硫酸铵中氮含量的电位滴定检测

建立一种酸碱电位滴定法直接测定硫酸铵中氮含量的方法。样品溶解后,可直接用氢氧化钠标准滴定溶液进行滴定。为了保证检测的准确度,分别使用硫酸铵高纯试剂和邻苯二甲酸氢钾基准试剂对氢氧化钠标准滴定溶液进行标定,并对标定结果进行比较,两种方法基本无差异。同时,通过适量硫酸的加入避免了样品中游离硫酸对检测结果的影响。该方法检测速度快、检测精度高、绿色环保、易于控制,非常适合于硫酸铵中氮含量的检测。将本方法与蒸馏后滴定法(仲裁法)检测结果进行比较,两种方法无显著性差异。采用本方法测得氮含量的加标回收率为99.9 %-100.3 %,相对标准偏差(RSD,n=5)为0.03 %-0.05 %。分别使用实验方法和蒸馏后滴定法测定不同样品的氮含量,结果相吻合。     

电位滴定法测定抛光液中的三酸含量

探讨了利用自动电位滴定仪对抛光液中磷酸、硫酸及硝酸的分析方法,以及对溶剂的标定方法。电位滴定法测定三酸,先用硫酸亚铁铵滴定硝酸,再用氢氧化钠滴定磷酸和硫酸,从而计算三酸含量。结果表明,与传统滴定法相比,电位滴定法标定硫酸亚铁铵的相对标准偏差(RSD)从1.1%降至0.13%,标定氢氧化钠的RSD从0.72%降至0.06%。电位滴定法测定自配样品及工厂抛光产品中的硝酸,回收率分别在96%及93%以上。电位滴定法测定自配样品及工厂抛光产品中磷酸和硫酸的回收率偏差在3%以内。手动滴定法测定磷酸和硫酸的回收率偏差在5%~10%,回收效果不如电位滴定法。电位滴定法测定工厂抛光液的三酸加标回收率偏差均小于3%。自动电位滴定法比手工滴定的准确性和精密度明显提高,弥补了手工滴定法只能分析磷酸和硫酸,而无法测定硝酸的缺陷。     

电位滴定法测定抛光液中的三酸含量

探讨了利用自动电位滴定仪对抛光液中磷酸、硫酸及硝酸的分析方法,以及对溶剂的标定方法。电位滴定法测定三酸,先用硫酸亚铁铵滴定硝酸,再用氢氧化钠滴定磷酸和硫酸,从而计算三酸含量。结果表明,与传统滴定法相比,电位滴定法标定硫酸亚铁铵的相对标准偏差(RSD)从1.1%降至0.13%,标定氢氧化钠的RSD从0.72%降至0.06%。电位滴定法测定自配样品及工厂抛光产品中的硝酸,回收率分别在96%及93%以上。电位滴定法测定自配样品及工厂抛光产品中磷酸和硫酸的回收率偏差在3%以内。手动滴定法测定磷酸和硫酸的回收率偏差在5%～10%,回收效果不如电位滴定法。电位滴定法测定工厂抛光液的三酸加标回收率偏差均小于3%。自动电位滴定法比手工滴定的准确性和精密度明显提高,弥补了手工滴定法只能分析磷酸和硫酸,而无法测定硝酸的缺陷。     

表面活性剂碱度测定方法的改进和验证

表面活性剂碱度的检测主要依照国标GB/T 7378-1996中的方法,使用手动滴定、依据指示剂来判断滴定终点.本文基于全自动电位滴定仪对国标方法进行了改进和验证,建立了表面活性剂碱度测定的光度滴定法和电位滴定法,并对两种改进方法进行了验证.改进后的方法分别根据光度电极和电位电极的突跃点来判断滴定终点,判断更准确,与国标方法的结果相一致,重复性RSD≤3.0％.在国标方法基础上改进的光度滴定法和电位滴定法,滴定体积控制精确、自动化程度高、重复性和准确性好,可作为国标方法的改进方法用于实际检测.     

全自动电位滴定法测定锂电池原料碳酸锂中主成分的含量

采用全自动电位滴定法测定锂电池原料碳酸锂中主成分的含量,用盐酸标准溶液进行滴定,考虑自动电位滴定仪的灵敏性和准确度,通过多次对比实验,确定了仪器的最佳工作参数、滴定剂浓度和样品称样量等滴定条件;对两个不同品位试样分别进行了11次平行测定,相对标准偏差(RSD)均小于1%。在碳酸锂试样中加入基准物质无水碳酸钠进行碳酸根的加标回收实验,碳酸根的加标回收率在99.4%~100%。与传统的酸碱滴定法相比,全自动电位滴定法方便、快捷,同时方法测定结果准确、可靠、精密度高,适合大批量样品快速分析。     

