• Journal of the Korean Chemical Society
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• v.39 no.9
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• pp.698-704
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• 1995

The ion-selective membrane fabricated with 33 wt% PVC, 66 wt% o-NPOE and 1 wt% 4'-benzothiazolylbenzo-15-crown-5 (TB15C5) as a neutral carrier exhibited an enhanced selectivity to potassium ion over sodium ion compared to those prepared with other 15-crown-5 or 18-crown-6 derivatives. The potentiometric properties (response slope, selectivity, detection limits and lifetime) of TB15C5-based ISE membranes along with those based on valinomycin, benzo-15-crown-5 (B15C5), 4'-aminobenzo-15-crouwn-5 (AB15C5), benzo-18-crown-6 (B18C6), dibenzo-18-crown-6 (DB18C6) and bis[(benzo-15-crown-5)-4'-ylmethyl]pimelate (PI-Ⅱ) ionophores were carefully examined under the same experimental conditions. The enhanced selectivity of TB15C5-based membrane to potassium is explained in terms of the effect of the benzothiazol functional group and the distribution coefficients of metal ions.

• Journal of the Korean Chemical Society
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• v.35 no.1
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• pp.51-58
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• 1991

A new tubular poly(vinyl chloride) membrane type of nitrate selective electrode was prepared and its characteristics were evaluated. The response slope, detection limit, and response time (t$_{99}$) under the optimum membrane composition (5${\%}$ aliquat-NO$_3$ solution + 32${\%}$ poly(vinyl chloride) + 63${\%}$ dibutyl sebecate) of the electrode were 58.5 ${\pm}$ 0.1 mV/decade, 2.0 ${\times}$ 10$^{-5}$ M, and 25 seconds, respectively. The nitrite ion was determined by the continuous-automated method using the new electrode. 10$^{-2}$ M phosphate buffer solution (pH 7.6) was used as a recipient solution. And also hydrogen peroxide (0.3${\%}$) was added to the recipient as an oxidant. The linear response range and response range and response slope for the standard nitrite solution under the optimum condition of this electrode system were 8.0 ${\times}$ 10$^{-5}$ M ∼ 5.0 ${\times}$ 10$^{-2}$ M and 56.8 ${\pm}$ 0.2 mV/decade, respectively.

• Bulletin of the Korean Chemical Society
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• v.27 no.9
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• pp.1418-1422
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• 2006

In this work the construction of a novel poly(vinyl chloride) membrane sensor based on 2,2'-dianiline disulfide (DADS) as a neutral carrier, o-nitrophenyloctyl ether (NPOE) as a plasticizer and sodium tetraphenyl borate (NaTPB) as an anionic site with unique selectivity towards Tm(III) ions is reported. The electrode has a linear dynamic range between $1.0\;{\times}\;10^{-6}$ and $1.0\;{\times}\;10^{-2}$ M, with a nice Nernstian slope of 19.5 ${\pm}$ 0.3 mV per decade and a detection limit of $4.0\;{\times}\;10^{-7}$ M at the pH range of 4.8-8.5. It has a very fast response time (<15 s) in the whole concentration range, and can be used for at least 4 weeks without any considerable divergence in the electrode potentials. The proposed sensor revealed comparatively good selectivity with respect to most common metal ions, and especially lanthanide ions. It was used as an indicator electrode in the potentiometric titration of Tm(III) ions with EDTA and in direct determination of concentration of Tm(III) ions in binary mixtures. It was also applied in determination of fluoride ions in mouth wash preparations.

• Journal of Sensor Science and Technology
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• v.27 no.2
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• pp.69-75
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• 2018

In this study, we propose a multichannel interdigitated capacitor (IDC) sensor for detecting the bitterness of coffee. The operating principle of the device is based on the variation in capacitance of a sensing membrane in contact with a bitter solution. Four solvatochromic dyes, namely, Nile red, Reichardt's dye, auramine-O, and rhodamine-B, were mixed with polyvinylchloride (PVC) and N,N-dimethylacetamide (DMAC), to create four different types of bitter-sensitive solutions. These solutions were then individually inserted into four interdigitated electrodes (IDEs) using a spin coater, to prepare four distinct IDC sensors. The sensors are capable of detecting bitterness-inducing chemical compounds in any solution, at concentrations of approximately $1{\mu}M$ to 1 M. The sensitivity of the IDC bitterness sensor containing the Reichardt's dye sensing-membrane was approximately 1.58 nF/decade. The multichannel sensor has a response time of approximately 6 s, and an approximate recovery time of 5 s. The proposed sensor offers a stable sensing response and linear sensing performance over a wide measurement range, with a correlation coefficient ($R^2$) of approximately 0.972.

• Bulletin of the Korean Chemical Society
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• v.24 no.12
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• pp.1737-1741
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• 2003

Azo-functionalized calix[4]arenes as ionophores for chloride-selective electrode, 5,11,17,23-Tetra-tert-butyl-25,27-bis[(N,N-dimethyl-aniline-azo-phenylthioureido)ethyl]oxy-26,28-dihydroxycalix[4]arene (4a) and 5,11,17,23-Tetra-tert-butyl-25,27-bis[(N,N-dimethyl-aniline-azo-phenylthioureido)ethyl]oxy-26,28-dimethoxycalix[4]arene (4b) were synthesized. The PVC membrane electrode based on azo-functionalized calix[4]arene 4a with o-NPOE exhibits a linear stable response over a wide concentration range ($1.5{\times}10^{-4}-1.0{\times}10^{-1}$) with a slope of -52.0 mV/decade and a detection limit of log[$Cl^-$] = -4.02. This ionophore-based membrane exhibited improved selectivity for chloride anion compared with classical Hofmeister series.

