Determination of Fluoride Ions in Mouthwash Samples by a PVC Membrane Samarium(III) Sensor

Abstract

In this study, a new ion-selective electrode for Sm³⁺ is described, illustrating 2-[(E)-1-(1H-pyrrol-2-yl)methylidene]-1-hydrazinecarbothioamide (PMH) in a poly(vinylchloride) (PVC) membrane with nitrobenzene (NB) as a plasticizer and sodium tetraphenyl borate (NaTPB) as an anionic additive. The proposed sensor exhibited a Nernstian response for Sm³⁺ ions over a wide concentration range between 1.0 × 10^?2 and 1 × 10^?6 M, with a detection limit of 5.2 × 10^?7 M in the pH range of 4.2–8.5. Moreover, the sensor displayed the Nernstian slope of 19.8 ± 0.3 mV per decade, having a fast response time within 10 s over the entire concentration range. This electrode presented very good selectivity and sensitivity toward the Sm³⁺ ions over a wide variety of cations, including alkali, alkaline earth, transition-metal, and heavy-metal ions. It was used as an indicator electrode in the potentiometric titration of Sm³⁺ ions with EDTA. The membrane sensor was also applied to the determination of fluoride ions in mouthwash samples.     

Original Potentiometric Ytterbium(III) PVC-Membrane Sensor Based on N1,N2-Bis-[1-(2-hydroxy-1,2-diphenyl)ethylidene]ethanedihydrazide

Abstract

In this work, we describe the construction, performance, and applications of an original ytterbium(III) sensor based on N¹,N²-bis-[1-(2-hydroxy-1,2-diphenyl)ethylidene]ethanedihydrazide (BHDEH), which acts as a suitable carrier. Because it has a low detection limit of 4.2 × 10^?7 M, the sensor response for the Yb(III) ion is Nernstian over a wide concentration range: four decades of concentration (1.0 × 10^?6 to 1.0 × 10^?2 M). The response time of the electrode is less than 10 s, it can be used in the pH range of 3.2–8.3, and its duration is at least 2 months without any considerable potential divergence. The sensor revealed very good selectivity for Yb(III) in the presence of several metal ions. To investigate the sensor analytical applicability, it was tested as an indicator electrode in the potentiometric titration of Yb(III) solution with standard EDTA solution. The proposed electrode was also used to determine fluoride ions in mouthwash.     

Samarium(III)-PVC-Membrane Sensor Based on Ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline

Abstract

2-Ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (EED) was found to be a suitable neutral ionophore for the preparation of a highly selective samarium (Sm)(III) membrane sensor. Poly vinylchloride (PVC)–based membranes of EED with sodium tetraphenyl borate (NaTPB) as an anionic additive and dibutylphthalate (DBP), nitrobenzene (NB), and acetophenone (AP) as plasticizing solvent mediators were prepared and investigated as Sm(III) sensors. The sensor exhibited a Nernstian response over a concentration range of 1.0 × 10^?6 to 1.0 × 10^?2 M, with a detection limit of 5.0 × 10^?7 M. The best performance was achieved with a membrane composition of 30% PVC, 66% dibutyl phthalate (DBP), 2% EED, and 2% sodium tetraphenyl borate (NaTPB). It has a very short response time, in the whole concentration range (～10s), and can be used for at least 10 weeks. The proposed electrode shows a very good selectivity toward Sm(III) ions over a wide variety of cations, including alkali, alkaline earth, transition-metal, and heavy-metal ions. The sensor was applied to the determination of Sm ions in binary mixtures.     

Determination of Ytterbium(III) Ions in Soil and Sediment Samples by a New Polymeric Yb3+-PVC Membrane Sensor

Abstract

A polyvinyl chloride (PVC) membrane sensor for ytterbium(III) ions was prepared, based on 2,5-bis(5-tert-butyl-benzoxazol-2-yl)thiophene (BBT) as a membrane carrier. The sensor illustrates the following characteristics: a linear dynamic range of 1.0 × 10^?6 to 1.0 × 10^?2 M; a Nernstian slope of 19.7 ± 0.5 mV decade^?1; a detection limit of 4.4 × 10^?7 M; a response time of <10 s; and use for at least 2 months without any significant potential divergence in the pH range of 3.5–8.4. Moreover, the recommended selective sensor revealed a comparatively satisfactory selectivity regarding most of the alkali and alkaline earth ions and some of the transition-metal and heavy-metal ions. In fact, it was used as an indicator electrode in the Yb(III) potentiometric titration with ethylene diamine tetra-acetic acid (EDTA) and the determination of concentration of Yb(III) ions in soil and sediment samples.     

