两点电位滴定法测定盐酸曲马多含量

1　引　　言盐酸曲马多是一种安全高效、无成隐性的新型镇痛药 ,目前我国药典还未收录。对其含量的测定 ,我国卫生部推荐用高效液相色谱法。作者根据盐酸曲马多药物中含有可电离卤素的特点 ,提出一种测定盐酸曲马多含量的新方法———两点电位滴定法。该法只需在滴定计量点前附近记录两次标准溶液体积和相应电极电位值 ,利用公式计算滴定计量点 ,即可确定盐酸曲马多含量。方法简便易行 ,测定结果与传统电位滴定法一致 ,是一种测定盐酸曲马多含量的简便实用方法。2　实验部分2 1　仪器与试剂　ｐＨＳ 3Ａ数字型酸度计 (厦门第二分析仪器厂 )…     

极弱酸碱的直接电位滴定

讨论了用两点电位滴定法直接测定pKn(或pKb)在10左右的极弱酸碱的可行性。该法只需在计量点后适当位置测定两组滴定数据，即可确定滴定计量点。与线性电位滴定法比较，两者结果一致。     

两点电位滴定法及其应用

提出了只需两组数据即可计算电位滴定计量点的电位滴定数据处理新方法－两点法，并在此理论基础上，提出了两点电位测定法。该法只需记录两次电极电位值和相应滴定剂体积，利用公式即可计算滴定化学计量点。详细讨论了各因素对方法准确度的影响，给出了衡量滴定进行程度的客观指标，为两点位置的选择提供了充分的理论依据。实验结果表明：该法操作方便，数据处理简单，精密度与准确度均较高，分析速度较经典电位滴定法有较大提高。     

强碱滴定一元弱酸突跃范围的计算

针对现有教材及文献对弱酸滴定计量点附近某些不甚合理的简化处理过程以及某些值得商榷的结论,根据滴定弱酸计量点附近溶液的实际组成,推导了合理的、适用任何情况的强碱滴定一元弱酸的突跃范围计算公式,从而给出了一元弱酸被准确滴定的判据。     

同时求出酸浓度和质子化常数的一元酸线性滴定法

利用一元酸的滴定计算式，线性回归同时求出酸浓度与质子比常数，实验只需等步长电位滴定化学计量点前约５个点。测定包括Ｋ＝１０＾１２的Ｈ２Ｏ２等１１种酸，得到了满意结果。本法有较大的应用价值。     

两点电位滴定法在非水滴定中的应用

硝酸舍他康唑主要用于治疗浅表性真菌新药,加巴喷丁是近20年来开发出能增强神经抑制和构思,控制神经兴奋的新一代抗癫痫药物,目前广泛应用于难治性癫痫等病历[1]。两种药物含量测定方法为高氯酸非水电位滴定。传统电位滴定法需要以较小的滴定体积间隔测定大量的滴定数据,数据处理比较繁琐,给实际应用带来诸多不便。在前人研究基础上,提出了识别电位滴定终点的方法并进行了实际应用[2-4]。依据该法,只需在滴定计量点前附近记录两次标准溶液体积和相应电极电位值,利用公式即可计算化学计量点。经对硝酸舍他康唑与加巴喷丁测定,方法精密度与准…     

氧化还原滴定计算新思路

提出一种计算氧化还原滴定的新思路.该思路根据电子守恒原则,提出了电子条件式的概念和书写方法.利用该法可一步写出氧化还原滴定计量关系式,且所得计算式容易从化学的角度来理解.     

高聚合物含量丙烯酸酯超微胶乳的制备

通过对一次加料法、单体预乳化法及单体两段滴加法制备超微胶乳的比较,发现单体两段滴加法的反应过程相当稳定.单体两段滴加法中,当预加单体量小于30%时,聚合过程稳定,氨化剪切后超微胶乳透光率约65%;当聚合物含量超过34%时,超微胶乳体系呈凝胶状.对胶乳的氨化剪切过程进行优化,发现加氨量有一最佳值,此时超微胶乳既保持较高的透光率 (～65%),又具有较低的粘度 (～220cp).最后,通过"单体两段滴加法乳液聚合 氨化剪切"制备了聚合物含量约为32%、乳化剂含量约为1.2%、数均粒径约为63nm、粒径分布为1.17的丙烯酸酯超微胶乳.     

