• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.800-804
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• 2011

A potentiometric sensor based on the Schiff base $(N^2E,N^{2'}E)-N^2,N^{2'}$-bis(thiophen-2-ylmethylene)-1,1'-binaphthl-2,2'-diamine has been synthesized and explored as an ionophore PVC-based membrane sensor selective for the silver ($Ag^+$) ion. Potentiometric investigations indicate a high affinity of this receptor for the silver ion. Seven membranes have been fabricated with different compositions, with the best performance shown by the membrane with an ionophore composition (w/w) of: 1.0 mg, PVC: 33.0 mg, DOA: 66.0 mg in 1.0 mL THF. The sensor worked well within a wide concentration range of $1.0{\times}10^{-2}$ to $1.0{\times}10^{-7}$ M, at pH 5, at room temperature (slope 57.4 mV/dec.), and with a rapid response time of 9 s; the sensor also showed good selectivity towards the silver ion over a huge number of interfering cations, with the highest selectivity coefficient for $Hg^{2+}$ at -3.7. Thus far, the best lower detection limit was $4.0{\times}10^{-8}$ M.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1562-1564
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• 2014

• Bulletin of the Korean Chemical Society
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• v.25 no.2
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• pp.177-181
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• 2004

A PVC membrane electrode for silver ion based on a new cone shaped calix[4]arene (CASCA) as membrane carrier was prepared. The electrode exhibits a Nernstian response for $Ag^+$ over a wide concentration range ($1.0{\times}10^{-1}-8.0{\times}10^{-6}$M) with a slope of 58.2 {\pm}$ 0.5 mV per decade. The limit of detection of the sensor is $5.0{\times}10^{-6}$M. The sensor has a very fast response time (~5 s) in the concentration range of ${\leq}=1.0{\times}10^{-3}$ M, and a useful working pH range of 4.0-9.5. The proposed sensor displays excellent discriminating ability toward $Ag^+$ ion with respect to common alkali, alkaline earth, transition and heavy metal ions. It was used as an indicator electrode in potentiometric titration of $Ag^+$ with EDTA and in direct determination of silver ion in wastewater of silver electroplating.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1699-1703
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• 2010

The Schiff base N,N'-bis(pyridin-2-ylmethylene)benzene-1,2-diamine [BPBD] has been synthesized and explored as ionophore for preparing PVC-based membrane sensors selective to the silver ($Ag^+$) ion. Potentiometric investigations indicate high affinity of this receptor for silver ion. The best performance was shown by the membrane of composition (w/w) of ionophore: 1 mg, PVC: 33 mg, o-NPOE: 66 mg and additive were added 50 mol % relative to the ionophore in 1 mL THF. The sensor works well over a wide concentration range $1{\times}10^{-3}$ to $1.0{\times}10^{-7}$ M by pH 6 at room temperature (slope 58.6 mV/dec.) with a response time of 10 seconds and showed good selectivity to silver ion over a number of cations. It could be used successfully for the determination of silver ion content in environmental and waste water samples.

• Bulletin of the Korean Chemical Society
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• v.24 no.1
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• pp.23-26
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• 2003

Titanium acetylacetonate was used in the construction of a PVC-based membrane electrode. This sensor shows very good selectivity for iodide ion over a wide variety of common inorganic and organic anions. It exhibits Nernstian behavior with a slope of 59.1 mV per decade. The working concentration ranges of the sensor are with a detection limit of $3.0\;{\times}\;10^{-6}\;M$. The response time of the sensor is very fast (<8 s), and can be used for at least twelve weeks in the pH range of 4.0-9.2. The best performance was obtained with a membrane composition of 30% PVC, 65% dibutylphthalate, 3% titanium acetylacetonate and 2% hexadecyltrimethylammonium bromide. The proposed sensor was successfully applied as an indicator electrode for titration of iodide with silver ion.

