银量法电位滴定测定盐酸苯海拉明霜

盐酸苯海拉明为常用的抗过敏药,外用治疗急性及亚急性湿疹、过敏性皮炎等。目前,盐酸苯海拉明霜已成为皮肤科常用制剂之一。但尚无检验标准。笔者对其含量测定方法进行中和法和非水滴定法测定,由于中和法受酸值影响,而非水滴定法较繁琐费时,故用电位滴定法测其含量,结果较为满意,现介绍如下;

络合物的电位滴定法测定

印度研究人员用氟离子选择电极以电位滴定法测定了1mol/L（HClO4、NaClO4）介质中铈（Ⅳ）的氟化络合物的稳定性常数。实验人员用AgO氧化,接着快速加入已知量氟离子,这样可使铈定量氧化成四价并稳定存在于过氯酸介质中。这种方法保证了氧化态的稳定性并防止了Ce（Ⅳ）的水解和聚合。

用电位滴定法测定镧系元素离子与某些席夫碱和苯并噻唑啉络合物稳定性常数

土耳其研究人员P.G(?)rkan等在25±0.1℃下的乙醇-水溶液(1∶1V/V)中,用电位滴定法测定了5种席夫碱和2种苯并噻唑啉型配位体的质子化常数及其与6种镧系离子的络合物的稳定性常数。席夫碱型配位体是亚水杨基—2—亚胺吡啶(SAPy),亚水杨基—5—甲基—2—亚胺吡啶(SAPyMe),亚水杨基—5—氯—2—亚胺吡啶(SAPyCl)。

烷基磷酸酯中单、双酯含量的测定

根据磷酸三步离解原理 ,采用电位滴定的方法 ,快速测定烷基磷酸酯中单、双酯含量。为准确控制磷酸酯合成工艺及产品质量 ,提供了一种简便有效的方法。

乳糖酸红霉素中游离的乳糖酸检验方法的探讨

目的:测定乳糖酸红霉素中游离的乳糖酸的量。方法:采用电位滴定法。结论:该方法不适合检测目前国内生产的乳糖酸红霉素中游离的乳糖酸的量。

市售酱油中总酸及氨基酸态氮的测定

利用电位滴定法,对六安市售13种酱油进行分析,测定出市售酱油中的总酸及氨基酸态氮的合格率分别为100%和7.69%.

Determination of Formation Constants of Co￣(2+), Ni￣(2+),Cu￣(2+) and Zn￣(2+) Complexes with Humic and Fulvic Acidsby Potentiometric Titration Method

The formation constants of Co￣(2+), Ni￣(2+), Cu￣(2+) and Zn￣(2+) complexes with humic acid (HA) and fulvicacid (FA) in red soil were determined by the potentiometric titration method. The constants as a functionof composition of the complexation solutions were obtained by two graphical approaches respectively Theformation constants decreased with increasing concentration of metal in the solution. The results provideunambiguous evidence for the heterogeneity of the function groups of humic substances. The formationconstants of FA were much smaller than those of HA, and the formation constants of Cu￣(2+) were muchgreater than those of Co￣(2+) , Ni￣(2+) and Zn￣(2+) . The potentiometric titration method for determining formationconstants are also discussed in the article.

Acid Dissociation Constants of Functional Groups in Humic Substances:I.Affinity Spectrum Model Analysis of Potentiometric Data of Fulvic and Humic Acids Solutions from Weathered Coal and Dark Loessial Soil

Potentiometric experiments were carried out on the proton binding equilibria of FA extracted from a weathered coal and HA and Fa extracted from a dark loessial soil.The affinity spectrum model was employed to treat the experimental data.The affinity spectrum model technique could“magnify” the heterogeneity of the proton binding equilibria.so it was useful for comparing and studying the characteristics of humic substances with similar properties.According to the affinity spectra,we also found that the direction of the titration could affect the properties of the equilibria of FA from the weathered coal,and the acidic functional groups contained in FA from the weathered coal were larger in quantity than those contained in HA and FA from the dark loessial soil.

The sorption mechanisms of Th(Ⅳ) on attapulgite

The surface properties of intrinsic and activated attapulgite were studied using potentiometric titration. The sorption mechanisms of Th（IV） on intrinsic and activated attapulgite were investigated by employing surface complexation model and FITEQL 3.2 code. The results indicated that the sorption sites of intrinsic attapulgite involved in the sorption process were main ion exchange site （ ≡ XNa/K）, strong site （≡ SsOH） and weak site （ ≡ SwOH）, while only strong site （ ≡SSOH） and weak site （≡SwOH） were predominant for activated attapulgite. At pH 〈 2.5, the species of Th（IV） was main Th4＋ in aqueous solution; then the hydrolysis species of Th（IV） （i.e., Th（OH）22＋, Th（OH）3＋ and Yh（OH）40） gradually formed as pH increasing. For the sorption of Th（IV） on intrinsic attapulgite, both ion exchange species （ ≡ X2Th） and inner-sphere surface complexes （ ≡ SsOTh） were dominant, while only inner-sphere surface complexes （i.e., ≡SSOThOH and ≡ SWOTh） were observed for Th（IV） sorption to activated attapulgite. In the presence of humic acid （HA）, the sorption of Th（IV） on activated attapulgite was obviously enhanced; and both ≡ SsOH-HA-Th and≡ SSOTh were the predominant speciation. It was also interesting to find that the addition of HA obviously provoked the desorption behavior of Th（IV）.

Sodium ion storage performance and mechanism in orthorhombic V_(2)O_(5) single-crystalline nanowires

A fundamental understanding of the electrochemical reaction process and mechanism of electrodes is very crucial for developing high-performance electrode materials.In this study,we report the sodium ion storage behavior and mechanism of orthorhombic V_(2)O_(5) single-crystalline nanowires in the voltage window of 1.0–4.0 V(vs.Na/Na+).The single-crystalline nanowires exhibit a large irreversible capacity loss during the first discharge/charge cycle,and then show excellent cycling stability in the following cycles.At a current density of 100 mA g^(−1),the nanowires electrode delivers initial discharge/charge capacity of 217/88 mA h g^(−1),corresponding to a Coulombic efficiency of only 40.5%;after 100 cycles,the electrode remains a reversible discharge capacity of 78 mA h g^(−1) with a fading rate of only 0.09%per cycle compared with the 2nd cycle discharge capacity.The sodium ion storage mechanism was investigated,illustrating that the large irreversible capacity loss in the first cycle can be attributed to the initially formed single-crystalline α′-Nax V_(2)O_(5)(0.02<x<0.88),in which sodium ions cannot be electrochemically extracted and the α′-Na0.88 V_(2)O_(5) can reversibly host and release sodium ions via a single-phase(solid solution)reaction,leading to excellent cycling stability.The Na^(+) diffusion coefficient in α′-Nax V_(2)O_(5) ranges from 10^(−12) to 10^(−11.5) cm^(2) s^(−1) as evaluated by galvanostatic intermittent titration technique(GITT).