全自动电位滴定法测定锂电池原料碳酸锂中碳酸锂的含量

采用全自动电位滴定法测定锂电池原料碳酸锂中碳酸锂的含量,用盐酸标准溶液进行滴定,考虑自动电位滴定仪的灵敏性和准确度,通过多次对比实验,确定了仪器的最佳工作参数、滴定剂浓度和样品称样量等滴定条件;对2个不同品味试样分别进行了11次平行测定,相对标准偏差（RSD）均小于 1%。在碳酸锂试样中加入基准物质无水碳酸钠进行碳酸根的加标回收实验,碳酸根的加标回收率在99.4%～100.2%之间。与传统的酸碱滴定法相比,全自动电位滴定法方便、快捷,同时该方法测定结果准确、可靠、精密度高,适合大批量快速分析样品。     

自动电位滴定法连续测定水中卤素离子

目前化验室滴定分析普遍采用指示剂滴定法检测水中卤素离子。由于指示剂受到人眼辨色能力、有色或浑浊样品影响较大,特别是对滴定平衡常数[1]较小(Ka/b<10-7),变色不敏锐,或者指示剂不够灵敏时,会造成一定的终点误差。电位滴定法克服了这些缺点,以测量待测溶液的电位突变来确定滴定终点。本文利用卤化银的Ksp差异,用自动电位滴定法连续测定Cl-、Br-I、-的含量。水样无须预处理,对有色、浑浊等水样可直接参与滴定分析。1试验部分1.1仪器808 DMP型自动电位滴定仪。1.2工作条件信号漂移值为30 mV·min-1,最小增液量为10μL,加液速率50 mV…     

计算滴定分析法的分类及其进展

提出了将计算滴定分析法分为控制体积滴定法和控制电位滴定法两个大类的观点。控制体积滴定法包括线性滴定法、单点滴定法及双点滴定法;控制电位滴定法包括控制单电位滴定法和控制多电位滴定法。本文介绍了两类计算滴定分析法的基本原理、方法特点、相互联系、引起误差的原因及其最新进展。     

自动电位滴定法测定高纯氯化铵的纯度

建立自动电位滴定法测定高纯试剂氯化铵纯度的方法。以硝酸银标准滴定溶液作滴定剂,采用自动电位滴定仪测定高纯氯化铵的含量。测定结果的相对标准偏差为0.03%(n=6)。采用该法与化学滴定法对高纯氯化铵样品进行测定,两种方法的测定结果无显著性差异。该方法操作简便、快捷,自动化程度高,滴定终点判断敏锐,测定结果准确可靠。     

加强电位滴定法实验课程的探讨

介绍了电位滴定的原理、分类及其在药品食品等检验行业的应用情况,电位滴定法具有操作方便、分析高效、数据准确等特点,应用范围极其广泛。鉴于电位滴定法的重要作用及广泛应用,在我国化学教育机构中,应该普及电位滴定仪,增加电位滴定实验课程,使学生更好地了解电位滴定仪,掌握先进分析技术。     

Untersuchungen über die Alkoholyse des SiS2. IX. Potentiometrische Titration der Trialkoxysilanthiole mit Silbernitrat

Potentiometric Titration of Trialkoxysilanethiols with Silver Nitrate The reaction of trialkoxysilanethiols and AgNO₃ in isopropanol-benzene solutions by means of potentiometric titration was investigated. This method is also suitable for analysis of silanethiols.     

New Ion‐Pair Based All‐Solid‐State Surfactant Sensitive Sensor for Potentiometric Determination of Cationic Surfactants

Cationic surfactants of different types were determined using a few potentiometric sensors based on ion‐pair complexes (dodecyldimethylbenzylammonium dodecylsulfate, dodecylmethylbenzylammonium dodecylbenzensulfonate, tetrahexadecylammonium dodecylsulfate and Hyamine (benzethonium dodecylsulfate)) as sensing materials. The response of the all‐solid state surfactant sensitive electrode based on a Teflonized graphite conducting substrate, coated with a PVC membrane containing sensing material, was investigated in the solutions of Hyamine and hexadecyltrimethylammonium ion in the concentration range from 1 μM to 10 mM. Potentiometric surfactant cation titration has been performed using sodium dodecylsulfate as titrant and an ion‐pair‐based surfactant sensitive electrode as a potentiometric indicator. Several commercial surfactant products have also been titrated and the results were compared with those obtained with two‐phase standard titration method.     

酸碱电位双点滴定法在药物分析中的应用

探讨酸碱电位双点滴定法在药物分析中的应用。提出测定药片中的盐酸麻黄碱和烟酸的实验方法及其实验参数。该法简便快速。对２种样品的测定结果令人满意。     

Selective preconcentration of uranyl ion by silica gel phases modified with chelating compounds as inorganic polymeric ion exchangers.