Terbium(III) Ion-Selective Electrochemical Sensor Based on Hematoporphyrin

Abstract

A polyvinyl chloride (PVC) based membrane sensor for terbium ions was prepared by employing Hematoporphyrin (HP) as an ionophore. The sensor revealed a very good selectivity (expect for the Fe³⁺ion) with respect to common alkali, alkaline earth and heavy metal ions. The plasticized membrane electrode exhibits a Nernstian response for Tb³⁺ ions over a wide concentration range (1.0 × 10^?6 ? 1.0 × 10^?2 M) with a slope of 19.8±0.3 mV per decade and low detection limit of 7.4 × 10^?7 M. The developed sensor was used in determination of F^? in mouth wash preparation sample.     

Tb3+ PVC-Membrane Electrode Based on 2-{2-(2-Anilinocarbothioyl)hydrazino)-2-oxoacetyl}-N-phenyl-1-hydrazine Carbothioamide

Abstract

The polyvinyl chloride (PVC) membrane containing 2-{2-(2-anilinocarbothioyl)hydrazino)-2-oxoacetyl}-N-phenyl-1-hydrazinecarbothioamide (AHC) as a suitable iophore exhibits a Nernstian response for Tb³⁺ ions over a wide concentration range (1.0 × 10^?6 to 1.0 × 10^?2 M) with a slope of 19.6 ± 0.3 mV per decade and a limit of detection of 6.8 × 10^?7 M in the pH range 3.5–8.5. The proposed sensor revealed very good selectivities (expect for the Pr³⁺ and Ho³⁺ ions) for a wide variety of other metal ions. The practical utility of the electrodes has been demonstrated by its use for the determination of Tb³⁺ in different solutions.     

Magnesium-PVC Membrane Sensor Based on 4,5-Bis(Benzoylthio)-1,3-Dithiole-2-Thione

Abstract

This report describes an attempt to develop potentiometric Mg²⁺ sensors based on a liquid polymeric membrane. Membrane incorporating 4,5-Bis(benzoylthio)-1,3- dithiole-2-thione (Bz₂dmit) as ionophore, with composition Bz₂ dmit:NaTPB:NB:PVC in the ratio 2.5:2.5:65:30 (w/w), exhibits the best result for potentiometric sensing of Mg²⁺ ions. The proposed electrode, based on Bz₂ dmitwith nitrobenzene (NB) as a solvent mediator in a polyvinyl chloride (PVC) membrane matrix, exhibited a near-Nernstian response to Mg²⁺ in the concentration range of 1.0 × 10^?5 to 1.0 × 10^?1 M, with a slope of 29.2 mV per decade of activity of Mg²⁺. The lower limit of detection was 1.0 × 10^?5 M. This sensor showed high selectivity with respect to alkaline, alkaline earth, transition, and heavy metal ions, except for Sr²⁺, and could be used over a pH range of 3.5–9.0. It can be used for at least 2 mo without considerable divergence in potentials and has a relatively fast response of <10 s. It was applied successfully as an indicator electrode in potentiometric titration of Mg²⁺ ions with EDTA.     

4—（2—噻唑偶氮）—2,4—二氨基甲苯与铑显色反应的研究

本研究了４－（２－噻唑偶氮）－２，４－二氨基甲苯（简称ＴＡＤＡＴ）与铑的显色反应。在ｐＨ＝３．７～４．９的酸度范围内试剂与铑形成红色络合物，加入无机酸后色泽加深，络合物的最大吸收位于５９０ｎｍ，表观摩尔吸光系数为１．１×１０＾５Ｌ·ｍｏｌ＾－１·ｃｍ＾－１，其组成为Ｒｈ：ＴＡＤＡＴ＝１：３。铑浓度在０～１２μｇ／２５ｍｌ范围内服从比尔定律。该方法用于模拟样中铑的测定，结果满意。     

Determination of Trace Amounts of Cobalt in Natural Water Samples as 4-(2-Thiazolylazo) Recorcinol Complex After Adsorptive Preconcentration

ABSTRACT

A chromatographic method has been established for the determination of trace amounts of cobalt by preconcentration on Amberlite XAD-16 resin as cobalt/4-(2-Thiazolylazo) resorcinol (TAR) complexes. The conditions (e.g. pH, resin amounts, matrix ions) affecting the recovery of cobalt from aqueous solution were studied. The method has been employed for the determination of cobalt in natural water samples.     

