Studies on the Zetapotential of Calcite/p-Sulfonato-calix[4,8]arenes

Zeta potential of calixarenes has been reported for the first time. The water-soluble calixarenes has been used as dispersion media in solid/liquid interface. p-sulfonato-calix[4]arene (PSC4) and p-sulfonato-calix[8]arene (PSC8) were synthesized and characterized by FTIR, NMR, mass spectrometry, and HPLC techniques. It was proved that the zeta potential is a fast and simple measurement to know the adsorption behavior of sufonato calixarnes on calcite. The chemisorption of p-sulfonato-calix[n]arene was confirmed by shift in iso electric point, adsorption studies and FTIR. The calculated free energy of adsorption value and its sign suggests the chemical interaction between the calcite surface and p-sulfonato calix[4]and[8]arene.     

Inclusion of Organic Cations by Calix[n]arenes

Calix[n]arenes represent an interestingclass of preorganized aromatic hostsexhibiting an enhanced ability forcation- interaction. Recent resultsobtained with the complexation of variouscalix[n]arenes and five structural typesof organic cations, namely ammonium ions,quaternary ammonium ions, phosphonium ions,iminium ions and tropylium ions are reviewed.The influence of both the guest structure and theshape and flexibility of the hosts on the complexstability in the gas phase and (mainly) in solutionis considered.     

Ion-Selective Electrodes for the Determination of Nitrogen-Containing Medicinal Substances

Stoichiometric ratios and solubility products were determined for medicinal substance–tetraphenyl borate ion pairs. The influence of the nature of the medicinal substance cation incorporated into ionophores and the effect of the solvent–plasticizer on analytical characteristics were studied. The optimal composition of membranes was determined. Ion selective electrodes were used for the potentiometric determination of dimedrol, papaverine, novocaine, and lidocaine in medicinal forms.     

Applications of Ion-Selective Electrodes in Organic Microanalysis: Potentiometric Determination of Organic Cations Precipitated by Tetraphenylborate

Summary Sodium tetraphenylborate has been used in the potentiometric precipitation titration of various water-soluble organic cations, mostly containing a quaternary ammonium moiety. Emf's were monitored with a fluoroborate ion-selective indicator electrode and a double-junction reference electrode. The perchlorate and nitrate electrodes also respond to the various cations. The solid-state cyanide electrode responds to most of the cations investigated. This makes it possible to carry out titrations in partially nonaqueous media. Some of the compounds which can be determined are alkaloids, dyes, and other organic bases.

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Anwendung ionenselektiver Elektroden (ISE) in der organischen Mikroanalyse: potentiometrische Bestimmung organischer Kationen nach Fällung mit Tetraphenylborat

Zusammenfassung Natriumtetraphenylborat wurde zur potentiometrischen Fällungstitration verschiedener wasserlöslicher organischer Kationen verwendet, von denen die meisten einen Rest einer quartären Ammoniumbase enthielten. Die EMK wurde mit Hilfe einer Fluoroborat-ISE und einer double-junction Bezugselektrode gemessen. Perchlorat- und Nitratelektroden eignen sich gleichfalls für verschiedene Kationen. Die Festkörper-Cyanid-Elektrode reagiert mit den meisten der untersuchten Kationen. Infolgedessen kann man die Titrationen in teilweise nicht-wäßrigen Medien durchführen. Zu den analysierbaren Kationen gehören Alkaloide, Farbstoffe u. dgl.

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This paper is dedicated to the memory of my father, Dr. Sigmund Selig, who died in April 1980.

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Work performed under the auspices of the U. S. Department of Energy by the Lawrence Livermore Laboratory under contract number W-7405-ENG-48.     

Ion-Selective Electrodes for the Determination of Antimony and Thallium Based on Water-Insoluble Basic Dye Salts

Abstract

Hexachloroantimonate(V) and tetrachlorothallate(III) salts of Sevron Red L (C.I. Basic Red 17), Sevron Red GL (C.I. 11,085), Flavinduline O (C.I. 50,000) and Phenazinduline O have been applied in liquid-state ion-selective electrodes for the determination of antimony and thallium. The slope of potential versus pM graphs approach full Nernstian response in the range 10 M (Sb) and 10^?6 M (T1) to 10^?2 M. An unusual feature of the electrodes is their response to antimony(III) as well as to antimony(V).     