Four chemically modified chelating silica gel phases (I - IV) with ion exchange groups were tested for their potential capability to selectively bind, extract and preconcentrate uranyl ions (UO(2)(2+)) from different aqueous solutions as well as ore samples. Factors affecting such determination processes were studied and optimized. These included the pH of the contact solution, the mass of the silica gel phase extractant, the stirring time during the application of a static technique and the eluent concentration for desorption of the surface-bound uranyl ion and interfering anions and cations. All these factors were evaluated on the basis of determinations of the distribution coefficient value (K(d)) and the percent recovery (R%). Percent recovery values of 91% for silica phase (II) and 93% for silica phase (IV) were identified in the optimum conditions. The proposed preconcentration method was further applied to uranium ore samples as well as granite samples. The determined percentage and ppm values are in good agreement with the standard assigned ones. The structure of the synthesized silica gel phases (I - IV) and their uranyl bound complexes were identified and characterized by means of infrared analysis, thermal analysis (TGA) and potentiometric titration.     

Modified sensors based on semiconductor and metallic materials for the determination of cyan- and iodine-containing pesticides by potentiometric titration

Potentiometric sensors based on semiconductor and metallic materials modified by electrochemical techniques are proposed. It is demonstrated that the electrochemical modification of the surface improves the electroanalytical properties of the electrodes. Nonmodified and modified electrodes are recommended for the potentiometric titration of iodides. Procedures are developed for the potentiometric determination of cyanide- and iodine-containing pesticides using GaAs- and Ti-electrodes.     

Potentiometric determination of silver with dithiooxamide

Potentiometric titration with dithiooxamide solution can be used to determine silver in the 0.0100–50.0 p.p.m range with an average accuracy of ca. 0.5% and a relative standard deviation ranging from 1.26% to 0.03% The metals commonly associated with silver can be masked with fluoride and EDTA The advantages of the method over other potentiometric and common spectrophotometric methods are outlined.     

Zn-Al类水滑石结构正电荷对内禀电离平衡常数的影响

采用电势滴定(potentiometric titration,PT)法测定了Zn-Al类水滑石(HTlc)的零净电荷点(pHPZNC);利用电势滴定数据直接计算得到Zn-Al HTlc的内禀电离平衡常数(pKa2int)和质子吸附自由能(G0ads,2);研究了结构电荷密度(σp)对pKa2int 和G0ads,2的影响.结果表明,随σp增加, pKa2int 和G0ads,2数值均降低,说明σp越大,带正电荷的HTlc与H＋结合力越低,HTlc去质子能力越强,H＋游离出HTlc表面的趋势越大.研究发现，HTlc的pKa2int与pHPZNC之间符合关系式: pKa2int =1.372pHPZNC－3.328.     

Textile-based sampling for potentiometric determination of ions

Potentiometric sensing utilizing textile-based micro-volume sampling was applied and evaluated for the determination of clinically (Na⁺, K⁺, Cl^–) and environmentally (Cd²⁺, Pb²⁺ and pH) relevant analytes. In this technological design, calibration solutions and samples were absorbed into textiles while the potentiometric cells (ion-selective electrodes and reference electrode) were pressed against the textile. Once the liquid, by wicking action, reached the place where the potentiometric cell was pressed onto the textile, hence closing the electric circuit, the potentiometric response was obtained. Cotton, polyamide, polyester and their blends with elastane were applied for micro-volume sampling. The textiles were found to influence the determination of pH in environmental samples with pH close to neutral and Pb²⁺ at low analyte concentrations. On the other hand, textile-based micro-volume sampling was successfully applied in measurements of Na⁺ using solid-contact sodium-selective electrodes utilizing all the investigated textiles for sampling. It was found that in order to extend the application of textile-based sampling toward environmental analysis of ions it will be necessary to tailor the physio-chemical properties of the textile materials. In general, textile-based sampling opens new possibilities for direct chemical analysis of small-volume samples and provide a simple and low-cost method to screen various textiles for their effects on samples to identify which textiles are the most suitable for on-body sensing.     

Determination of dissociation constants of weak acids by deconvolution of proton binding isotherms derived from potentiometric data

Potentiometric titration of six carboxylic acid analytes were measured in aqueous and semiaqueous solvents to determine the effect of the solvent composition on the dissociation constants of the acids. The analytes studied were monoprotic (formic acid, acetic acid), diprotic (maleic and succinic acid) and triprotic (1, 2, ranging in composition from 0 to 80% by volume dioxane. The methodology used to assess the acidity constants was deconvolution of the proton binding isotherm of each analyte in each of the solvents. The dissociation constants agreed with those reported in the literature for titration in water. In the presence of the organic component, correlations relating the acidity constants with properties of the media were also found. In particular, affinity distributions derived from potentiometric titration data were used to assess the solvent media for resolving dissociation constants of weak acids and bases.