• Bulletin of the Korean Chemical Society
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• v.14 no.1
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• pp.123-127
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• 1993

New lipophilic Crown-4 compounds of 16-membered rings containing furan (neutral carrier,I), tetrahydrofuran (neutral carrier,II) and lithium complex of the latter (neutral carrier,III) have been synthesized and tested as the active sensors for lithium ion in poly(vinyl chloride) (PVC) membrane electrode, in the presence and absence of an anion excluder, tetrakis(4-chloro-phenyl)borate (KTClPB), 2-nitrophenyl phenyl ether (NPPE), tris(2-ethylhexyl)phosphate (TEHP), o-nitrophenyl octyl ether (NPOE), dioctyl adipate (DOA), bis(2-ethylhexyl)adipate (BEHA), di-n-octylphenyl phosphonate (DOPP) were used as plasticizing solvent mediators. The electrode response function had a nearly Nernstian slope of 54-61 mV per decade (25$^{\circ}$C) within the concentration range of $10^{-1}-10^{-4}$ M LiCl and the detection limits for all electrodes were ca. $5{\times}10^{-4}$ M. The response time of the electrode was faster at the higher lithium concentration and the response of the electrode was stable for longer than 6 months. The sensor membranes exhibit improved response times and increased lifetimes as compared to the system described earlier.

• Membrane Journal
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• v.9 no.4
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• pp.230-239
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• 1999

Perchlorate ion-selective electrodes in PVC membranes that respond linearly to concentration 106 M were developed by incorporating the quaternary phosphonium salts as a canier. The effects of the chemical structure, the contents of canier, the kind of plasticizer and the membrane thickness on electrode characteristics such as the electrode slope, the linear respone range and the detection limit were studied. With this results, the detectable pH range, selectivity coefficients and AC impedance characteristics were compared and investigated. The perchlorate ion substituents of the quaternary phosphonium salts like tetraoctylphosphonium perchlorate (TOPP) , tetraphenylphosphonium perchlorate(TPPP), and tetrabutylphosphonium perchlorate(TBPP) as a canier were used. The electrode characteristics were better in the ascending order of TBPP < TPPP < TOPP, with the increase of carbon chain length of the alkyl group. Dioctylsebacate(OOS) was best as a plasticizer, the canier contents were better with 11.76 wt% and the optimum membrane thickness was 0.19 mm. Under the above condition, the electrode slope was 56.58 mV/$^P{ClO}_4$,the linear response range was $10^{-1}$\times$10^{-6}$ M, the detection limit was 9.66 x $10^{-7}$ M. The performance of electrode was better than Orion electrode. The electrode potential was stable within the pH range from 3 to 11. The order of the selectivity coefficients for the perchlorate ion was sol < F < Br < 1. With the result of impedance spectrum, it was found that the equivalent circuit for the electrode could be expressed by a series combination of solution resistance, parallel circuit consisting of the double layer capacitance and bulk resistance and Warburg impedance. And solution resistance was almost not appeared and Warburg impedance was highly appeared by diffusion. Then Warburg coefficient was 1.32$\times$$10^74 $\Omega$ $\cdot$ ${cm}^2/s^{1/2}$.

• BMB Reports
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• v.31 no.3
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• pp.296-302
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• 1998

A potentiometric flow injection biosensor for the analysis of anti-cholinesterases (anti-ChEs), based on inhibition of enzyme activity, was developed. The sensor system consists of a reactor with acetylcholinesterase (AChE) immobilized on controlled pore glass and a detector with an $H^{+}-selective$ PVC-based membrane electrode. The principle of the analysis is based on the fact that the degree of inhibition of AChE by an anti-ChE is dependent on the concentration of the anti-ChE in contact with AChE. The sensor system was optimized by changing systematically the operating parameters of the sensor to evaluate the effect of the changes on sensor response to ACh. The optimized biosensor was applied to the analysis of paraoxon, an organophosphorus pesticide. Treatment of the inhibited enzyme with pyridine-2-aldoxime fully restored the enzyme activity allowing repeated use of the sensor.

• Journal of the Korean Chemical Society
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• v.32 no.5
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• pp.409-415
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• 1988

In this study, an aniline modified Bakelite-A resine was synthesized by polymerizing phenol, formaldehyde and aniline. Structural properties of the polymer were examined by IR spectroscopy, elemental analysis and vapour pressure osmometry. By visible spectroscopy, it was found that nitrogens of amine groups in the polymer are strongly coordinated to Ni(Ⅱ). Also a nitrate ion-selective PVC membrane electrode based on the polymer-Ni(Ⅱ) complex as ion carrier was preparaed. The electrode gave a linear response with a Nernstian slope within the concentration range $10^{-1}$ M∼$10^{-4}$M $KNO_3$.

• Analytical Science and Technology
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• v.8 no.1
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• pp.79-84
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• 1995

Ion-selective poly(vinyl chloride) membrane electrodes for the determination of the anticholinergic drug alverine in pure substances is described. Ion-pair complex of alverine with anionic counter ion acid red 97 is investigated as electroactive compound for the electrode membrane. On the optimal composition of membrane, its slope was 55.35mV/decade, relative standard deviation was 0.61 and lower limit of linear range was $1.0{\times}10^{-5}M$. The observed potentiometric selectivity coefficient was -2.625 toward methylephedrine and -2.216 toward histidine. We can got the stable potential at pH 7.0~4.0. Response time was 20~30 seconds for solutions${\leq}10^{-4}M$, about 10 seconds for solutions ${\geq}10^{-4}M$ of these compounds.