Selectivity of cyclic polyether type liquid membrane electrodes

Rechnitz, G. A.; Eyal, Ehud.

doi:10.1021/ac60310a025

Cited by 104 publications

(28 citation statements)

References 10 publications

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“…It has been suggested that selectivities of membranes based on macrocyclic polyethers may be approximated by the ratio of the stability constants of the complexes of the respective metals with the given crown compound [6]. Practically, the selectivity of the membrane depends on several factors [7] where the complex partitioning between the membrane and the aqueous phase is the main one.…”

Section: Resuzts and Discussionmentioning

confidence: 99%

Mercury ion‐selective polymeric membrane electrodes based on substituted diaza crown ethers

Brzózka¹,

Pietraszkiewicz

1991

Electroanalysis

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The potentiometric selectivities of membranes based on new N,N'-substituted 4,13-diaza-18-crown-6 ethers were determined under different internal filling electrolytes and conditioning time of the membranes. The preference of Hg2+ over other divalent cations was observed for compounds bearing 2-methylquinolyl or 2-methylquinolyl-1-oxide groups. The membrane electrodes with ionophores 1 and 2 exhibited a linear response in the activity range 10-5-10-3 M Hg(NO&. IilrTRODUCTIONThe past two decades of so-called supramolecular cheniistry have witnessed many interesting syntheses of the ionophores useful in the membrane ion-selective electrodes, or ISFET-transistors. The need for environmental pollution monitoring prompted development of lipophilic thiacrown ether derivatives as heaq-metal ionselective ionophores [ 1-21, We have recently demonstrated the synthesis of the two diaza-crown ethers incorporating 2-quinolylmethyl and 2-quinolylmethyl-1-oxide units, which possess preference Hg"-selectivity over other divalent cations by means of PVC-membrane technique [ 3 ] .This article shows Hg(I1)-response of the PVC membrane electrodes based on substituted diaza-crown ethers, and their potentiometric selectivities under various measurement conditions. EXPERIMEWM ChemicalsAll of the metal salts employed here were analytical grade and were purchased from POCh Gliwice, Poland. Standard solutions (0.1 M) of metal salts in redistilled water were prepared; working solutions were prepared as required by suitable dilution with redistilled water. Membrane PreparationThe composition of the membrane was 1% m/m ionophore, 30% m/m PVC, 70 mol-% KTp-CIPB (with respect to the ionophore), and 68-69% m/m o-NPOE as plasticizer. The membrane preparation was described earlier [4].The electrodes were left overnight in conditioning solution, e.g., redistilled water, aqueous solutions of KCl, CuCl,, or HgCI,. Two electrodes were prepared for each composition of membrane. Emf Measurements

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Section: Resuzts and Discussionmentioning

confidence: 99%

Mercury ion‐selective polymeric membrane electrodes based on substituted diaza crown ethers

Brzózka¹,

Pietraszkiewicz

1991

Electroanalysis

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“…This model is also supported by the work of Ciani, Eisenman and Szabo 17 on the actins. By measuring the potentiometric selectivities of the valinomycin electrode and the formation constants of the valinomycin--cation complexes, it was possible to show that the selectivity coefficient is approximately equal to the formation constant quotient for various pairs of alkali metal ions; in thick electrode membranes similar results were also obtained when cyclic polyethers were used as carriers 44 .…”

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confidence: 70%

Mechanistic aspects of ion-sensitive membrane electrodes. A subjective view

Rechnitz¹

1973

Pure and Applied Chemistry

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“…The recovery of barium as a complex with DCH18C6 and the interfering effects of alkali and alkaline earth elements on the recovery of barium depend on the stability constants (on a scale) of corresponding metal complexes [32]:…”

Section: Resultsmentioning

confidence: 99%

Chemical Mechanism of the Solid-Phase Extraction of Metal Complexes: Barium Complexes with Crown Ethers

et al. 2005

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Solid-phase extraction (SPE) is commonly used for the preconcentration of trace metals in the analysis of various materials. Previously, we studied the SPE of heavy [1] and platinum-group metals as neutral chelates [2] and of radionuclides as coordinatively solvated compounds [3,4] and mixed complexes [5] by alkylated silica gels. Methods based on the formation of ion associates are also successfully used. Methods for the separation of 90 Sr [6], 137 Cs, 144 Ce, 60 Co, 214 Bi, and 210 Po [7] were developed using the dicyclohexano-18-crown-6-sodium dodecylsulfonate (DCH18C6-NaDDS) system.The aim of this work was to study the chemical mechanism of the SPE of barium complexes formed in the DCH18C6-NaDDS and dibenzo-18-crown-6 (DB18C6-NaDDS) systems and to discuss the chemical mechanism of the SPE of various ion-associate complexes formed by charged metal complexes based on a comparison and analysis of the experimental results and published data. EXPERIMENTALStarting substances. The following reagents were used: DCH18C6, DB18C6, sodium dodecylsulfonate, and methanol. The following reagents were of chemically pure grade: Ba(NO 3 ) 2 , Ca(NO 3 ) 2 · 4H 2 O, KNO 3 , Mg(NO 3 ) 2 · 6H 2 O, NaNO 3 , HNO 3 , HCl, and NaOH. The following stock solutions of the reagents were prepared: aqueous solutions of the above salts of alkali and alkaline earth metals, an aqueous 0.1 M sodium dodecylsulfonate solution, and alcoholic 0.1 M solutions of the macrocyclic compounds.Adsorbents. Alkylated silica gel with C 16 hydrocarbon radicals, a Diasorb C 16 adsorbent (particle size of 40-160 µ m; carbon content of 14.7%), and commercial Diapak C 16 cartridges with the above adsorbent from BioKhimMak (Moscow State University, Russia) were used as adsorbents. The adsorbent volume in a cartridge was 1 mL. According to certified data, the specific surface area of the C 16 adsorbent used in this study was equal to 300 ± 30 m 2 /g, and the density of grafting of alkyl groups was no lower than 3.3 µ mol/g [8]. The adsorbent was prepared for operations in accordance with a published procedure [9]. To prepare a modified adsorbent, 5 mL of ethanol was initially passed through a Diapak ë 16 cartridge using a peristaltic pump. Next, 10 mL of a reagent solution ( c DCH18C6 = c NaDDS = 1 × 10 -2 M) and 5 mL of water (for the removal of an excess of the reagents) were passed. A Diapak-nitrile adsorbent with the terminal nitrile group was also used (particle size of 40-160 µ m; carbon content of 4.55%).Procedure. The extraction of barium was studied under both static and dynamic conditions. In the former case, a solution with a certain metal concentration and reagent solutions with corresponding values of pH were added to a weighed portion of the C 16 adsorbent pretreated with methanol. The solution with the adsorbent was shaken for a time required for reaching a constant value of metal recovery; thereafter, the adsorbent was filtered off. In the study of adsorption under dynamic conditions, the test solution was pumped through a Diapak C 16 cartridge a...

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Selectivity of cyclic polyether type liquid membrane electrodes

Cited by 104 publications

References 10 publications

Mercury ion‐selective polymeric membrane electrodes based on substituted diaza crown ethers

Mercury ion‐selective polymeric membrane electrodes based on substituted diaza crown ethers

Mechanistic aspects of ion-sensitive membrane electrodes. A subjective view

Chemical Mechanism of the Solid-Phase Extraction of Metal Complexes: Barium Complexes with Crown Ethers

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