• Bulletin of the Korean Chemical Society
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• v.19 no.2
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• pp.207-211
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• 1998

Potentiometric characteristics of DOS plasticized PVC-based membranes containing upper-rim calix[4]crown neutral carrier to various metal cations and protonated alkylamines have been examined. Although the calix[4]crown-based membrane electrodes exhibited substantial emf responses to alkali and alkaline earth metal cations, their high detection limits (- log[Cs+]=4.5) and sub-Nernstian response slopes (48 mV/pCs+) to the most selective cation, cesium, indicate that the metal cation complexing ability of calix[4]crown is much weaker than that of macrocyclic crown ethers. However, the calix[4]crown-based membrane electrodes exhibited near-Nernstian response slopes (56 mV/decade for hexylNH3+) with low detection limits (log[hexylNH3+]= - 6.7) to most alkylammonium ions compared to those of blank (DOS plasticized PVC membrane with no ionophore) or crown ether-based membranes. While the selectivity patterns of blank and crown ether-based membranes are determined primarily by the lipophilicity of alkylammonium ions, the membranes doped with calix[4]crown ionophore could effectively discriminate the steric shapes of nonpolar alkyl groups of alkylammonium ions.

• Journal of Biosystems Engineering
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• v.32 no.5
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• pp.348-353
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• 2007

A solid state ion sensor module has been developed and evaluated for hydroponic nutrients analysis. The sensor module consisted of five ion-selective electrodes (ISE) fabricated by screen-printing technology. The electrochemical responses of ion sensors for nitrate, ammonium, potassium, calcium, and pH were measured with specially designed 7-channel low voltage signal transducers. The analytical characteristics of the sensors were comparable with those of conventional ISE sensors. The solid state ion sensors exhibit linear relationships over five concentration decades. Detection limit of the sensors were $5.6{\times}10^{-5}{\sim}1.6{\times}10^{-7}M$ depends on ions. Performance test results showed that relative errors of measured ion concentrations were less than 5% for $NO_3{^-},\;K^+,\;Ca^{2+}$ ion, and pH. The concentration of $NO_3{^-},\;NH_4{^+},\;K^+,\;Ca^{2+}$, and pH ion in standard solution and nutrient solutions could be determined by direct potentiometric measurements without any conditioning before measurements.

• Analytical Science and Technology
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• v.8 no.4
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• pp.623-630
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• 1995

Silicone rubber-based sodium-selective membranes are developed for solid-state ion sensors. It was shown that the potetiometric performance of SR-based membranes are greatly dependent on the type of neutral carriers employed; among the three ionophores, N,N,N',N'-tetracyclohexyl-1,2-phenylenedioxydiacetamide (ETH 2120), bis[(12-crown-4)methyl]dodecylmethylmalonate (D12C4DMM) and monensin methyl ester (MME), examined, only ETH 2120 was compatible with the SR-based matrix. Addition of about 20 wt% plasticizer to the SR-based matrix provided the resulting membranes with potentiometric properties essentially equivalent to those of the corresponding PVC-based membranes. Owing to the strong adhesive strength of SR-based membranes, the CWEs coated \vith those membranes exhibited long lifetime with conventional electrode-like performance. Blending of PU into the SR matrix increased the lifetime of CWEs from two weeks to one month.

• Bulletin of the Korean Chemical Society
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• v.27 no.10
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• pp.1593-1596
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• 2006

The polymeric membrane electrodes based on N,N'-bis-pyridin-2-ylmethylene-naphthalene-1,8-diamine as an ion carrier were prepared and tested for the copper-ion selective electrode. The membrane has a linear dynamic range between $10^{-6}$ and $10^{-2}$ M with a Nernstian slope of 29.6 mV per decade, and its detection limit was $10^{-5.62}$M. The potentiometric response is independent of the pH range of 3-5. The proposed electrode showed good selectivity and response for $Cu^{2+}$ over a wide variety of other metal ions in pH 4.0 buffer solutions.

• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.401-405
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• 2010

The Schiff base 1,2-bis(E-2-hydroxy benzylidene amino)anthracene-9,10-dione has been synthesized and explored as ionophore for preparing PVC-based membrane sensors selective to the copper ($Cu^{2+}$) ion. Potentiometric investigations indicate high affinity of these receptors for copper ion. The best performance was shown by the membrane of composition (w/w) of ionophore: 1 mg, PVC: 33 mg, DOP: 66 mg and KTpClPB as additive were added 50 mol % relative to the ionophore in 1 ml THF. The proposed sensor's detection limit is $2.8{\times}10^{-7}$ M over pH 5 at room temperature (Nernstian slope 31.76 mV/dec.) with a response time of 15 seconds and showed good selectivity to copper ion over a number of interfering cations.

