毛细滴管数滴微型滴定法野外快速测定水中溶解氧

用毛细滴管数滴微型滴定法对水中溶解氧进行了现场快速测定。实验结果表明,该法的不确定度Urel(C)约为1.6%,与常量滴定法相当,符合国家标准。该法以自制的液滴体积为0.01~0.02 mL的聚乙烯毛细滴管就地进行滴定,避免了水样长期保存和运输中产生的误差。其主要仪器外形小巧、便于携带,滴定快速、准确,滴定剂用量仅为65~100滴,完全能够满足现场快速水质测定和野外水环境监测的需要。     

毛细滴管数滴法测定水中硫酸根含量

以自制的液滴体积为0．01—0．02mL的聚乙烯毛细滴管对水中硫酸根离子含量进行数滴分析,其主要仪器外形小巧、便于携带,滴定快速、准确,试剂消耗量约为常量法的5％,滴定剂用量约为50—200滴。该法的优点是仪器携带方便,适用于水中硫酸根离子含量的室外快速分析。     

毛细滴管-电子天平微型称量滴定法测定天然石膏中的碳酸盐含量

以液滴质量约为0.005~0.01 g的聚乙烯塑料毛细滴管和电子天平代替普通称量滴定装置进行微型滴定,不仅减轻了热胀冷缩、量器误差和人为操作等因素带来的不利影响,也简化了实验装置和操作技术,减少了试剂用量,使测定过程更方便、快速,从而建立了一种毛细滴管-电子天平微型称量滴定法分析新方法。采用该法测定天然石膏中的碳酸盐含量,当滴定剂用量为0.5~1.0 g时,相对标准偏差在0.38%~0.66%范围,优于常量法,可以推广应用。     

水中硫酸根及其总硬度的EDTA滴定法——采用计滴微型毛细管滴定管

用EDTA微量滴定法测定了水中硫酸根及总硬度,测定过程在氨性缓冲介质中进行,采用络黑T作指示剂,用一种自制的聚乙烯微型毛细管滴定管进行滴定,滴定反应所耗的滴定剂用计滴法计数。从微滴管流出的每一小滴滴定剂的体积（通常在0．01～0．02mL之间）用重量法校正,每次滴定所耗滴定剂一般在50～200小滴之间。此方法的扩展不确定度,对硫酸根测定为0．94％与重量法相当,而精密度则优于重量法,对总硬度测定为0．82％优于常量滴定法。此方法的特点为分析快速、准确,消耗试剂少且便于携带,适合于现场或野外分析应用。     

零流电位法在酸碱滴定中的应用研究

探讨了零流电位法在酸碱滴定中的检测原理及应用,通过考察强碱滴定弱酸、强碱滴定强酸、强酸滴定弱碱以及强酸滴定强碱四种滴定体系,探明了零流电位法在酸碱滴定中的适用性。通过氢氧化钠滴定醋酸对本方法进行评价,实验结果表明:本法的相对误差为-0.4%,同一根电极的滴定值的相对标准偏差(RSD)为0.4%(n=5),同一根电极五天滴定值的RSD为0.6%,五根电极滴定值的RSD为0.5%。本方法具有较高的准确性、稳定性和重现性。     

毛细滴管在计滴微量滴定法中的应用及其测量不确定度的评定

与不锈钢及玻璃相比,聚乙烯是制作毛细管微滴定管的合适材料。所制成的微滴定管应用于计滴微量滴定法中,并通过食醋中总酸度的测定,食盐中碘酸盐的测定,水的总硬度测定及水中溶解氧的测定等4种方法中的应用对其适用性作了考核,对计滴微量滴定法测定食醋的总酸度的测量不确定度作了评定。如试验数据所示,从微滴定管流出的滴定剂每滴的体积在0.01～0.02 mL之间。如果一次滴定所耗滴定剂总量在70～110滴（约1 mL）之间,上述4种测定方法所得结果的RSD值（n=6）在0.6%～1.8%之间,回收率试验的结果在99.4%～101.4%之间,食醋中总酸度测定的扩展相对不确定度评定为1.0%。此外,与常规的常量滴定法相比,用毛细滴管的计滴微量滴定法具有等同的准确度和精密度,而在方便携带,成本低廉及操作简便、快速等方面却大大优于前者。     

滴体积测表面张力实验中滴管口径的逼近求法

滴体积法测表面张力实验中 ,滴管口半径一般由显微装置测量 ,本文提出了一种应用计算机逼近计算求滴管口半径的方法。     

多元校正双指示电极电位沉淀滴定法同时测定混合卤素离子

建立一种可同时测定混合卤素离子的电位滴定新方法.在这种方法中,滴定剂是硝酸银和氟化钠的混合溶液,被滴定液中同时插入了氟离子指示电极和银离子指示电极.在滴定过程中的任一滴定点,溶液中Ag 的浓度和滴定剂的加入体积可由两个电极的电位测定值同时获得,从而可应用多元校正法由相应的滴定曲线求得混合卤素离子中每一种离子的含量.用该方法对混合物样品中的Cl-、Br-、I-进行了同时测定,测定结果的相对标准偏差为0.13%～0.45%(n=5),回收率为97.3%～103.4%.     

