Reproterol plastic membrane ion-selective electrodes based on its individual and mixed ion-exchangers with phosphotungstic and/or phosphomolybdic acids

Reproterol hydrochloride (RpCl), selective PVC membranes based on ion associates of reproterolium-phosphotungstate (Rp-PTA); reproterolium-phospho-molybdate (Rp-PMA) or a mixture of both (Rp-PTA/PMA) were prepared. The electrodes displayed a linear response over the concentration range of 6.3×10⁻⁶–1.0×10⁻¹ mol dm⁻³ RpCl. The working pH ranges of the above electrodes were 2.5–9.0, 2.5–8.5 and 2.0–9.0 and their isothermal temperature coefficients were 0.00014, 0.00090 and 0.00103 V/°C, respectively. The electrodes showed good selectivity to the reproterolium ion with respect to many inorganic cations, sugars and amino acids. The standard additions and potentiometric titration methods were used to determine RpCl in pure solutions and in its pharmaceutical preparations with high accuracy and precision.     

Hydralazine-selective PVC membrane electrode based on hydralazinium tetraphenylborate

A hydralazine ion-selective PVC membrane electrode based on hydralazinium tetraphenylborate has been prepared with dioctyl phthalate as plasticizer. The electrode showed linear response with a slope factor of 57.5 mV/concentration decade at 20 degrees over the concentration range from 4 x 10(-4) to 10(-1)M hydralazine. The effects, on the electrode performance, of membrane composition, pH of the test solution and the time of soaking were studied. The electrode exhibited good selectivity for hydralazine with respect to a large number of inorganic cations and organic substances of biological importance. The standard-addition method and potentiometric titrations were used to determine hydralazine concentrations in pure solutions and in a pharmaceutical preparation, with satisfactory results.     

Potassium ion-selective electrodes based on valinomycin/PVC overlayered solid substrates

In this work, permutations of plasticized PVC membranes with incorporated valinomycin are coated over various substrate metallizations. Characterization of the resulting potassium electrodes includes measurement of sensitivity, short- and long-term potential drift, dissolved oxygen induced potential transients and probe lifetime. Results using the best performing metallizations compare favorably with those obtained using identical membranes in the symmetrical solution contact configuration. Prospects for use of this approach as the ion-sensing layer of ISFET (Ion-Sensitive Field-Effect Transistor) devices are considered.     

Guanidinium-selective PVC membrane electrodes based on crown ethers

Guanidinium-selective membrane electrodes were constructed with dibenzo-24-crown-8, dibenzo-27-crown-9, tribenzo-27-crown-9 or dibenzo-30-crown-10. The detection limits and selectivity coefficients towards different interfering ions, such as Li⁺, Na⁺, K⁺, NH⁺₄, Mg²⁺ and Ca²⁺ were determined. The electrode with dibenzo-27-crown-9 shows linear response over the range 10^?1–10^?4 M, with selectivity coefficients about 10^?2 for most alkali and alkaline earth metal ions.     

Coated-wire organic ion-selective electrodes in titrations based on ion-pair formation : Determination of arenediazonium salts with sodium tetraphenylborate

Titrimetric determinations of arenediazonium salts can be based on ion-pair formation between the diazonium cation and tetraphenylborate. Titrations are done under cooling with ice and are followed potentiometrically with organic ion-selective electrodes comprising PVC membranes plasticized with polar solvents and coated on aluminium wires. The method was tested in determinations of arenediazonium salts derived from 20 aromatic amines, including aniline, toluidines, naphthylamines and their derivatives. Except for compounds containing hydrophylic groups such as —COOH and —OH, the potentiometric titration curves have well defined end-points. The results are reproducible, with relative standard deviations in the range 0.4–1.4% at the millimolar level. The method can be used for reliable determinations of arenediazonium salts in analytical control of azo dyestuff production.     

Potassium ion-selective membrane electrodes based on naphtho-15-crown-5

The potassium-selective PVC membrane electrodes based on naphtho-15-crown-5 have rapid, stable and Nernstian response in the range 10^-1–10^-5 M. The selectivity coefficient for potassium over sodium is 4 × 10^-4.     

Hydrogen ion-selective membrane electrodes based on alkyldibenzylamines as neutral carriers

New synthetic hydrogen ion-selective carriers, derivatives of dibenzylamine, have been used as neutral carriers in liquid membrane electrodes to measure pH range from 2 to 10. A H(+)-selective membrane electrode based on octyldibenzylamine gave a better linear response to pH than other alkyldibenzylamines as neutral carriers. It gave a linear response over the pH range 2-10 and a slope of 56.5 mV/pH at 20 degrees C. The electrode had fairly low electrical resistance, good potential stability and reproducibility. The selectivity coefficients towards sodium, potassium and calcium ions as well as other characteristics of the membrane electrode have been studied.     

Determination of sulpha-drugs with ion-selective membrane electrodes

A liquid-membrane mercury(II)-sensitive electrode is used for determination of various sulpha drugs by addition of excess of mercuric nitrate and potentiometric back-titration of the surplus mercury(II) with EDTA. The performance of the electrode is compared with that of an Ag(2)S crystal-membrane electrode. Attempts to prepare a sulphamethoxazole-sensitive electrode failed.     