Ion-Selective Electrodes Based on Bilayer Film Coating

The electrode characteristics of ion-selective electrodes (ISEs) for K⁺, Na⁺, NH₄ ⁺, and Ca²⁺ based on bilayer film coatings, where the inner layer films are electroactive electropolymerized ones and the outer layer films are composed of conventional ion-sensitive materials, have been examined. These ISEs of the coated-wire electrode type have no conventional internal reference solution and reference electrode, but the inner films may be considered to function as the “internal standard solution.” The ion selectivity coefficients and the activity range showing Nernstian response were almost comparable to those of conventional liquid-membrane electrodes. The bilayer-coated ISEs showed insensitivity to O₂ and CO₂, long-term stability, and little drift. It was also found that the electrode performance is practically unchanged after sterilization in an autoclave. The results demonstrate that the bilayer-coated ISEs examined are promising for the determination of K⁺, Na⁺, NH₄ ⁺, or Ca²⁺ activity in biological and environmental systems.     

Determination of Antiseptic Dyes with Ion-Selective Electrodes

The possibility of determining Methylene Blue and Brilliant Green antiseptic dyes in solutions with the use of ion-selective electrodes based on trioctyl oxybenzosulfonic acid was examined. Data on application of the electrodes fabricated to analysis of powdered dyes are presented. A gravimetric method for analysis for Brilliant Green was suggested and used as a comparative technique.     

Synthesis of Ionizable Calix[4]arenes for Chelation of Selected Divalent Cations

Two sets of functionalised calix[4]arenes, either with a 1,3-crown ether bridge or with an open-chain oligo ether moiety in 1,3-position were prepared and further equipped with additional deprotonisable sulfonamide groups to establish chelating systems for selected cations Sr²⁺, Ba²⁺, and Pb²⁺ ions. To improve the complexation behaviour towards these cations, calix[4]arenes with oligo ether groups and modified crowns of different sizes were synthesized. Association constants were determined by UV/Vis titration in acetonitrile using the respective perchlorate salts and logK values between 3.2 and 8.0 were obtained. These findings were supported by the calculation of the binding energies exemplarily for selected complexes with Ba²⁺.     

New Ion-Selective Electrodes for Determination of Bupivacaine and Oxybuprocaine

Abstract

PVC membrane electrodes selective for hydrochlorides of the anaesthetics bupivacaine (BpC) and oxybuprocaine (ObC) are prepared. The electrodes have a near Nernstian slope (58 mV for BpC and 51 mV for ObC electrodes) over the range of 1.6 × 10^?5-10^?1M and 1.3 × 10^?1M for BpC and ObC electrodes, respectively. The change in pH of the test solution within the ranges 2.5–6.0 and 3.0–7.4 does not affect the EpC-and ObC-electrodes, respectively. The electrodes have very long life times (10 days for BpC, and 3 months for ObC) and exhibit good seletivity for the investigated compounds with respect to a large number of inorganic cations and organic substances of biological importance. The isothermal coefficients of the electrodes are calculated from the standard electrode potentials at different temperatures. BpC and ObC are determined successfully in some pharmaceutical preparations using the calibration graph technique and potentiometric titration.     

Lower Rim Substituted tert-Butyl calix[4]arenes (I). The Structure and Complexing Properties in Ion-Selective PVC Membrane Electrodes

Some di- and tetraamide tert-butylcalix[4]areneswere synthesized and described. Their ionophoric properties were studied in liquid membrane ion-selective electrodes. The correlation between thechemical structure (conformation in solution determined by ¹H NMR) and potentiometric ion-selectivity and complex formation constant havebeen studied. The PVC membrane electrodes based on tetraamides 8–11 show high sodium selectivity, are stable and long lasting. Disubstituted amides 1–7 are selective for larger and more lipophilic ions, as for exampleguanidinium ion. The crystal structure of the diamide 4 was determined by single crystal X-ray analysis. Crystals of 4 are triclinic, spacegroup P-1, with: a = 16,669(8), b = 17.795(10), c = 20.984(8) Å, =91.08(4)°, = 91.60(3)°, = 90.73(4)° and Z = 4. Ionophore 4 posseses a distorted cone conformation and is substituted at the proximal phenol rings.     

