Evaluation of the optimum composition of neutral-carrier membrane electrodes with incorporated cation-exchanger sites

Meier, P C; Morf, Werner E.; Läubli, Markus W.; Simon, W.

doi:10.1016/s0003-2670(00)85531-2

Cited by 162 publications

(87 citation statements)

References 16 publications

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“…[24][25][26] Since the widely used uncharged carriers are neutral when uncomplexed and the complexes have the same charge as the analyte ion, the respective membranes require the additional incorporation of lipophilic ions of opposite charge to obtain a Nernstian response, 27-29 a decrease in the membrane resistance, 30 a reduction in the coion interferences, 31 and an improvement in the detection limit and optimization of the selectivity. [32][33][34] In practice, alkali salts of tetraphenylborate derivatives are used for cationic-selective membranes and tetraalkylammonium salts for anion-selective membranes. The incorporation of ionic sites into the membrane is also beneficial for charged carrierbased ISEs.…”

Section: Potentiometric Response Characteristics Of Electrodesmentioning

confidence: 99%

Potentiometric Membrane Electrode for Salicylate Based on an Organotin Complex with a Salicylal Schiff Base of Amino Acid

Xu¹,

Yuan²,

Fu³

2005

ANAL. SCI.

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Section: Potentiometric Response Characteristics Of Electrodesmentioning

confidence: 99%

Potentiometric Membrane Electrode for Salicylate Based on an Organotin Complex with a Salicylal Schiff Base of Amino Acid

Xu¹,

Yuan²,

Fu³

2005

ANAL. SCI.

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“…18,19 These lipophilic anionic sites can help reduce membrane resistance and limit the interference from anions at high sample activities. In addition, by influencing the concentration of free carrier available for complexing cations, they can also improve the selectivities of the ISEs.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, by influencing the concentration of free carrier available for complexing cations, they can also improve the selectivities of the ISEs. 18 The optimum concentration of such lipophilic additives in the membrane phase is dependent in part on the charge of the primary ion and its complexation stoichiometry with the carrier as compared to that of the interfering ion. 19 To optimize the potentiometric selectivity of BCE-based liquid-polymeric membrane electrodes toward the potassium ion, different membrane compositions were prepared.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Evaluation of a Bis(crown ether) Ionophore with a Conformationally Constrained Bridge in Ion-Selective Electrodes

et al. 1998

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There has been a recent rapid growth in the development of chemical sensors because of the demand for simple analytical techniques that can provide continuous monitoring of analytes in a variety of matrices. [1][2][3] In the area of membrane-based ion-selective electrodes (ISEs), special emphasis has been placed on the composition of the membrane phase and on the development of new ionophores, aiming at enhancing the potentiometric response characteristics (e.g., selectivity, sensitivity, linear range and lifetime) of the ISEs.The majority of cation-selective electrodes are based on neutral carrier ionophores. In particular, the antibiotic valinomycin has proved to be an excellent ionophore in potassium-selective liquid-polymeric membrane electrodes. 4 In addition to valinomycin, several other ionophores have been used in the preparation of potassium ISEs. 5-8 Among these, bis(crown ethers) with two 15-crown-5 ethers attached via a bridge [7][8][9][10] exhibit a favorable potassium binding over sodium due to the formation of sandwich-type complexes with potassium.9,10 The observed selectivities of ISEs prepared with bis(15-crown-5 ethers) are sometimes comparable to those obtained by using valinomycin as the ionophore. 5Bis(crown ethers) can be prepared with functional groups that allow their covalent attachment on polymer matrices. This is an advantage when designing ISEs with extended lifetimes because covalent attachment of the ionophore precludes its leaching from the polymer membrane phase to the aqueous phase. 11-13 Direct attachment of a bis(crown ether) to a polymer backbone, however, may restrict the free movement of the ionophore or pose serious steric problems with the backbone of the polymer, which could lead to worsening of the response.7,14 A long flexible chain connecting the bis(crown ether) and the polymer could provide a solution to this problem. In this paper, we report on the synthesis and evaluation of a new bis(crown ether) (BCE) ionophore with a long and flexible side chain, which can serve as a precursor for the chemical immobilization to a polymer backbone. Another feature of the designed ionophore is the incorporation of a conformationally constrained bridge (an isophthalic acid derivative) between the two crown ether moieties. This isophthalic acid derivative allows each of the crown ether macrocycles to be in a parallel alignment with each other during complexation, which helps maximize their interaction with the analyte ion. ExperimentalReagents 5-Nitroisophthalic acid, 4-nitrobenzo-15-crown-5, 10% Pd/C, 97% thionyl chloride, triethylamine, aluminum oxide (neutral, Brockmann I), and stearoyl chloride were all obtained from Aldrich (Milwaukee, WI). Selectophore-grade tetrahydrofuran (THF), 2-nitrophenyloctyl ether (NPOE), tris(2-ethylhexyl)phosphate (TOP), bis(2-ethylhexyl) sebacate (DOS), bis(1- A new bis(crown ether) ionophore containing two benzo-15-crown-5 moieties connected with each other via a conformationally constrained bridge attached to a C18-lipophilic side chain was desig...

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“…In the case of sensors based on neutral ionophores, these ionic sites with a charge sign opposite to that of the primary ion are necessary for the sensor to give the Nernstian response [25][26][27][28]. Also, these lipophilic excluders help to reduce the membrane resistance [29], improve the selectivity [30][31][32] and reduce interference from sample anions [33,34]. However, in the case of charged carrier-based sensors, the charge sign of the ionic sites that gives the highest potentiometric selectivities depends on the charge of the ionophore and that of the primary and interfering ions [28].…”

Section: Effect Of Plasticizers and Ionophore Compositionsmentioning

confidence: 99%

A PVC plasticized membrane sensor for nickel ions

et al. 2006

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Abstract.A new PVC membrane sensor, which is highly selective towards Ni (II) ions, has been developed using a thiophene-derivative Schiff base as the ionophore. The best performance was exhibited by the membrane having the composition percentage ratio of 5:3:61:31 (ionophore:NaTPB:DBP:PVC) (w=w), where NaTPB is the anion excluder, sodium tetraphenylborate and DBP is the plasticizing agent (dibutyl phthalate). The membrane exhibited a good Nernstian response for nickel ions over the concentration range of 1.0Â10 À1 -5.0Â10 À6 M (limit of detection is 1.8Â10 À6 M) with a slope of 29.5 AE 1.0 mV per decade of activity. It has a fast response time of <20 s and can be used for a period of 4 months with good reproducibility. The sensor is suitable for use in aqueous solutions of a wide pH range of 3.2-7.9. The sensor shows high selectivity to nickel ions over a large number of mono-, bi-and trivalent cations. It has been successfully used as an indicator electrode in the potentiometric titration of nickel ions against EDTA and also for direct determination of nickel content in real samples -wastewater samples from electroplating industries and Indian chocolates.

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Evaluation of the optimum composition of neutral-carrier membrane electrodes with incorporated cation-exchanger sites

Cited by 162 publications

References 16 publications

Potentiometric Membrane Electrode for Salicylate Based on an Organotin Complex with a Salicylal Schiff Base of Amino Acid

Potentiometric Membrane Electrode for Salicylate Based on an Organotin Complex with a Salicylal Schiff Base of Amino Acid

Synthesis and Evaluation of a Bis(crown ether) Ionophore with a Conformationally Constrained Bridge in Ion-Selective Electrodes

A PVC plasticized membrane sensor for nickel ions

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