination of methionine in tablets with a relative standard deviation of 3–5%.     

Galvanostatic Coulometric Determination of Salicylic Acid and Some of Its Derivatives Using Electrogenerated Halogens

Reactions of electrogenerated bromine and chlorine with salicylic acid and some of its derivatives were studied. Procedures for the galvanostatic coulometric determination of 2.4 to 19.2 g/mL of salicylic, acetylsalicylic, para-aminosalicylic acids and mesalazine in model solutions and medicinal preparations with electrogenerated halogens were developed (RSD varied from 1 to 5%). The end-point of coulometric titration was determined amperometrically with two polarized platinum electrodes.     

Coulometric titration with air transported sample

Air transported samples of a mixture containing the analyte and a supporting electrolyte are consecutively propelled into a microconduit system through a titration cell, a coil and a detector cell. Different amounts of electrochemically generated titrant are obtained in the separate samples while they are passing through the titration cell. Various quantities of the titrant are achieved by changing the duration of the titrant generating process that is done by various time for the sample solution staying in the titration cell (different sample movement rate). The titrated sample is then homogenised in the coil and detected in an electrochemical detector cell that supplies necessary data for the analyte determination. The declared method is experimentally verified on coulometric titration of hydrochloric acid (HCl) with electrogenerated sodium hydroxide and a titration of aniline with bromine generated in a bromide solution.