液／液界面毛细管电极的不对称扫描循环伏安法研究

最近,对电荷在微毛细滴管尖端的液/液界面转移的电化学过程进行了研究。这些研究中,将互不相溶的两种电解质溶液之一充入微毛细滴管中,当它的细端浸入另一相溶液中     

航空润滑油酸植的测定

酸值是航空发动机润滑系统的一项重要指示 ,根据酸值的大小可以判断使用中润滑油的变质程度 ,对航空发动机运转状况进行动态监测 ,以便人们更换油料 ,从而保证机器不会由于油的原因而发生故障、损坏。酸值的测定 ,一般采用酸碱滴定法 ,即指示剂法和电位法判断终点 [1～ 4]。指示剂法是用中和乙醇为滴定溶剂 ,甲酚红作指示剂 ,用已知浓度的氢氧化钾乙醇溶液滴定 ,通过颜色的改变来指示终点 ;电位法则是用甲苯、水和异丙醇混合液作滴定溶剂 ,滴加已知浓度的氢氧化钾异丙醇溶液 ,以电位计读数对滴加体积作图 ,取曲线的突跃点为滴定终点。在测定…     

A new oxidimetric reagent: potassium dichromate in a strong phosphoric acid medium--VII. Photometric titration of vanadium(IV) and of cerium(III) alone and in mixtures with iroN(II)

Vanadium(IV) can be accurately titrated with potassium dichromate in media containing phosphoric acid of 3-12M concentration: the change in absorption of vanadium(IV) is followed in the region 660 mmicro using a red filter. It is more convenient to carry out the titration in 3M phosphoric acid because at higher concentrations chloride, nitrate, cerium(III) and manganese(II) may interfere. Photoelcetric titration is more convenient than potentiometric because the former can be made in a 3M phosphoric acid medium, whereas the latter is possible only in 12M phosphoric acid. The simultaneous differential photometric titration of iron(II) and vanadium(IV) is also possible. Conditions have been found for the photometric titration of cerium(III) and of cerium(III) plus iron(II). The titration is carried out (at 450 mmicro or with a blue filter) in about 10.5M phosphoric acid. Application of the method to a cerium mineral is considered.     

毛细管电泳高频电导检测器的研制

设计了一种新的毛细管电泳检测器.根据高频电导滴定原理,将电导电极做成两个金属圆筒套于分离毛细管外,并向两个电极施加高频电压.经毛细管分离后的组分流过两个电极之间时,高频电流发生变化,得到毛细管电泳图.该检测器具有应用范围广、操作简便及重现性好等优点,已初步应用于混合无机离子的测定.     

New Isothermal Titration Calorimeter for Investigations on Very Small Samples. Theoretical and experimental studies

A new isothermal titration calorimeter with 78.5 μL volume capillary chambers has been developed. It is based on the theory of mixing reagents in a capillary chamber of a titration calorimeter and separation of the sensitive volume of chambers in a differential calorimeter. The evaluation of the efficiency of diffusion mixing is described by means of an oscillating dispensing needle. The calorimeter was tested by the reactions: Ba²⁺– 18-Crown-6 and Rnase-2’CMP. The main advantages of the new titration calorimeter are the use of very small amounts of reagents, the high accuracy of separating the sensitive volume of calorimetric chambers and the minimization of power input while mixing reagents in a horizontally located capillary chamber. This revised version was published online in August 2006 with corrections to the Cover Date.     

Studying dispersoid systems

Summary Measurements of energy transformation in mitochondria are done on a capillary differential titration calorimeter CTD2156. It is important to mention that a sediment is quickly formed by the mitochondria suspension without mixing by means of a vibrating needle. During the measurements, the vibrating needle is located inside the working volume of the chamber. The design of the calorimeter is substantiated theoretically. It provides a new mode of a reagent input in the measuring volume of the calorimetric chambers. It expands the spectrum of tasks that can be solved using this instrument. In the capillary calorimeter the calorimetric chambers unit is simple and small in size. These advantages of capillary chambers provide an opportunity to unite 20 capillary calorimetric chambers in one calorimetric block. It allows designing a multi-channel titration calorimeter. There are obvious advantages of such a calorimeter over other instruments in screening researches and in researches of objects maintaining stability only for a short time.     