• Applied Chemistry for Engineering
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• v.32 no.4
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• pp.456-460
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• 2021

A potentiometric sodium-ion (Na⁺) sensor was prepared using a screen-printing process with carbon and silver inks. The two-electrode configuration of the sensor resulted in potential differences in Na⁺ solutions according to Nernstian equation. The obtained Na⁺-sensor exhibited an ideal Nernstian sensitivity, fast response time, and low limit of detection. The Nernstian response was stable when the sensor was tested for repeatability and long-term durability. The Na⁺-selective membrane coated onto the carbon electrode selectively passed sodium ions against interfering ions, indicating an excellent selectivity. The portable Na⁺-sensor was finally fabricated using a printed circuit system, demonstrating the successful measurements of Na⁺ concentrations in various real samples.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.101-101
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• 2018

Quantitative measurement of chloride ion concentration has an important role in various fields of electrochemistry, medical science, biology, metallurgy, architecture, etc. Among them, its importance of architecture is ever-growing due to unexpected degradations of building structure. These situations are caused by corrosion of reinforced concrete (RC) structure of buildings. And chloride ions are the most powerful factors of RC structure corrosion. Therefore, precise inspection of chloride ion concentration must be required to increase the accuracy of durability monitoring. Multi-walled Carbon nanotubes (MWCNTs) have high chemical resistivity, large surface area and superior electrical property. Thus, it is suitable for the channels of electrical signals made by the sensor. Silver nanoparticles were added to giving the sensing property. CuBTC, one of the metal organic frameworks (MOFs), was employed as a material to improve the sensing property because of its hydrophilicity and high surface area to volume ratio. In this study, sensing element was synthesized by various chemical reaction procedures. At first, MWCNTs were functionalized with a mixture of sulfuric acid and nitric acid because of enhancement of solubility in solution and surface activation. And functionalized MWCNTs, silver nanoparticles, and CuBTC were synthesized on PTFE membrane, one by one. Electroless deposition process was performed to deposit the silver nanoparticles. CuBTC was produced by room temperature synthesis. Surface morphology and composition analysis were characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), respectively. X-ray photoelectron spectroscopy (XPS) was also performed to confirm the existence of sensing materials. The electrical properties of sensor were measured by semiconductor analyzer. The chloride ion sensing characteristics were confirmed with the variation of the resistance at 1 V.

• Bulletin of the Korean Chemical Society
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• v.23 no.1
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• pp.53-58
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• 2002

A new PVC-membrane electrode for $Ag^+$ ion based on a thia-substituted macrocyclic diamide has been prepared. The electrode exhibited a Nernstian response for $Ag^+$ over a wide concentration range $(1.7{\times}10^{-6}-1.0{\times}10^{-1}M)$. It has a response time <15 s and can be used for at least 3 months without divergence. The proposed membrane sensor revealed good selectivities for $Ag^+$ over a variety of metal ions and can be used in a pH range 3.0-7.5. It has been used successfully for direct determination of $Ag^+$ in different real samples and, as an indicator electrode, in the titration of silver ion.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.2003-2007
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• 2011

We report a highly sensitive surface-enhanced Raman scattering (SERS) platform for the selective trace analysis of mercury (II) ions in drinkable water using aptamer-conjugated silver nanoparticles. Here, an aptamer designed to specifically bind to $Hg^{2+}$ ions in aqueous solution was labelled with a TAMRA moiety at the 5' end and used as a Raman reporter. Polyamine spermine tetrahydrochloride (spermine) was used to promote surface adsorption of the aptamer probes onto the silver nanoparticles. When $Hg^{2+}$ ions are added to the system, binding of $Hg^{2+}$ with T-T pairs results in a conformational rearrangement of the aptamer to form a hairpin structure. As a result of the reduced of electrostatic repulsion between silver nanoparticles, aggregation of silver nanoparticles occurs, and the SERS signal is significantly increased upon the addition of $Hg^{2+}$ ions. Under optimized assay conditions, the concentration limit of detection was estimated to be 5 nM, and this satisfies a limit of detection below the EPA defined limit of 10 nM in drinkable water.

• Korean Chemical Engineering Research
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• v.61 no.3
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• pp.463-471
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• 2023

Nitrogen-rich carbon dots (NDots) were synthesized by using uric acid as carbon and nitrogen sources. The as-synthesized NDots showed strong dual emissions at 420 nm and 510 nm with excitation at 350 nm and 460 nm, respectively. The physicochemical analyses such as X-ray photoelectron spectroscopy, Transmission electron microscopy and Fourier transform infrared spectroscopy were used to analyze the chemical, physical and morphological structures of NDots. The as-synthesized NDots exhibited wide linear range (0-100 µM) and very low detection limit (124 nM) in Ag⁺ ion sensing. In addition, Ag⁺ saturated NDots could be used as an EDTA sensor by the EDTA induced PL recovery.