一种新型光度探头的研制及铁的自动光度滴定

光度滴定不但能滴定常量物质,而且也能准确滴定浓度<1×10~(-5)mol·L~(-1)的微量物质.但目前光度滴定的应用还不很广泛,其主要原因在于,光度滴定计量点的判断一般要借助于分光光度计、液体循环池,并由绘制滴定曲线求得,相当麻烦.我们利用最大透光度570～600nm的黄色滤光片、小钨灯、光敏二极管,制成了一种高灵敏度的光度探头.配合MX-5型多功能化学分析仪,实现了自动光度滴定,并用于铁的测定取得了满意的效果.1 主要仪器与试剂     

对甲氧基苯辛基二甲基烯丙基氯化铵与丙烯酰胺共聚动力学研究

采用定时取样研究了以过硫酸钾-亚硫酸氢钠为引发剂,对甲氧基苯辛基二甲基烯丙基氯化铵(ADMAAC)和丙烯酰胺(AM)在水溶液中的共聚反应动力学,测定了相应的聚合速率方程、聚合表观活化能;采用阴阳离子相互作用测定残余ADMAAC的含量,紫外分光光度法测定残余AM的含量,根据单体投料量和残余量差值,得到低转化率下共聚物的组成,按Kelem-Tudos法得到两单体竞聚率。实验结果表明:聚合反应温度在40℃下,聚合速率方程为:Rp=K[M]1.241[KPS]0.52[SHS]0.55;根据Arrhenius经验公式计算出对甲氧基苯辛基二甲基烯丙基氯化铵(ADMAAC)和丙烯酰胺(AM)共聚的表观活化能为73.85kJ/mol,高于AM水溶液均聚合的活化能Ea(70.32kJ/mol);两种单体的竞聚率为rADMAAC=0.197、rAM=4.503,为ADMAAC-AM共聚合反应控制确定了重要的动力学参数。两单体的竞聚率的积小于1,ADMAAC与AM共聚合行为类型是一种无恒比点的非理想共聚行为,共聚物组成曲线,在对角线下方。     

药典中聚维酮碘测定方法的改进

提出了用两点电位滴定法测定聚维酮碘的新方法，该法只需在终点附近记录两次滴定数据即可计算滴定的化学计量点，分析速度较原药典法提高数十倍。     

Potentiometric titration of plutonium

In the potentiometric titration of plutonium(III), it has been customary to take the equivalence point as the inflection point on a plot of potential vs. volume of titrant.¹ That the stoichiometric end point corresponds to the inflection point does not seem to have been theoretically demonstrated, however. The purpose of this letter is to suggest that these points may not correspond in the potentiometric titration of plutonium(III). Mound Laboratory is operated by Monsanto Research Corporation for USERDA under contract No. EY-76-C-04-0053.     

再论滴定分析终点误差的统一计算

终点误差是高等分析化学课程的重要内容。当前分析化学教材多采用浓度定义式,并在此基础上推导出各种计算式。这种"公式化"的策略简单方便,但是没有实现统一计算,记忆负担重,而且难以解决复杂问题。本文从理论上证明了体积定义式完全等价于浓度定义式,从而为通过体积定义式统一计算终点误差提供支持,同时消除对体积定义式的误解。结果表明,体积定义式具有适用范围广、记忆负担轻、以及运算强度低的优点,能够统一四大滴定的终点误差计算。此外,对现行教材中的终点误差计算策略进行了梳理和归纳,剖析了现状,讨论了林邦公式在终点误差统一计算方面的缺陷,为相关研究提供参考。     

Redox Titrations-II Location of inflection points of titration curves for homogeneous redox reactions

The relative positions of the inflection points and equivalence point of a homogeneous redox reaction have been studied by using the redox buffer capacity to derive an equation for the titration curve. The position of the inflection point corresponding to the maximum slope of the titration curve relative to the equivalence point depends on the electron transfers of the analyte and the titrant (the stoichiometric coefficients of the reaction equation) and on the difference between the formal potentials of the redox couples in a more complicated way than has been described previously.     

