• Analytical Science and Technology
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• v.9 no.1
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• pp.78-83
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• 1996

Hydrogen ion-selective membrane electrodes based on tribenzylamine(TBA), tetrabenzylethylenediamine(TBEDA), pentabenzyldiethylenetriamine(PBDETA) as neutral carriers were shown good selectivity and linearity in the range of pH 1~pH 9, pH 2~pH 12, pH 4~pH 12. The pH selectivity of this membrane electrodes have nothing relation with the numbers of unshared electron pair in TBA, TBEDA, PBDETA and were shown a slope of 43.8mV/pH, 46.9mV/pH, 43.6mV/pH respectively. The selectivity coefficients were determined by the separate solution method for alkali($Li^+$, $Na^+$, $K^+$), alkaline earth metal($Ba^{2+}$, $Ca^{2+}$, $Mg^{2+}$) and transition metal ions($Mn^{2+}$, $Co^{2+}$, $Ni^{2+}$, $Cu^{2+}$, $Zn^{2+}$). The membrane electrode based on TBEDA appeared the best results as hydrogen ion electrode.

• Clean Technology
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• v.11 no.2
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• pp.69-74
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• 2005

A metal ion detector with a submicron size electrode was fabricated by field-induced AFM oxidation. The square frame of the mesa pattern was functionalized by APTES for the metal ion detection, and the remaining portion was used as an electrode by the self-assembly of MPTMS for Au metal deposition. The conductance changed with the quantity of adsorbed copper ions, due to electron tunneling between the mobile and surface electrodes. The smaller electrode has a lower limit of detection due to the enhancement in electron tunneling through metal ions that are adsorbed between the conductive-tip (mobile) and the surface (fixed) electrode. This two-electrode system immobilized with different functional groups was successfully used in the selective adsorption and detection of target materials.

• Journal of the Korean Chemical Society
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• v.48 no.3
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• pp.266-272
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• 2004

We developed a miniaturized solid-state carbonate ion-selective electrode (carbonate ISE) based on one-component room temperature vulcanizing type silicone rubber 730 (730 RTV) without adding plasticizer to the matrix. The optimized carbonate ion selective membrane is prepared with 85.8 wt% of 730 RTV, 11.1 wt% of trifluoroacetyl-p-decylbenzene (TFADB), and 3.1 wt% of tridodecyl-methylammonium chloride (TDMACl). This carbonate ISE exhibited excellent potentiometric properties (i.e., slope: 26.3 mV/dec; selectivity: $logKT^{pot}_{CO_{2},Cl^-}$= -4.00 and $logKT^{pot}_{TCO_{2},Sal^-}$=1.69); and detection limit for $TCO_2:\;4.0{\times}10^{-4}M$). In addition, the early potentiometric properties of the solid-state sensor with optimized membrane composition were not deteriorated for more than 60 days.

• Bulletin of the Korean Chemical Society
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• v.27 no.9
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• pp.1439-1444
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• 2006

A $Cu^{2+}$ ion-selective membrane microelectrode has been fabricated from poly vinyl chloride (PVC) matrix membrane containing a new symmetrical hexadentate Schiff,s base 2-{1-(E)-2-((Z)-2-{(E)-2-[(Z)-1-(2-hydroxyphenyl)ethylidene]hydrazono}-1-methylpropylidene)hydrazono]ethyl}phenol (HDNOS) as a neutral carrier, Potassium tetrakis(4-chlorophenyl) borate (KTpClPB) as an anionic excluder and o-nitrophenyloctyl ether (NPOE) as a plasticizing solvent mediator. The microelectrode displays linear potential response in the concentration range of $1.0\;{\times}\;10^{-5}-1.0\;{\times}\;10^{-11}$ M of $Cu^{2+}$. The microelectrode exhibits a nice Nernstian slope of 25.9 ${\pm}$ 0.3 mV $decade^{-1}$ in the pH range of 3.1-8.1. The sensor has a relatively short response time in whole concentration ranges ($\sim$5 s). The detection limit of proposed sensor is $5.0\;{\times}\;10^{-12}$ M (320 pg/L), and it can be used over a period of eight weeks. The practical utility of the sensor has been demonstrated by using it as an indicator electrode in the potentiometric titration of $Cu^{2+}$ with EDTA. The proposed membrane electrode was used for the direct determining of $Cu^{2+}$ content in black and red pepper, and in waste water samples.

• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.870-877
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• 1998

With impedance spectrum measurements, impedance was studied in the interface between sample solutions for $K^+-ion$ selective PVC membrane electrode containing neutral carriers [dibenzo-18-crown-6 (D18Cr6) and valinomycine (Val)]. Response characteristics of electrode were examined by measuring AC impedance spectra that were resulted from the chemical structure and the content of carrier, variation of plasticizer, membrane thickness, doping of base electrolytes, and concentration variation of sample solution. Transport characteristics of PVC membrane electrode were also studied. It was found that the equivalent circuit for the membrane in $K^+$ solution could be expressed by a series combination of solution resistance and a parallel circuit consisting of the bulk resistance and geometric capacitance of the membrane system. But the charge transfer resistance and Warburg resistance were overlapped a little in the low concentration and low frequency ranges. The carrier, D18Cr6 was best for electrode and impedance characteristics, and ideal electrode characteristics were appeared especially in case of doping of the base electrolyte[potassium tetraphenylborate(TPB)]. The optimum carrier content was about 3.23 wt% in case of D18Cr6 and Val. DBP was best as a plasticizer. As membrane thickness decreased the impedance characteristics was improved, but electrode characteristics were lowered for membrane thickness below the optimum. In the case of D18Cr6, the selectivity coefficients by the mixed solution method for the $K^+$ ion were the order of $NH_4{^+}>Ca^{2+}>Mg^{2+}>Na^+$.

