Semi-automatic catalytic titration of ethylenediaminetetraacetic acid and metal ions with the 1,4-dihydroxyphthalimide dithiosemicarbazone— aerial oxygen system as indicator reaction

A semi-automatic spectrophotometric method is described for the catalytic titration of ethylenediaminetetraacetic acid, based on its inhibitory effect on the manganese (II)catalyzed aerial oxidation of 1,4-dihydroxyphthalimide dithiosemicarbazone. Amounts of EDTA in the 750–4000-μg range can be determined with a relative standard deviation of ca 0. 6% (n = 11). Methods are also described for the indirect catalytic titrations of manganese(II) and nickel(II)in the ranges 20–450 μg and 40–1000 μg, respectively, with relative standard deviations (n = 11) of ca. 1%.     

Liquid-membrane type diethyldithiocarbamate ion-selective electrode and its application to the potentiometric titration of metal ions

Summary A liquid-membrane type diethyldithiocarbamate ion-selective electrode (DDC-ISE) was constructed by utilizing the nitrobenzene extract of the methyltrioctylammonium-DDC ion-pair. The DDC-ISE shows Nernstian response in the concentration range of 10^–5–10^–1 M DDC in 0.1 M sodium hydroxide solution. The electrode potential is constant in the pH range of 7.6–13.0. Potentiometric titrations of Hg(II), Cu(II), Ni(II) and Zn(II) in ammoniacal solutions with NaDDC and successive titration of two binary systems, Hg(II)-Ni(II) and Hg(II)-Zn(II), were successfully carried out with this electrode.

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Diethyldithiocarbamat-ionenselektive Flüssig-Membranelektrode und ihre Anwendung zur potentiometrischen Titration von Metallionen

Zusammenfassung Eine Diethyldithiocarbamat-ionenselektive Flüssig-Membranelektrode (DDC-ISE) wurde entwickelt, die den Nitrobenzolextrakt des Ionenpaares Methyltrioctylammonium-DDC benutzt. Die DDC-ISE zeigt Nernstsches Ansprech-Verhalten im Konzentrationsbereich von 10^–5–10^–1 M DDC in 0,1 M Natriumhydroxidlösung. Das Elektrodenpotential ist im pH-Bereich von 7,6–13,0 konstant. Potentiometrische Titrationen von Hg(II), Cu(II), Ni(II) und Zn(II) mit NaDDC in ammoniakalischer Lösung sowie sukzessive Titrationen der binären Systeme Hg(II)-Ni(II) und Hg(II) — Zn(II) wurden erfolgreich durchgeführt.

     

Liquid-membrane type 8-quinolinol-5-sulfonate ion selective electrode and its application to potentiometric titration

A nitrobenzene extract of the ion-pair consisting of 8-quinolinol-5-sulfonate (Hqs^?) and the cation of zephiramine (Z⁺Cl^?, benzyldimethyltetradecylammonium chloride) was used as an ion-exchanging liquid membrane for the electrode responding to Hqs^? ion. The potential response showed the Nernstian slope with the Hqs^? activities varying from 10^?2 to 10^?4.5 mol l^?1. The break points in the potential-pH plot with the constant analytical concentration of H₂qs correspond to the values of the negative logarithm of the acid dissociation constant of H₂qs. The present electrode was successfully applied to the potentiometric titration of copper(II) with H₂qs.     

Semi-automatic catalytic titration of some aminopoly-carboxylic acids,copper(II), and cobalt(II)

Summary A semi-automatic potentiometric method is described for the catalytic titrimetric determination ofg amounts of some aminopolycarboxylic acids. The method is based on their inhibitory effect on the copper(II)-catalyzed periodate-thiosulfate reaction. Amounts of EDTA in the 0.7–600g range (10^–6–8×10^–5 M), of DCTA in the 7–7000g range (10^–6–10^–3 M), of EGTA in the 0.8–800g range (10^–7–10^–4 M), and of DTPA in the 4–800g range (5×10^–7–10^–4 M) were determined with average relative errors and coefficient of variation of about 0.4–1%. The method has also been used for the indirect catalytic titrimetric determination ofg amounts of Cu²⁺ and Co²⁺ ions with about the before mentioned accuracy and precision.