Solvent polymeric membrane ion-selective electrodes

The significant role of poly(vinyl chloride) as a support polymer in solvent polymeric ion-selective electrodes is briefly reviewed. This lays emphasis on the way PVC has contributed to the relatively high state of development of conventional ion-selective electrodes, microelectrodes, coated-wire electrodes and ion-sensitive field effect transistors based on liquid ion-exchanger and neutral carrier ionophore sensors. Also discussed are possibilities of using alternative polymer matrices for overcoming some of the shortfalls of the PVC electrodes.     

Bio-sensors based on ion-selective electrodes

Summary A review is given on bio-sensors based on ion-selective electrodes. By means of several examples of enzyme electrodes the salient features and the operating principles of the new sensors are illustrated. 72 literature references.

---

Biosensoren auf der Grundlage von ionenselektiven Elektroden

Zusammenfassung Ein Überblick über Biosensoren wird gegeben. An Hand mehrerer Beispiele von Enzymelektroden werden die entscheidenden Eigenschaften und die prinzipielle Arbeitsweise dieser neuen Sensoren dargestellt. 72 Literaturzitate.

     

Electrochemical studies on ion-selective polymer membrane electrodes

The selectivity and response of neutral carrier based polymer membrane electrodes are investigated via exchange current measurements for systems containing valinomycin, dibenzo-18-crown-6, and plasticizer alone in a polyvinyl chloride matrix. Using a transient galvanostatic step method, apparent exchange current densities of 1.3 X 10^?3 A/cm², 5.4 X 10^?6 A/cm², and 2.2 X 10^?9 A/cm² were obtained with K⁺ as the primary ion for the three types of membranes, respectively. Preliminary results indicate that the exchange current data obtained with this technique are complementary to the potentiometric response observed for the membranes studied.     

功能高分子膜离子选择电极研究VI.压片PVC膜氯离子选择电极的暂态极化行为

Both fast triangle-wave potential sweep method and fast square-wave potential sweep method have been applied to study transient behavior of the functional polymer membrane chloride electrode. On the basis of current-time curve and potential-time curve, the electrochem. parameters of the electrode were calculated successfully under various conditions. The characterization of the level of ion transfer has been made by means of electrochem. polarization resistance Rr which is related not only to the membrane composition and its shape (area etc.), but also to concentration of the chloride ions in solution The Rr values calculated from both methods are the same. Cl- in the concentration range of 10-4-10-1 mol/L showed linear relation between i and log c, where c is the concentration The slope is proportional to the membrane area.     

Lead ion-selective membrane electrodes based on some recently synthesized 9,10-anthraquinone derivatives

Four different 9,10-anthraquinone derivatives were studied to characterize their abilities as lead ion carrier in PVC membrane electrodes. The electrode based on 1,8-dihydroxy-2,7-bis(prop-2′-enyl)-9,10-anthraquinone exhibits a Nernstian response for Pb²⁺ ions over a wide concentration range (2.0×10⁻³–2.0×10⁻⁶ M). The response time of the sensor is 30 s and the membrane can be used for more than four months without observing any deviation. The electrode revealed comparatively good selectivities with respect to alkali, alkaline earth and some transition and heavy metal ions. It was used as an indicator electrode in potentiometric titration of sulfate ions with a lead ion solution.     

离子缔合型离子选择电极的研究 I: PVC膜铬(VI)离子选择电极的研制的和应用

A new Cr(VI)-selective electrode of PVC membrane based on triheptyl dodecyl ammonium iodide is described. The response of the electrode is Nernstian for Cr(VI) concentration down to 2X10-6M in 0.03-0.13N HF solution. Limit of detection is 5X10-7M. The plot of logarithms of selectivity coefficients vs. z/γ of various anions is essentially linear with a correlation coefficient of -- 0.88. Applications of the electrode in determination of total Cr in steels and copper alloys, and Cr(VI) in waste-water from chromium electroplating are reported.     

Ionic liquids promote selective responses towards the highly hydrophilic anion sulfate in PVC membrane ion-selective electrodes

A remarkable enhanced response towards the hydrophilic anion sulfate using plasticized PVC membranes containing the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate and a polyazacycloalkane derivative as ionophore has been found.     

Potentiometric titration of organic cations with sodium tetraphenylborate and a liquid-membrane tetraphenylborate ion-selective electrode

Simple potentiometric titrations are described for the determination of various organic cations (usually 5–25 μ mol) with 0.01 M sodium tetraphenylborate. A liquid-membrane electrode with tetrapentylammonium tetraphenyiborate dissolved in 4-nitro-m-xylene as liquid ion-exchanger is used successfully in the semi-automatic titration of quaternary ammonium compounds, cationic surfactants, alkaloids and other substances of pharmaceutical importance which are precipitated by tetraphenyiborate. Analysis of pharmaceutical preparations gave satisfactory results.     

新型中性载体PVC膜高选择性硫氰酸根电极研究

研究了新型Schiff碱对溴苯甲醛缩邻氨基酚过渡金属配合物的阴离子响应行为。实验结果表明:以Cu(Ⅱ)配合物为载体的电极对硫氰酸根具有优良的电位响应性能(pH4.0),电极的线性范围为1.0×10-1～2.0×10-5mol/L,斜率为-59.4mV/dec,检出限为9.0×10-6mol/L。其反Hofmeister选择性次序为:SCN->Sal->I->ClO4->NO2->NO3->Br->SO42->Cl-,研究了阴离子与载体的作用机理,结果表明SCN-与载体中铜原子直接作用。电极可应用于废水及人体唾液中SCN-的测定。