• Bulletin of the Korean Chemical Society
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• v.27 no.10
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• pp.1581-1586
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• 2006

A La (III) ion-selective membrane sensor has been fabricated from poly vinyl chloride (PVC) matrix membrane, containing 3-hydroxy-N'-(pyridin-2-ylmethylene)-2-naphthohydrazide (HPMN) as a neutral carrier, potassium tetrakis (p-chlorophenyl) borate (KTpClPB) as an anionic excluder and ortho-nitrophenyloctyl ether (NPOE) as a plasticizing solvent mediator. The effects of membrane composition and pH as well as the influence of the anionic additive on the response properties were investigated. The sensor with 30% PVC, 62% solvent mediator, 6% ionophore and 2% anionic additive, shows the best potentiometric response characteristics. It displays a Nernstian behavior (19.2 mV per decade) across the range of $1.0{\times}10^{-2}-1.0{\times}10^{-7}$ M. The detection limit of the electrode is $7.0{\times}10^{-8}$ M ($\sim$10 ng/mL) and the response time is 15 s from $1.0{\times}10^{-2}$ up to $1.0{\times}10^{-4} $M and 30 s in the range of $1.0 {\times}10^{-5}-1.0{\times}10^{-7}$ M. The sensor can be used in the pH values of 3.0-9.0 for about seven weeks. The membrane sensor was used as an indicator electrode in the potentiometric titration of lanthanum ions with EDTA. It was successfully applied to the lanthanum determination in some mouth wash preparations.

• Journal of the Korean Chemical Society
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• v.36 no.5
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• pp.638-643
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• 1992

The analytical response properties of two types of continuous flow-through electrode system as fulfide ion detectors are examined and directly compared their reponse characteristics under the optimal conditions. In both detection systems, observed peak potentials are logarithmically related to the sulfide ion concentration and at least twenty samples per hour can be determined. In the pH electrode method, the pH of the flowing recipient stream leaving the dialyzer was monitored. The designed system involves the use of continuous flow gas dialyzer in conjunction with the tubular polymer membrane electrode. In this method, optimal experimental conditions are recipient of mixture of $5.0 {\times} 10^{-5} M NaOH ＋ 5.0 {\times} 10^{-3} M$ NaCl and diluent of 0.10 M $H_2SO_4$, and all flow rates of recipient stream, diluent stream, and sample are 1.0 ml/min. In the sulfide ion electrode method, a commercially available sulfide ion-selective electrode was used to detect sulfide ion in the flow-through cell. The optimal flow rates of sulfide anti-oxidant buffer (3.5 g ascorbic acid and 7.6 g $Na_2EDTA$ dissolved in 1.0 M NaOH solution 1 l) and sample were 1.4 ml/min and 1.0 ml/min, respectively.

• Bulletin of the Korean Chemical Society
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• v.23 no.2
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• pp.346-350
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• 2002

A glassy carbon electrode (GCE) modified with 2,2':6':2”-terpyridine (2,2':6':2”-TPR) using a spin coating method was applied for the highly selective and sensitive analysis of a trace amount of $Hg_2^{2+}$ ions. Various experimental parameters, which influenced the response of the 2,2':6':2”-TPR modified electrode to $Hg_2^{2+}$ ions, were optimized. The linear sweep and differential pulse voltammograms for the 2,2':6':2”-TPR modified electrode deposited with Hg show a well-defined anodic peak at +0.65 V (vs. Ag|AgCl). After a 25 min preconcentration time in an $Hg_2^{2+}$ ion solution (0.1 M acetate buffer, pH 5.0), differential pulse voltammetry(DPV) with 2,2':6':2”-TPR modified electrode shows a linear response between $1.0\;{\times}\;10^{-6}M\;and\;2.0\;{\times}\;10^{-7}M$. The least-square treatment of these data produce an equation of I[${\mu}A$] = 0.031 + 0.005C with r = 0.980(n = 5). The detection limit of this electrode with linear sweep voltammetry and differential pulse anodic voltammetry were $2.0\;{\times}\;10^{-6}M\;and\;8.0\;{\times}\;10^{-8}M$, respectively. The presence of Pb, Fe, Cd, Ti, Ni, Co, Mg, Al, Mn, and Zn did not interfere in the analysis of the $Hg_2^{2+}$ ion. The 2,2':6':2”-TPR modified GCE has been successfully applied in determination trace amounts of Hg in a human urine sample.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.203-203
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• 2012

The SWCNTs network are formed on various plastic substrates such as poly(ethylene terephthalate) (PET), polyimide (PI) and soda lime glass using roll-to-roll printing and spray process. Selective patterning of carbon nanotubes film on transparent substrates was performed using a femtosecond laser. This process has many advantages because it is performed without chemicals and is easily applied to large-area patterning. It could also control the transparency and conductivity of CNT film by selective removal of CNTs. Furthermore, selective cutting of carbon nanotube using a femtosecond laser does not cause any phase change in the CNTs, as usually shown in focused ion beam irradiation of the CNTs. The patterned SWCNT films on transparent substrate can be used electrode layer for touch panels of flexible or flat panel display instead indium tin oxide (ITO) film.

• Journal of Electrochemical Science and Technology
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• v.2 no.3
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• pp.143-145
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• 2011

Metal-binding antibiotics are very attractive choices as cation selective ionophores. The ability of tetracycline (TC) antibiotics to bind to metal ions has obtained much attention. TCs exhibit the potentiometric performance changes for various cations dependant on several experiment conditions. In this report, we investigated the potentiometric performance changes of TC as the modification of TC's possible metal binding site. We found that the selectivity alter with the blocking main binding site of ionophores for cations. And, additionally it is possible to control the selectivity of sensors with chemical modification of ionophores.