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Halbautomatische katalytische Titration einiger Aminopolycarbonsäuren sowie von Cu(II) und Co(II)

Zusammenfassung Eine halbautomatische potentiometrische Methode zur katalytischen Maßanalyse von Mikrogrammengen einiger Aminopolycarbonsäuren wurde angegeben. Sie beruht auf dem Hinderungseffekt gegenüber der Cu(II)katalysierten Perjodat-Thiosulfatreaktion. EDTA in Mengen von 0,7–600g, DCTA in Mengen von 7–7000g, EGTA in Mengen von 0,8–800g und DTPA in Mengen von 4–800g wurden mit einem mittleren relativen Fehler von etwa 0,4–1% bestimmt. Das Verfahren wurde auch zur Bestimmung von Cu(II) und Co(II) mit der angeführten Genauigkeit verwendet.

     

A survey on cobalt metallurgical processes and its application

The Cobalt (Co) transition element in the recent years have been a new research area with increased trends in inorganic chemistry. The Co is used in several areas for example ceramics, technologies, additive manufacturing, rechargeable batteries in manufacturing firms. The magnets, and alloys, digital processing, bio-essentiality, Healthcare computing, sustainable development, storage of renewable energy, biogas amongst others are entailed. In this study, the Co Metallurgical processes are presented and how they are used. This is because of its low resistance in smaller geometries and capacity to work through a thinner barrier. This paper avails the purification process of Co from its ores. Presented a diagrammatic illustration of Co within an adverse aspect. This in return avails all fundamental research content that can facilitate the researchers in opposing models and frame works that are state-of-art in elements purification processes.     

Development of highly sensitive cadmium iondashselective electrodes by titration method and its application to cadmium ion determination in industrial waste water

Characteristics of cadmium iondashselective electrode made cadmium sulphide (CdS)-silver sulphide (Ag(2)S) mixture were studied. CdS-Ag(2)S mixtures were obtained by gas/solid-phase reaction between silver-cadmium mixed powder and hydrogen sulphide gas (dry method) and by ionic reaction between cadmium-silver mixed ions and sulphide ion (wet method). As a result, it was found that the CdS-Ag(2)S mixture had to be made in the condition of excess existence of sulfur and had better regulate the excess sulfur quantity minimum, for the CdS-Ag(2)S pressed membrane gave a good Nernstian response against the cadmium ion concentration change. As the best way, CdS-Ag(2)S mixture was obtained by adding sulphide ion solution to 5 mol% cadmium ion and 95 mol% silver ion mixed solution while measuring silver sulphide (Ag(2)S) electrode potential as an indicator electrode. According to the reaction was stopped when the potential variation from the initial potential in the sulphide ion solution reached at 87-116 mV which the sulphide ion concentration became 10(-3) - 10(-4) of the initial concentration, the cadmium ion membrane pressed diameter of 8 mm and thickness of 2 mm showed a Nernstian response from 10(-8) to 10(-1) M of cadmium ion concentration. Furthermore, aiming to its application for industrial waste water, masking buffer for interfering metal ions such as lead ion (Pb(2+)) and copper ion (Cu(2+)), which were possibly coexisted and to adjust total ionic strength and pH of sample was developed. The present Cd(2+) iondashselective electrode was applied to the determination of Cd(2+) in the industrial waste water. The good regression line with correlation factor of 0.984 was obtained compared with the conventional atomic absorption spectroscopy.     

