Calcium ion selective membrane electrode

The calcium salts of the mono- and diesters of [4-(1,1,3,3-tetramethylbutyl)phenyl phosphoric acid] have been prepared, and the individual esters as well as mixtures of the esters have been used with several varieties of polyvinyl chloride to construct macro membrane electrodes selective to calcium ions. These electrodes have been calibrated by using solutions of CaCl₂ and Ca ion buffers. The mixed ester electrodes showed Nernstian response in the concentration range 10^-1 to 10^-7M; the diester electrodes showed Nernstian response down to 7.9 x 10^-8M. The detection limit of the mixed ester electrode was 10^-8M, whereas that of the diester electrode was 7.9 x 10^-9M. Contrary to these results, the monoester electrodes showed unsatisfactory behavior. The responses of both the mixed ester and diester electrodes to calcium ions were not affected by the presence of sodium, potassium, or other divalent ions. Only ferric and lanthanum ions showed interferences with the electrode response to calcium ions. p]The electrode response was independent of pH in the approximate range 5–8 at a CaCl₂ concentration of 10^-4M. As the Ca ion concentration was increased, the range of pH independence widened to approximately 4–8. The dynamic response time constant of the mixed ester electrode was in the range 0.7–1.5 sec, whereas that of the diester electrode was in the range 0.5–0.75 sec.     

离子选择性电极法测定聚合硫酸铁絮凝剂中的铅

无机高分子絮凝剂聚合硫酸铁(PFS)是我国最有前景的水处理剂之一,其应用领域广泛,除工业废水处理、市政污水处理外还应用于自来水净化处理。目前,制备聚合硫酸铁多采用工业废料,不可避免地含有不同量的铅。国家标准GB14591-1993规定,作为饮用水水处理剂PFS中的铅质量分数不得超过0.0010%。目前用于工业废水中铅量的测定方法有丁基罗丹明B光度法[1]、结晶紫光度法[2]等。光度法测定中必须进行萃取、离子交换、共沉淀等分离富集操作,这就大大增加了分析步骤和操作难度,使铅的吸光光度测定的应用受到一定的限制。最近罗平、郑怀礼等[3,…     

Titrimetric determination of trace sulfur in petroleum using a lead ion selective electrode

Summary A method for the determination of trace total sulfur in petroleum distillates is described. The petroleum sample is combusted using an oxyhydrogen burner. The combustion products are collected in 50 ml of absorber solution containing 10 mg of sodium nitrite and 0.444 mg of sodium sulfate. The excess nitrite is destroyed by boiling. After cooling, sufficient 1,4-dioxane is added to make a 50 volume % solution for the titration. The titration is carried out using –0.5amp polarizing current through a lead ion-selective electrode. Standardized (0.0025M) lead perchlorate is the titrant. The potential break at the endpoint is determined graphically from the titration curve and related to the total sulfur in the petroleum sample.

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Zusammenfassung Ein Verfahren zur Bestimmung von Spuren Gesamtschwefel in Erdöldestillaten wurde beschrieben. Die Probe wird in einer Knallgasflamme verbrannt, die Verbrennungsprodukte werden in 50 ml einer Absorptionslösung aufgefangen, die 10 mg Natriumnitrit und 0,444 mg Natriumsulfat enthält. Das überschüssige Nitrit wird durch Kochen zerstört. Nach dem Abkühlen setzt man der Flüssigkeit das gleiche Volumen Dioxan zu und titriert unter Verwendung einer für Bleiionen spezifischen Elektrode mit einem Polarisationsstrom von –0,5Amp. 0,0025-m Bleiperchlorat dient als Maßlösung. Der Potentialsprung beim Endpunkt wird graphisch ermittelt und entspricht dem Gesamtschwefelgehalt der Probe.

     

Determination of ion adsorption by radioactive tracer technique

Summary The slight linear decrease of the “per mole of AgI adsorbed amount” (ˉC) of the coagulating ion with the increasing pI at a constant concentration of the coagulating ion was proved and explained by the linear decrease of the specific surface. The adsorbed amount of the coagulating ions at a constant concentration and at a given pI decreases with the increasing concentration in which the AgI precipitate was formed. Ions of different valencies are adsorbed in equivalent amounts which are independent of their concentrations which were higher than their coagulation values. The correctness of the desorption-adsorption formula logc″/c′=(z′−z″ a+ logx/(−x) respectivelyS=c″ (1−x)/c′x= 10(z′−z″)a was confirmed (x the fraction of the adsorbed amount of the ion of valencyz″ and concentrationc″, 1−x the fraction of the adsorbed amount of the ion of valencyz′ and concentration c′,S the selectivity coefficient of ion exchangers). Therefore the coagulated AgI can be considered as an ideal ion exchanger. The constanta in the above formula is equal to the slope of the line “log coagulation value-valency” of theSchulze-Hardy rule.