• Analytical Science and Technology
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• v.10 no.3
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• pp.161-167
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• 1997

This is on hydrogen ion-selective memebrane electrodes which were made of tetrabenzylmethylenediamine (TBMDA), tetrabenzylethylenediamine (TBEDA), tetrabenzylpropylenediamine(TBPDA) and tetrabenzylhexylenediamine(TBHDA) as neutral carriers. Their response potentials to carbon number between amino groups showed linear selectivities to hydrogen ion in the range of pH 1~pH 9, pH 2~pH 9, pH 3~pH 9 and pH 4~pH 9 and slopes were 48mV/pH, 52mV/pH, 64mV/pH, 59mV/pH respectively. The interferences effect on the cations were measured to alkali metal ions($Li^+$, $Na^+$, $K^+$), alkaline earth metal ions ($Mg^{2+}$, $Ca^{2+}$, $Sr^{2+}$, $Ba^{2+}$), transition metals ions($Cu^{2+}$, $Ni^{2+}$, $Co^{2+}$) and anions($I^-$, $Br^-$, ${NO_3}^-$, $SCN^-$), and selectivity coefficients were measured by separate-solution method. The membrane electrode made of TBMDA among the electrodes showed the best selectivity in acidic solution.

• Bulletin of the Korean Chemical Society
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• v.28 no.4
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• pp.538-542
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• 2007

Polymeric electrodes for lead ion based on N,N'-bis-thiophen-2-ylmethylene-pyridine-2,6-diamine as an ion carrier were prepared. The membrane electrode (m-3) containing o-NPOE as a plasticizer and 50 mol% additive of ionophore gives an excellent Nernstian response (29.59 mV/decade) and the limit of detection of ?log a (M) = 5.74 to Pb2+ in Pb(NO3)2 solution at room temperature. The prepared electrode provided good sensitivity and outstanding selectivity and response for Pb2+ over a wide variety of other metal ions in pH 7.0 buffer solutions. The good sensitivity and selectivity towards lead ion are attributed to the strong complexation of lead ion to N,N'-bis-thiophen-2-ylmethylene-pyridine-2,6-diamine which has geometrically the proper cavity to coordinate to the ligand.

• Bulletin of the Korean Chemical Society
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• v.25 no.10
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• pp.1465-1470
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• 2004

A short and efficient synthesis, solvent extraction and potentiometric measurements of new thiazole-containing naphtho-crown ethers are reported. The naphthalene moiety enhances the ammonium ion selectivity over potassium ion. The selectivity of ${NH_4}^+/K^+$ follows the trend $3\;{\approx}\;2\;>\;1$, indicating that the differences in conformational changes of 2 and 3 in forming ammonium complexes affect little on the resulting ammonium/potassium extraction selectivity ratio. The ammonium ion-selective electrodes were prepared with noctylphenyl ether plasticized poly(vinyl chloride) membranes containing 1-4 the effect of one naphthalene unit introduced on either right (2) or left (3) side of thiazolo-crown ether on their potentiometric properties (e.g., ammonium ion selectivity over other cations, response slopes, and detection limits) were not apparent. However, the ammonium ion selectivity of 1, 2 and 3 over other alkali metal and alkaline earth metal cations is 10-100 times higher than that of nonactin.

• Proceedings of the PSK Conference
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• 2001.10a
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• pp.282.3-283
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• 2001

• Bulletin of the Korean Chemical Society
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• v.20 no.5
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• pp.581-586
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• 1999

A series of polyethers containing the thiazole or oxazole subcyclic moiety have been synthesized. Reaction of 2-aryl-4-hydroxymethylthiazole with tetra- and pentaethylene glycol di-p-tosylate in THF provided corresponding α,ω-bis[2'-aryl-4'-methylthiazole]polyethylene glycol in good yields. Similar treatment of 2-phenyl-4-hydroxymethyloxazole 7 and 2-phenyl-5-hydroxymethyloxazole 8 with tetraethylene glycol di-p-tosylate yielded the corresponding 1,13-bis [2'-phenyl-4'-methyloxazole]tetraethylene glycol 16 and 1,13-bis[2'-phenyl-5'-methyloxazole]tetraethylene glycol 17 in 69 and 43% yields in respectively. The potentiometric properties of PVC-based ion selective membranes containing 66 wt% o-nitrophenyloctyl ether (NPOE) and 4 wt% polyethers 9-17 have been examined. The membranes containing thiazole and oxazole polyether derivatives exhibited high selectivity toward silver (I) ion. It was observed that the response slopes of the electrodes to silver ion vary with the length of polyether chain linking two thiazole subcyclic moiety. Potentiometric data suggest that the number of ether units, CH2OCH2, for phenylthiazole derivatives be greater than 5 to result in near-Nernstian response. However, the response behaviors of the membrane electrodes based on phenyloxazole podands 16 and 17, which have different orientation, were correspondingly similar to those of the electrodes based on phenylthiazole podands 9 and 10. On the other hand, the ISEs based on thiazole polyether derivatives with different terminal substituents, e.g., phenyl 10, naphtyl 14, and thienyl 15, except that with pyridyl 12, exhibited little difference in their potentiometric properties.