利用滴定曲线方程和Origin精确绘制滴定曲线*

滴定曲线是滴定分析原理的重要内容。它显示了滴定过程中平衡体系性质的变化,可以获知化学计量点和滴定突跃信息,从而指导准确滴定判别或指示剂的选择。滴定曲线方程是滴定过程中体系的某种性质X(例pH)与滴定分数a(或滴定剂体积V)的关系方程,解析方程可获得函数X=f(a)的表达式。对一些较复杂的体系,推导函数X=f(a)较困难,但多数情况下反函数a=g(X)的推导更容易,表达式也更简洁。本文对酸碱、配位、氧化还原和沉淀滴定曲线方程进行了系统总结,并对不同情况下的函数X=f(a)或反函数a=g(X)进行了推导,拓展了教材内容。根据函数关系,在Origin中利用其函数绘图功能可直接绘制出滴定曲线,不用先生成数据点再绘图,方便快捷。用反函数绘图时增加数据点即可获得高精度的滴定曲线,可直接从滴定曲线上查找化学计量点和滴定突跃信息。     

高精度散射光度滴定法测定诺氟沙星的含量

用四苯硼钠标准溶液作滴定剂,采用高精度散射光度滴定法测定了诺氟沙星的含量,并将测定结果与非水滴定法、非水电位滴定法和高效液相色谱法的测定结果进行比较。结果表明：用本方法测定诺氟沙星的含量具有较高的准确度、精密度和良好的线性,且不受其降解产物的干扰。     

Development of algorithms for automated spectrophotometric titrations

A versatile method for evaluation of equilibrium constants from automated spectrophotometric titrations is described. General algorithms were derived for normalized titration curves of reactions having various stoichiometric ratios. Normalization of data involve converting it from absorption versus time to product formed (0 to 1) versus equivalents of titrant added. Relevance of derived algorithms was assessed by the quality of their fit to real data. The demonstration system chosen for this investigation was the 1:3 complexation reaction of Fe(II) and 1,10-phenantroline (o-Phen). Titrations were performed at three distinct infusion rates under controlled pH of 5.0 and at 25.0 °C, with sets produced using both Fe(II) and o-Phen as the titrant. Direct fitting of titration curves yielded values for overall equilibrium constants. Furthermore, resulting curves revealed reproducible initial deviation, consistent with step-wise reaction, when titrating Fe(II) with o-Phen. No unusual deviations were evident anywhere in the titration curves when Fe(II) was the titrant. Overall, our approach facilitates adoption of automated titrimetry and data analysis methodologies for the determination of stoichiometries and equilibrium constants of many UV/Vis active reactions.     

Polyelectrolyte titration using fluorescent indicator. I. Direct titration of anionic and cationic polyelectrolytes with 10−4N standard solutions

The polyelectrolyte titration, which was originally called colloid titration, is based on the stoichiometric reaction between positively charged colloidal particles and negatively charged ones. In the conventional method, the metachromatic color change of the indicator, toluidine blue, from blue to red-purple has been applied for the determination of the end point in the titration. 2.5 × 10^?3N potassium polyvinylsulfonate (KPVS) is usually used as the standard titrant. In this work, fluorescent indicators such as 6-(p-toluidino)-2-naphthalene sulfonate (TNS), acridine orange, etc., have been introduced. The fluorescence intensity was measured using the spectrophotometer equipped with magnetic stirrer and connected with a vinyl tube attached to the hand piston burette. For example, TNS is practically nonfluorescent, but it exhibits strong fluorescence when it is bound to a cationic polyelectrolyte (CP). The fluorescence of the TNS–CP complex is diminished by titration with KPVS standard solution since TNS is liberated from the complex by substitution with KPVS. After the equivalent point, the fluorescence intensity becomes constant and the end point can thus be detected by that point. It has been elucidated that the very dilute standard solution like 1 × 10^?4N can be used because the sensitivity of fluorescence detection is extremely high. © 1993 John Wiley & Sons, Inc.