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Zusammenfassung Die leicht lineare Abnahme des pro Mol AgJ adsorbierten Betrages (ˉC) der koagulierenden Ionen mit steigendem p^J bei konstanter Konzentration des koagulierenden Ions wurde gezeigt und durch die lineare Abnahme der spez. Oberfl?che erkl?rt. Der adsorbierte Betrag an koagulierenden Ionen bei konstanter Konzentration und gegebenem p^J sinkt mit steigender Konzentration, mit der die AgJ-F?llung erzeugt wird. Ionen verschiedener Wertigkeiten werden in ?quivalenten Betr?gen unabh?ngig von ihren Konzentrationen adsorbiert und sind h?her als ihre Koagulationswerte. Die Richtigkeit der Desorption-Adsorptions-Formel logc″/c′=(z′−z″ a+logx/(−x) bzw.S=c″ (1−x)/c′x= 10(z′−z″)a wurde sichergestellt (x= Bruchteil des adsorbierten Betrages des Ions der Valenzz″ und dessen Konzentrationc″, 1 −x=Bruchteil des adsorbierten Betrages des Ions der Valenzz′ und der Konzentration c′,S=Selektivit?tskoeffizient des Ionenaustauschers). Deshalb kann das koagulierte AgJ als ein idealer Ionenaustauscher betrachtet werden. Die Konstantea in der obigen Formel ist gleich der Neigung der Kurve “log Koagulationswert/Valenz” in derSchulze-Hardy-Regel (2).

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Contribution number 95 from the Department of Physical Chemistry, Faculty of Sciences, University of Zagreb. Partially reported at the I. Yugoslav Congress for Pure and Applied Chemistry, Zagreb, June 1960.     

Application of an ion selective electrode to study in situ in kinetics of cations exchange in zeolite Y

An ion selective electrode was used successfully to study kinetics of cation exchange as a sensor in situ. Using this method, we have examined forward and reverse ion exchange kinetics in zeolite Y for the MgNa, CaNa, SrNa and BaNa. The effect of different anions, Cu(NO(3))(2), CuSO(4), and Cu(Ac)(2), on the exchange kinetics has also been investigated.     

Thermodynamic study of ion exchange reaction to predict ionic selectivity using ion exchange resin Indion-850

The thermodynamic study was carried out to predict the selectivity behaviour of ion exchange resin Indion-850 towaed various inorganic anions like chloride, iodide, sulfate, and oxalate. The equilibrium constant K _std values for the ion exchange reactions were calculated at different temperatures from which the enthalpy values where obtained. The K _std values were observed to increase with the rise in temperature, indicating endothermic ion exchange reactions. The thermodynamic data obtained here reveal that iodide ions were more strongly retained on the resin surface compared to chloride ions. Also the low enthalpy and high equilibrium constant values for oxalate ions indicate the greater selectivity of ion exchange resin for oxalate ions as compared to sulfate ions.     

Preparation and application of selenite ion selective electrode

A new selenite ion selective electrode using 4,6-dibromopiaselenole as active material, PVC as membrane matrix and dibutyl phthalate as plasticizer has been developed. An analytically useful potential change occurs from about 10(-6)-10(-1)M Se(IV), and the slope of the linear portion is -23.6 mV/10-fold change in Se(IV) concentration at a temperature of 21 degrees . The electrode shows fairly good selectivity for selenite ion over other anions and has been used for the successful determination of total selenium in human hair.     

A selective membrane electrode for iodide ion based on a thiopyrilium ion derivative as a new ionophore

A highly selective electrode for iodide ion based on a thiopyrilium derivative as an excellent ionophore is described. At pH 5.5-8.0, the electrode responds to iodide ion in a linear range from 1.0×10⁻¹ to 8.0×10⁻⁷ M with a slope of 60.2 mV per decade, and a detection limit of 2.0×10⁻⁷ M. Selectivity coefficients determined with the match potential method (MPM) indicate that the interference from inorganic and organic anions is very small. The proposed sensor shows a fast response time of approximately 15 s. It was applied as an indicator electrode in titration of iodide with Ag⁺.     

二氧化铅膜电极用于电解合成苯醌的研究

:本文研究了一种新型的电极———PbO2 膜电极用于以苯酚为原料电解合成苯醌的反应 ,讨论了电解液的酸度、电流密度和苯酚浓度对电流效率的影响。结果表明 ,对于高浓度的苯酚溶液 ,在酸性条件下、保持适中的电流密度能获得较高的电流效率     

茜素S选择电极的研制和应用

本文报道了茜素S电极的研制和应用。比较了季铵盐、季鏻盐、碱性染料和邻二氮菲金属配合盐作为活性物质、各种介体溶剂以及活性物质在膜相中的含量对电极性能的影响。以三辛基甲基氯化铵制成的PVC膜型电极对茜素S在2×10~(-4)～5×10~(-7)M浓度范围内呈Nernstian响应,检测下限为2×10~(-7)M。测定了一些阴离子的选择系数,ClO_4~-,CNS~-,I~-以及能与茜素S配合的金属离子有明显干扰。报道了以茜素S电极为指示电极,用EDTA和茜素S为滴定剂滴定钪和稀土的情况。以茜素8电位滴定钪及钴-钐合金中的钐,都获得良好的结果。     

Effect of electrode membrane surface ratio and thickness on lead electrode potential

Summary The lead ion selective electrode (ISE) consisting of PbS-Ag₂S is normally used with a membrane surface of outer layer areaA _o) and inner layer area (A _i) at unity (A _o=A _i). Partial covering of one surface area with an insulating material and keeping the other surface layer intact resulted in different ratios of membrane surface areas exposed to lead solutions. The potential linearly increased with increasing theA _o/A _i ratio and decreased with decreasing theA _o/A _i ratio. The lead ISE potential increased linearly with increasing the membrane thickness, but which required much longer time for a stable potential.