催化滴定 III: 影响EDTA滴定金属离子时突跃的因素

本文探讨以催化反应指示终点直接用EDTA滴定金属离子时影响突跃的因素. 采用滴定曲线突跃部分的斜率, tanθ, 作为指示反应速率的表征. 通过实验探讨了PH、CuEDTA和NiTrien用量以及滴定速率对tanθ的影响, 并从理论上导出tanθ的近似表达式, 它是NiTrien的起始浓度、加入EDTA的速率以及EDTA与NiTrien的反应速率常数三个变量的线性函数, 利用这一表达式可对实验结果作出较为满意的解释.     

Automatic catalytic titration of silver

An automatic method is described for the catalytic titrimetric determination of microgram amounts of silver. The method is simple and accurate, and is based on the inhibitory effect of silver ions on the iodide-catalysed Ce(IV)-As(III) reaction. The end-point of titration with iodide is determined either automatically by the second- derivative technique or from the recorded potentiometric or spectrophotometric curves. Microamounts of silver in the range 1–2000 μg were determined with relative errors of about 0.7%.     

离子印迹材料的发展及在识别吸附重金属中的应用

金属离子的识别和选择性研究仍是当前水体金属离子污染分析中一大挑战。离子印迹材料具有制备简单、结构稳定、识别性强、吸附速率快、吸附容量大和易回收等特点,在离子分离、富集和传感识别等领域受到广泛的关注。在过去的研究中,有两方面重点内容始终贯穿离子印迹材料的发展历程。一是印迹材料的制备过程的优化,二是识别性能以及识别机理的研究。本文按照时间轴的顺序对离子印迹材料的发展进行综述,并重点归纳了制备过程和识别机理的研究进展。另外对现阶段离子印迹材料在识别吸附重金属中的应用进行了总结和展望。     

Improving metal ion specificity during in vitro selection of catalytic DNA

Metal ions play important roles in both the structure and function of catalytic DNA and RNA. While most natural catalytic RNA molecules (ribozymes) are active in solutions containing Mg(2+), in vitro selection makes it possible to search for new catalytic DNA/RNA that are specific for other metal ions. However, previous studies have indicated that the in vitro selection protocols often resulted in catalytic DNA/RNA that were equally active or sometimes even more active with metal ions other than the metal ion of choice. To improve the metal ion specificity during the in vitro selection process, we implemented a negative selection strategy where the nucleic acid pool was subjected to a solution containing competing metal ions. As a result, those nucleic acids that were active with those metal ions are discarded. To demonstrate the effectiveness of the negative selection strategy, we carried out two parallel in vitro selections of Co(2+)-dependent catalytic DNA. When no negative selection was used in the selection process, the resulting catalytic DNA molecules were more active in solutions of Zn(2+) and Pb(2+) than in Co(2+). On the other hand, when the negative selection steps were inserted between the normal positive selection steps, the resulting catalytic DNA molecules were much more active with Co(2+) than in other metal ions including Zn(2+) and Pb(2+). These results suggest strongly that in vitro selection can be used to obtain highly active and specific transition metal ion-dependent catalytic DNA/RNA, which hold great promise as versatile and efficient endonucleases as well as sensitive and selective metal ion sensors.     

Electrothermal atomic-absorption spectrometry of arsenic and its application to environmental samples

Electrothermal atomization of arsenic with a metal micro-tube atomizer has been studied. Thiourea and thionalide were found to give effective atomization of arsenic. A method involving extraction of the thionalide complex for determining traces of arsenic in water and soil is described.     

Moving window as a variable selection method in potentiometric titration multivariate calibration and its application to the simultaneous determination of ions in Raschig synthesis mixtures

A novel method based on moving window (MW) strategy has been proposed to simultaneously choose the optimal pH region and latent variables (LVs) number for partial least squares (PLS) regression in potentiometric titration multivariate calibration. In this method, the leave‐one‐out cross‐validation with varying LVs number is run on different selected MW and, consequently, that revealing optimal results is selected. The method is applied to the simultaneous determination of H⁺, NH₃OH⁺ and NH in Raschig synthesis mixtures, which is of industrial importance. A comparison in the modeling power of PLS is made between non‐processed data set and data set processed by the MW method. Copyright © 2008 John Wiley & Sons, Ltd.     