Determination of Dysprosium(III) Ion in Soil and Sediment Samples by an Original Potentiometric Dysprosium(III) Membrane Sensor

Abstract

A PVC membrane electrode for dysprosium(III) [Dy(III)] ions was constructed, having its basis on benzoxazoleguanidine (BG) as a suitable ionophore. The sensor presents a linear dynamic range of 1.0 × 10^?6–1.0 × 10^?1 M, with a Nernstian slope of 19.5 ± 0.4 mV decade^?1 and a detection limit of 4.7 × 10^?7 M. The response time is quick (less than 10 s). It can be used in the pH range of 3.3–8.4, and its duration is at least 2 mo without any considerable, noticeable potential divergence. The recommended sensor revealed comparatively good selectivity with respect to most alkali, alkaline earth, some transition, and heavy metal ions. It was successfully employed as an indicator electrode in the potentiometric titration of Dy(III) ions with EDTA. The membrane sensor also applied to the determination of concentration of Dy(III) ions in soil and sediment samples. Validation with certified reference materials (CRMs) was also carried out.     

A new ytterbium(III) PVC membrane electrode based on 6-methy-4-{[1-(1H-pyrrol-2-yl)methylidene]amino}-3-thioxo-3,4dihydro-1,2,4-triazin-5(2H)-one

This study presents the development of an original electrode, employing 6-methy-4-{[1-(1H-pyrrol-2-yl)methylidene]amino}-3-thioxo-3,4dihydro-1,2,4-triazin-5(2H)-one (PMTO) as a suitable ionophore. Interestingly, the electrode performance provided a very good response for Yb³⁺ in a wide concentration range (from 1.0 × 10⁻⁶ to 1.0 × 10⁻¹ mol L⁻¹) with a detection limit of 4.6 × 10⁻⁷ mol L⁻¹ and a slope of 19.5 ± 0.3 mV per decade of Yb³⁺ concentration. Furthermore, it possessed a fast response time of about 10 s and it functioned in the pH range of 3.3-8.0 with a usage of at least 2 months without observing any deviations. Noticeably, the proposed electrode revealed an excellent selectivity for Yb³⁺ over a broad variety of alkali, alkaline earth, transition and heavy metal ions. The practical applicability of the electrode was demonstrated by its utilization as an indicator electrode in the potentiometric titration of Yb³⁺ ions with EDTA and in the determination of F⁻ in mouth wash samples. Additionally, it was also applied for the determination of Yb³⁺ ions in binary mixtures.     

锰与4-(2-噻唑偶氮)间苯二酚络合吸附波的研究及应用

本文研究了在0.01mol/L NaOH—0.32％乙二胺—0.05mol/L酒石酸钾钠介质中,锰与4-(2-噻唑偶氮)间苯二酚(TAR)络合吸附波的极谱行为。当介质中含有0.003％TAR时,Mn会产生灵敏的导数极谱波,其峰电位为-0.75V(相对银汞齐电极,下同),方法检出限为1.5×10~(-9)mol/L,线性范围为3.6×1.0~(-9)mol/L～2.7×10~(-6)mol/L。研究了极谱波的性质、机理以及络合物的组成。方法成功地应用于某些植物叶中微量锰的含量测定。     

Complexing Properties of Uranium and Lanthanoids With 4-(2-Thiazolylazo)-6-Chlororesorcinol

Abstract

4-(2-Thiazolylazo)-6-chlororesorcinol (TAR-Cl) reacts sensitively with uranyl(II) and lanthanoids(III), and forms reddish-brown 1:1 and 1:2 complexes. The complexing behaviors were examined spectrophotometrically. The absorption maxima of the complexes are focused near 553 nm and the optimum pH for complexation lies between 6.5–8.8. Beer's law holds up to about 2 × 10^?5 mol 1^?1, with a molar absorptivity of 3.00 × 10⁴ 1 mol^?1 cm^?1 for uranium and 6 × 10⁴ 1 mol^?1 cm^?1 level for each lanthanoid. The absorptivities are increased with the atomic number, especially in light lanthanoids, that are correlative both to the lanthanoid contraction and the basicity of ortho hydroxyl group in the resorcinol ring, but such effects are not clearly recognized in heavy lanthanoids. Effect of masking agents was also examined, and uranium could be determined selectively in the presence of lanthanoid mixtures by the addition of CyDTA.     

2-(2-Thiazolylazo)-p-cresol(TAC) as a Reagent for the Spectrophotometric Determination of Lead(II)

Abstract

The reaction between lead(II) and 2-(2-Thiazolylazo)-p-Cresol(TAC) in the presence of TERGITOL NPX (4 mg/ml) at an apparent pH 9.0–10.0 results in an intensely colored complex which is stable for at least 4 hr.

The composition of the complex is 1:2 cation: TAC and the log of the formation constant is 11.92 ± 0. 40. Beer's law is obeyed up to 6.0μg.ml^?1 of lead(II) at 650nm.

The apparent molar absorptivity at 650 nm is 2.07 × 10⁴ 1. mole^?1.cm^?1 and the detection limit was obtained as 10.0 ng.ml^?1 of lead(II).

The method is applied to determination of lead(II) in copper-base alloy.     