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Wirkung von Oberflächenverhältnis und Dicke der Elektrodenmembran auf das Potential einer Bleielektrode

Zusammenfassung Die aus PbS-Ag₂S bestehende spezifische Bleiionen-Elektrode wird üblicherweise mit einem Oberflächenverhältnis der Außenfläche (A _o) und der Innenfläche (A _i) mitA _o=A _i verwendet. Durch teilweise Abdeckung einer Oberfläche mit isolierendem Material, ohne daß die andere Oberfläche verändert wird, ergaben sich verschiedene Verhältnisse der mit der Bleilösung in Berührung stehenden Oberflächen. Mit dem VerhältnisA _o/A _i stieg das Potential linear an bzw. es fiel mit diesem Verhältnis ab. Das Potential der spezifischen Bleielektrode stieg mit der Dicke der Membran, stabilisierte sich aber wesentlich langsamer.

     

Lead ion selective PVC membrane electrode based on 5,5'-dithiobis-(2-nitrobenzoic acid)

A PVC membrane electrode for lead ions based on 5,5′-dithiobis-(2-nitrobenzoic acid) as membrane carrier was prepared. The electrode exhibits a Nernstian response for Pb²⁺ over a wide concentration range (1.0×10⁻²–4.0×10⁻⁶ M). It has a relatively fast response time and can be used for at least 3 months without any divergence in potentials. The proposed electrode revealed good selectivities for Pb²⁺ over a wide variety of other metal ions and could be used in a pH range of 2.0–7.0. It was used as an indicator electrode in potentiometric titration of lead ions and in direct determination of lead in water samples.     

Copper (II) ion selective liquid membrane electrode based on new Schiff base carrier

Cu2+ selective PVC membrane electrode based on new Schiff base 2, 2'-[1,9 nonanediyl bis (nitriloethylidyne)]-bis-(1-naphthol) as a selective carrier was constructed. The electrode exhibited a linear potential response within the activity range of 1.0 x 10(-6) - 5.0 x 10(-3) moll(-1) with a Nernstian slope of 29 +/- 1 mV decade(-1) of Cu2+ activity and a limit of detection 8.0 x 10(-7) mol l(-1). The response time of the electrode was fast, 10 s, and stable potentials were obtained within the pH range of 3.5- 6.5. The potentiometric selectivity coefficients were evaluated using two solution method and revealed no important interferences except for Ag+ ion. The proposed electrode was applied as an indicator electrode to potentiometric titration of Cu2+ ions and determination of Cu2+ content in real samples such as black tea leaves and multivitamin capsule.     

Iodide-induced adsorption of lead(II) ion on a glassy carbon electrode modified with ferroferric oxide nanoparticles

Spherical Fe₃O₄ nanoparticles (NPs) were prepared by hydrothermal synthesis and characterized by scanning electron microscopy and X-ray diffraction. A glassy carbon electrode was modified with such NPs to result in a sensor for Pb(II) that is based on the strong inducing adsorption ability of iodide. The electrode gives a pair of well-defined redox peaks for Pb(II) in pH 5.0 buffer containing 10 mM concentrations of potassium iodide, with anodic and cathodic peak potentials at ?487 mV and ?622 mV (vs. Ag/AgCl), respectively. The amperometric response to Pb(II) is linear in the range from 0.10 to 44 nM, and the detection limit is 40 pM at an SNR of 3. The sensor exhibits high selectivity and reproducibility.

Conducting polymer ion sensor electrodes-III. Potentiometric sulfide ion selective electrode

A new potentiometric sensor electrode for sulfide based on conducting polymer films is introduced. The electrode is formed by electrochemically depositing a film of poly(3-methylthiophene) and poly(dibenzo-18-crown-6) onto an alloy substrate. Different methods were used for the electrode preparations. The alloy used has a low melting point, which allowed its use for manufacturing a microsize version of this electrode. The electrode response is stable for 3 days. The working temperature range for this electrode is between 10 and 40 degrees C. The linear dynamic range is 1.0x10(-7)-1.0x10(-2) M and measures total sulfide concentration over a range of pH from 1 to 13. The polymer electrode showed high selectivity for sulfide in the presence of many common interfering anions. The electrode is useful for the measurement of total sulfide in biological environments and can be manufactured in the micron scale. Therefore, it will be useful for the measurement within biofilms.