Conductometric and potentiometric investigations of ionic surfactant– gelatin interaction

 The interaction between gelatin and ionic surfactant is relevant to many biological and industrial processes. Therefore, knowledge of the mechanism of ionic surfactant–gelatin interaction is an important factor influencing practical application of such systems. In this paper, conductometric and potentiometric titrations were used to study the interaction of sodium dodecyl sulfate as an anionic and cetyltrimethylammonium bromide as a cationic surfactant with gelatin solutions of different concentrations. Titrations were carried out at 40 °C by adding surfactant to the gelatin solutions. The titration course was followed by measuring specific conductance and pH changes. On the basis of the titration curves the prevailing mechanisms of surfactant–gelatin interaction, as well as the characteristic concentrations at which they are changed, were determined. From the linear relationship established between the characteristic surfactant concentrations and gelatin concentration, maximal amount of surfactant bonded per gram of gelatin was calculated. Received: 22 July 1997 Accepted: 11 December 1997     

Microcalorimetric Study on the Oscillating System of Two-phase Reaction of Aqueous Acid with Primary Amine in Chloroform

It has been found that the two-phase reactions of aqueous HCl,HOAc or H3PO4 with primary amine N1923 in chloroform are osiclating reactions.Their power-time curves were measured by the titration microcalorimetric method,and the induction period(tin).The first oscillating period(tp.1) and the second oscillating period (tp.2) were determined.The apparent activating parameters and the orders of the oscillating systems were calculated and the following relationships were established:for the oscillating system of hydrochloric acid.     

电容滴定法测定自组装膜表面酸度

利用本实验室自制的电容法时测量装置对巯基丙酸自组装膜的表面酸度进行电容滴定研究，相对于先前的测量和滴定技术。本方法可同时对界面电容值和溶液的PH值进行实时测定。同时对影响电容测定和自组装膜表面pKa值的各种因素进行了详细的讨论。 滴定结果和文献报道相近，证明了测定方法和仪器的可靠性实用性。     

杯芳烃的配位化学——Ⅶ.水溶性杯［8］芳烃与过渡元素配合物的热力学研究

本文首次报道了八对磺酸钠八羟基羰基甲氧基杯［8］芳烃酸离解常数的测定结果，还以pH滴定法对该试剂与过渡元素的各种配合物进行系统研究，发现此配体能形成MHnL(n=1-7)型配合物。     

固定pH法测定两组分极弱酸（碱）混合体系

将固定pH滴定法结合求解一元线性回归方程组应用于极弱酸(碱)混合体系中各组分含量的同时测定。测定了六次甲基四胺-硫酸钠和六次甲基四胺-乙酸钠混合体系中各组分的含量,回收率为96.7％～103.2％。     

A new reductimetric reagent: Iron (II) in acetic acid medium and in presence of pyrophosphate. Spectrophotometric titration of some oxazine dyes

Iron(II) in acetic acid medium and the presence of pyrophosphate is used as a new reductimetric reagent and utilised for the spectrophotometric titration of microgram quantities of six oxazine dyes. All these dyes are rapidly and quantitatively reduced to their colourless leuco-bases in a 2-electron reduction with iron(II), provided the medium contains 1 or 3M acetic acid (depending on the dye) and at least 0.1M pyrophosphate. The redox potentials of the iron(III)/iron(II) couple at different pyrophosphate and acetic acid concentrations have been measured and a method for purification of some of the commercially impure oxazine dyes is suggested.     

5-氟尿嘧啶与牛血清白蛋白的相互作用

根据合理的假设和Langmuir结合理论, 在298.15 K下, 以等温滴定微量热(ITC)实验数据为依据, 应用非线性最小方差拟合方法确定了抗肿瘤药物配5-氟尿嘧啶(5-FU)与牛血清白蛋白(BSA)相互作用的热力学性质的改变. 研究结果表明, 牛血清白蛋白(BSA)与5-氟尿嘧啶相互作用存在两类结合位点. 第一类结合, N=(54.0 0.3), ⊿H⁰=(30.0±0.4) kJ·mol^-1 (吸热), ⊿S⁰=(196.0±2.6) J·mol-1·K-1(熵增), ⊿G⁰=(-28.4±0.3) kJ·mol^-1; 第二类结合, N=(77.0±0.4), ⊿H⁰=(-20.0±0.4) kJ·mol^-1 (放热), ⊿S⁰=(28.6±0.3) J·mol^-1·K^-1 (熵增), ⊿G⁰=(-28.5±0.2) kJ·mol^-1. 结合体系的圆二色谱(CD)分析结果说明, 抗肿瘤药物5-氟尿嘧啶与BSA的相互作用诱导蛋白质(BSA)二级结构单元的相对含量发生了一定程度的变化.     

Binary and Ternary Complexes Between Lauryl Hexaoxyethylene, Benzoate and Cyclodextrin. Part I. α-CD

The characterization of binary and ternary complexes of benzoate, lauryl hexaoxyethylene (C₁₂E₆) and -CD is presented. Complexation was characterized by capillary zone electrophoresis and titration microcalorimetry. These techniques suggested that -CD formed two qualitatively different complexes with C₁₂E₆. The stoichiometric ratio of -CD : C₁₂E₆ in the individual complexes was 1 : 1 and 1.4 : 1, with stability constants of2.0 × 10³ M^-1 and 6.4 × 10⁵ M^-1.4, respectively. At higher concentrations of interacting species (10 mM), a precipitate formed. Addition of benzoate seemed to prevent precipitate formation and appeared to increase the stability constants of both binary complexes. Both techniques also indicated formation of ternary complexes between -CD, C₁₂E₆ and benzoate.     

铜铁试剂的交流示波极谱滴定法研究

提出了用交流示波极谱滴定法测定铜合金中的铜和测定铜铁试剂的方法。该法快速、准确、终点直观。测定了铜合金中的铜,变动系数0.07％～0.17％。考察了紫外光照射下铜铁试剂的动力学行为。