Multifunctional Calix[4]arenes Containing Pendant Amide and Phosphoryl Groups: Their Use as Extracting Agents and Carriers for Alkali Cations

The complexing, extracting and mobile carrier properties of the tetra(phosphine oxide)-calix[4]arene 1 and the hybrid diamide-di(phosphine oxide)-calix[4]arene 2 were studied. Both ligands give 1 : 1 complexes with alkali cations in THF as shown by the picrate method. 1H NMR experiments were run to follow encapsulation of sodium and potassium cations. The corresponding spectra indicate C2-symmetrical structure. The observed extraction orders of the alkali picrates were as follows K+>Rb+>Li+>Cs+>Na+ for 1 and Li+>Na+>K+>Rb++ for 2. Transport kinetics was analysed by means of a model which assumes pure diffusion and which allows the evaluation of mass transfer coefficients in all systems. These coefficients and their influences on the transport rate are discussed in terms of size of the transporting species in the liquid membrane.     

Urea Biosensors Based on PVC Membrane Ion-Selective Electrodes

Abstract

This paper presents a general method of enzyme immobilization at the surface of ion selective membranes. Covalent binding of enzymes directly on the electrode surface is a very effective method that results in stable enzymatic membranes. As an example the construction of enzymatic sensors for urea determination based on ammonium and hydrogen carbonate ion selective electrodes is presented. The optimum working conditions for these biosensors were found. Bioelectrodes based on an ammonium sensor show very good analytical parameters: dynamic stability - over 2 months without decrease of sensitivity, response time - shorter then 20 s. high sensitivity, determination range from 0.3 to 70 mM. In the contrast to the ammonium ion based biosensors, those constructed on the basis of anion selective electrodes have worse analytical parameters. It is mainly due to poor selectivity and instability of an applied ion selective electrode. In spite of this, both types of urea biosensors were used for measurements in the differential potentiometry mode. The application of such system increased the sensitivity of urea determination.     

Determination of Some Thiobarbiturates with Ion-Selective Membrane Electrodes

Abstract

A liquid membrane Ag⁺-selective electrode of our construction and a commercial solid membrane Ag⁺/S^2--selective electrode were used for the determination of thiobarbiturates by potentiometrie titration with AgNO₃ solution or by direct potentlometry. The potentio-setrio data correlated vd. th IR spectra allowed the elucidation of the reaction mechanism.     

四苯硼酸盐PVC膜锂离子选择电极的研究

四苯硼酸盐与介体溶剂所组成的PVC膜对碱金属离子的选择性同溶剂的性质有关^[1]。因此,可选择适当的溶剂研制碱金属离子选择电极。本工作研究了以DOPP(苯基膦酸二辛酯)或TBP(磷酸三丁酯)为介体溶剂,NaTPB(四苯硼钠)或KTPB(四苯硼钾)为活性物质的PVC膜对金属离子的选择响应。结果表明,DOPP为溶剂、KTPB为活性物质可制备性能良好的PVC膜Li⁺选择电极。该电极的电化学性能接近或优于新近报道的几种Li⁺选择电极^[2~7]。     

Study on Hydrogen Ion-Selective Solid Contact Electrodes Based on Decamethylcyclopentasiloxane

Hydrogen ion-selective solid contact electrode based on decamethylcyclopentasiloxane (DMCS) as ionophore was fabricated. The membrane solution was prepared by mixing DMCS, polyvinyl chloride (PVC), potassium tetrakis p-chlorophenyl borate (KTpClPB) and various plasticizers. The best performance was obtained with the sensor based on NPOE (o-nitrophenyl octyl ether) and the conducting polymer layer of poly(pyrrole), doped with NaClO₄. The electrode exhibited Nernstian-response in the range of pH 1.9–9.8 with a slope of 57.6 ± 0.2 mV per decade and fast response time within 15 s. This electrode showed good selectivity and was successfully used as an indicator electrode in the potentiometric titration.     