Modulated capillary titration calorimeter

A modulated capillary titration calorimeter has been developed. New software and optimization of the calorimetric unit CTD2156 are used as a basis of the modulated capillary titration calorimeter. The scanning mode of the calorimeter has been theoretically substantiated. The scanning of chambers temperature is provided due to the fact that the shield temperature is linearly varied at heating and cooling. The reversing and kinetic part of the total heat flow are measured at heating of a diluted collagen solution. The main advantage of the calorimeter is its ability to operate in a modulation mode, in an isothermal mode, in modes of linear heating and cooling of homogeneous and dispersoid liquid samples at an effective mixing of reagents in calorimetric chambers.     

PVC膜电极上的示波电位滴定法及其在药物分析中的应用

本文研究了用于示波电位滴定的PVC膜电极,成功地用于中和、络合及沉淀滴定,并探讨了它们在药物分析中的应用。所研究电极见表1。实验部分一仪器与试剂 SR-071型双踪示波器,213型铂片电极     

Potentiometric titration in a low volume of solution for rapid assay of uranium: application to quantitative electro-reduction of uranium(VI)

A simple, inexpensive PC based potentiometric titration technique for the assay of uranium using low volumes of sample aliquot (25–100 μL) along with all reagents (total volume of solution being less than 2.5 mL) is presented. The technique involves modification of the well known Davies and Gray Method recommended for assay of uranium(VI) in nuclear materials by introducing an innovative potentiometric titration device with a mini cell developed in-house. After appropriate chemical conditioning the titration is completed within a couple of minutes with display of online titration plot showing the progress of titration. The first derivative plot generated immediately after titration provides information of end point. The main advantage of using this technique is to carry out titration with minimum volumes of sample and reagents generating minimum volume of wastes after titration. The validity of the technique was evaluated using standard certified samples. This technique was applied for assay of uranium in a typical sample collected from fuel reprocessing laboratory. Further, the present technique was deployed in investigating the optimum conditions for efficient in situ production of U(IV). The precision in the estimation of uranium is highly satisfactory (RSD less than 1.0%).     

Characterization of complexes between phenethylamine enantiomers and β‐cyclodextrin derivatives by capillary electrophoresis—Determination of binding constants and complex mobilities

To optimize chiral separation conditions and to improve the knowledge of enantioseparation, it is important to know the binding constants K between analytes and cyclodextrins and the electrophoretic mobilities of the temporarily formed analyte‐cyclodextrin‐complexes. K values for complexes between eight phenethylamine enantiomers, namely ephedrine, pseudoephedrine, methylephedrine and norephedrine, and four different β‐cyclodextrin derivatives were determined by affinity capillary electrophoresis. The binding constants were calculated from the electrophoretic mobility values of the phenethylamine enantiomers at increasing concentrations of cyclodextrins in running buffer. Three different linear plotting methods (x ‐reciprocal, y ‐reciprocal, double reciprocal) and nonlinear regression were used for the determination of binding constants with β‐cyclodextrin, (2‐hydroxypropyl)‐β‐cyclodextrin, methyl‐β‐cyclodextrin and 6‐O‐α‐maltosyl‐β‐cyclodextrin. The cyclodextrin concentration in a 50 mM phosphate buffer pH 3.0 was varied from 0 to 12 mM. To investigate the influence of the binding constant values on the enantioseparation the observed electrophoretic selectivities were compared with the obtained K values and the calculated enantiomer‐cyclodextrin‐complex mobilities. The different electrophoretic mobilities of the temporarily formed complexes were crucial factors for the migration order and enantioseparation of ephedrine derivatives. To verify the apparent binding constants determined by capillary electrophoresis, a titration process using ephedrine enantiomers and β‐cyclodextrin was carried out. Furthermore, the isothermal titration calorimetry measurements gave information about the thermal properties of the complexes.     

Contribution au microdosage titrimétrique de l'iode organique

Simultaneous microdetermination of carbon, hdrogen and iodine in organic substances is practically possible on a five milligramme sample. The two first mentioned elements are gravimetrically deetermined, iodine being titrated. The available results are quite good.New calibration technique of capillary instruments enables precise titration of very small quantities of Iodine. It will help to improve precision of this determination.