4－（2－氨基噻唑）－间苯二酚为柱前衍化剂液相色谱／电化学检测Fe、Co、Ni

４－（２－氨基噻唑）－间苯二酚为柱前衍化剂液相色谱／电化学检测Ｆｅ、Ｃｏ、Ｎｉ格日勒，李惠梅，李南强，汪尔康（中国科学院长春应用化学研究所电分析化学开放实验室，北京大学化学系，长春，１３００２２）关键词液相色谱，Ｆｅ，Ｃｏ，Ｎｉ，４－（２－氨基噻唑）...     

Lead-Selective Membrane Potentiometric Sensor Based on a Recently Synthesized Bis(Anthraquinone) Sulfide Derivative

Abstract

A new PVC membrane electrode for lead ions, based on bis[(1-hydroxy-9,10-anthraquinone)-2-methyl]sulfide as membrane carrier, was prepared. The sensor exhibits a Nernstian response for Pb²⁺ over a wide concentration range (5.6 × 10^?3-4.0 × 10^?6 M). It has a response time of about 30 s and can be used for at least 3 months without any divergence in potentials. The proposed membrane sensor revealed good selectivities for Pb²⁺ over a wide variety of other metal ions. It was used as an indicator electrode in potentiometric titration of lead ion.     

Potentiometric Studies of Some Bivalent Metal Ion Complexes of a New Ligand,o-(2-Thiazolylazo)-4-Ethylphenol

Abstract

The complexations of a new ligand, o-(2-thiazolylazo)-4-ethylphenol(TAEP) with Ca(II), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hq(II) and Pb(II) have been studied by potentiometric titrations, at 25.0 ± 0.2°C and an ionic strength of 0.1 in 30% v/v dioxane-water mixture. The dissociation constant and spectral data of TAEP and formation constants of the complexes containing various molar ratios of metal ion to ligand, are reported. It is observed that Ca(II) forms only an ML complex in any molar ratios, whereas other metal ions react in two steps forming ML and ML₂ complexes in a 1:3 molar ratio. In the case of 1:1 and 1:2 molar ratios, Mn(II), Co(II), Cd(II) and Hg(II) seemed to form bi- or poly-nuclear complexes because of slightly different formation curves from those of 1:3 molar ratio. The sequence of the first successive formation constant is Cu > Hg > Ni > Pb > Co > Zn > Cd > Mn > Ca, showing Mellor-Maley's order. Further correlation is shown between the formation constants and the second ionization potentials of the metals.     

Copper (II) Sensor Based on a Cephaloridine Antibiotic PVC Matrix

ABSTRACT

A poly (vinyl chloride) (PVC) based membrane of cephaloridine as a novel ionophore exhibits good potentiometric response for Cu²⁺ over a wide concentration range (10^?5-10^? M) with a slope of 28.5 mV per decade. The detection limit is 3.5 × 10^?6 M. The response time of the sensor is < 60 s. The electrode has been used for a period of one month and exhibits good selectivity towards Cu²⁺ in comparison to alkali, alkaline earth, transition and heavy metal ions, with no interference caused by Pb²⁺ Cd²⁺ and Fe²⁺ which are known to interfere with many other copper electrodes. The electrode can be used in the pH range from 4.0 to 6.5 and it can also be used in partially non-aqueous medium having up to 10 (v/v) non aqueous content and in the presence of cationic surfactants at concentrations less than 10^?3 M.     

PVC膜离子选择电极检测下限的优化

价格低廉、携带方便、适用浓度宽、操作简单快捷、能耗低的离子选择电极在医院、分析实验室、野外等领域得到了越来越广泛的应用。尽管如此,由于PVC膜中存在的离子流严重破坏了更低检测下限的获取,限制了离子选择电极的进一步发展。因此,本文从减小甚至消除PVC膜中存在的离子流角度出发,系统论述了优化PVC膜离子选择电极检测下限的原理和优良策略,根据收集归纳的大量数据定量阐述传感膜组成的优化、电极组装和调制、应用旋转电极以及电流极化处理等对检测下限的优化提升作用,进一步总结出各种方法的改善规律,分析它们的优势和面临的问题。提出在PVC铸膜液中要突破传统配方,减小增塑剂和离子交换剂用量,以抑制传感膜两侧的离子流,同时外加电流补偿处理等也是降低电极检测下限的有效方法,对检测下限的改善最好的可降低5个数量级。这一总结为PVC膜离子选择电极的高性能化明确了研究方向。     

新显色剂2-(2-噻唑偶氮)-5-二乙氨基苯甲酸分光光度法测定微量钴

近年来,杂环偶氮苯甲酸类显色剂取得了较快的发展。由于氨基取代结构对试剂性能有较大的影响^[1],因此本文合成了新显色剂2-(2-噻唑偶氮)-5-二乙氨基苯甲酸,(TAEB)并研究了它与钴的显色反应。