Lower Rim Substituted p-tert-Butyl Calix[4]arenes (V). Synthesis of New 5,11,17,22-tetrakis-p-tert-Butyl-25,27-bis(methoxy)- 26,28-bis(dialkoxyphosphorylmethoxy)calix[4]arenes and Cation Complexation Studies in Ion-Selective Membrane Electrodes

The synthesis and characterization of the lower rim bis-phosphorylatedtetrakis-p-tert-butyl-25,27-bis(methoxy)calix[4]arenas(compounds 2–4) is presented. The studied compounds were examined as ionophores in ion-selective membrane electrodes, showing selectivity for rubidium, potassium, and for the large and flat guanidinium cations (G⁺). The correlation wasstudied between the stereochemical structure of the ligands andpotentiometrically determined ion-selectivity. Complex formationconstants in the PVC/BEHS (bis(ethyl)hexyl sebacate) membranes weredetermined. The crystal and molecular structures of compound 4 have been determined by single crystal X-ray diffraction study.     

Conductometric Determination of the Stability Constants of the Inclusion Complexes of Alkali Cations with [22-DD] Diaza Crown Ether, [211] and [221] Cryptands in Acetonitrile

An equilibrium study concerning the association of Na⁺, K⁺, Rb⁺ and Cs⁺ with 4, 7, 13, 18-tetraoxa-1,10-diazabicyclo [8, 5, 5]-eicosane [211], 4, 7, 13, 16, 21-pentaoxa-1, 10-diazabicyclo [8, 8, 5]-tricosane [221] and 4, 13-didecyl-1, 7, 10, 16-tetraoxa-4, 13-diazacyclooctadecane [22-DD] in acetonitrile has been carried out at 25 °C by using a conductometric technique. The observed molar conductivity, Λ, of a test solution was found to decrease significantly for mole ratios less than 1:1 upon the addition of the complexing ligand. A model based on 1:1 stoichiometry has been used to analyze the conductivity data. The data have been fitted according to a non-linear least-squares analysis that provides the stability constant, K, and the molar conductivity, Λ_c, for each cation – ligand inclusion complex. The binding sequences were found to follow the order: Na⁺ > K⁺ > Rb⁺ ≫ Cs⁺ (K ≈ 0) for [211], Na⁺ > K⁺ > Rb⁺ > Cs⁺ for [221] and K⁺ > Na⁺ > Rb⁺ > Cs⁺ for [22-DD] complexes. Trends in ionic conductivities of complexed ions are also discussed.     

Separate Determination of Homologous Sodium Alkyl Sulfates with Ion-Selective Electrodes

The possibility of the separate determination of homologous sodium alkyl sulfates with ion-selective electrodes and using multisensor analysis was studied. The optimum component ratios were found for the analysis of model mixtures with ion-selective electrodes. It was shown that nonlinear regression analysis and artificial neural networks can be used for processing analytical signals from a set of weakly selective sensors for anionic surfactants.     

Determination of Inorganic and Organic Thiophosphates with Ion-Selective Membrane Electrodes

Abstract

The conditions for the determination of sodium thiophosphate and sodium S-(2-amino-ethyl)-thiophos-phate in the presence of phosphate ion using ion-selective membrane electrodes are described. Both thiophosphates (inorganic and organic) are hydrolyzed in acidic medium. The phosphate ion is determined with Pb(II) using a Pb²⁺ – selective membrane electrode.

Cysteamine is determined by potentiometric titration with Hg(I1) using a Ag⁺/S^2? – crystal membrane electrode or by direct potentiometry with a Cu²⁺ selective membrane electrode. The results were verified by the iodination method.     

Determination of β-Lactam Antibiotics by Potentiometry with Ion-Selective Electrodes

Ion-selective electrodes for antibiotics from the penicillin series, with membranes based on three different classes of ionophores (anion exchangers, aza compounds, and metal phthalocyanines), were proposed. The electrochemical and performance characteristics of the sensors were studied and compared.