乙酰丙酮基聚苯乙烯在萃取金属离子上的应用

大孔的苯乙烯-二乙烯苯共聚物经氯甲基化后,分别与乙酰丙酮镍、乙酰丙酮钠和四正丁基乙酰丙酮铵三种不同的乙酰丙酮盐反应,可制得聚3-(p-乙烯苄基)戊二酮-[2,4]。其中以由乙酰丙酮镍制得的聚合物最好,除二乙烯苯外,78%左右的苯环乙酰丙酮化了。该聚合物螯合Fe~(3 )和Ni~(2 )的能力与β-二酮基高聚物相仿或稍优。还比较了此类高聚物的物理机械性能。     

Simultaneous determination of metal ion concentrations in binary mixtures with a multi-LED photometer

 A compact photometer is based on up to seven different light-emitting diodes whose light is guided into a photometric cell by means of a fibre-optic coupler. The wavelength is selected by switching on the appropriate light source. The application of this multi-wavelength photometer to the determination of binary metal ion samples is demonstrated using model mixtures. Solutions of Fe, Co, Cu, Ni, Cr and Mn were used in combination with several photometric reagents. It was found that the instrument yielded concentration measurements which were usually within a few percent of the correct concentration. These results are comparable to reported data obtained with conventional instruments for similar measurements. The application of the instrument for simultaneous determination in flow-injection analysis employing rapid computer controlled switching of the light-emitting diodes is also demonstrated. A limitation in the use of light-emitting diodes for the simultaneous determination was found to arise from the fact that in some instances non-linear calibration curves are obtained when employing light-emitting diodes as light sources. This occurs when the absorptivity of the measured compound changes over the emission band of the diodes. Multiple regression analysis is then not easily possible. Received: 16 September 1996/Revised: 14 October 1996/Accepted: 16 October 1996     

Simultaneous kinetic determination of metal ion mixtures based on a ligand substitution reaction

The rates of the ligand substitution reactions between 2-(4-sulfophenylazo)-l,8-dihydroxy-3, 6-naphthalenedisulfonic acid (SPADNS) complexes of Co²⁺, Ni²⁺, Pb²⁺ and Cu²⁺ and EDTA (or CDTA) have been studied at 25.0°C, pH 8.0–9.3, by stopped-flow spectrophotometry. The reactions are first order in SPADNS complex and in incoming ligand. The absorbance change during the reaction progress can be kinetically separated for each component of a mixture, so that metal ions down to 10^-6 M can be determined. Components of very high reactivity, such as Cd²⁺, Mn²⁺ or Zn²⁺, can also be determined as part of a multicomponent mixture.     

Coulometric titration of thallous ion with electrogenerated ferricyanide ion

Thallous ion can be coulometrically titrated to thallic oxide in strongly alkaline medium by means of ferricyanide ion generated by anodic oxidation of ferrocyanide ion at a platinum anode. The equivalence point may be detected either potentiometrically or amperometrically. With 8 to 20 mg of thallous ion in 125 ml the accuracy and precision are within ± 0.2%.     

Spectrophotometric determination of titanium with N-m-Tolyl-N-phenylhydroxylamine and its application to environmental samples

N-m-Tolyl-n-phenylhydroxylamine is proposed for the spectrophotometric determination of titanium. The reagent forms a yellow chloroform-soluble complex with titanium in media with a hydrochloric acid concentration of at least 9M. The apparent molar absorptivity at 380 nm is 7.4 x 10(3) 1.mole(-1).cm(-1). The optimum final concentration range is 0-54 mug of titanium in 10 ml of chloroform. The complex contains the metal and reagent in 1:2 ratio. The proposed method has been successfully applied to the determination of titanium in coal, coal fly-ash, pond sediment and asphalt.