• Journal of the Korean Chemical Society
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• v.33 no.3
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• pp.304-308
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• 1989

The spectrophotometric determination of $Lu^{3+},\;Eu^{3+}$ and some other rare earths have been investigated using Methyl Thymol Blue(MTB) as spectrophotometric reagent. Rare earth elements form a stable complex with MTB abount pH 6.5 and the ratio of its complex is 1 to 1. MTB has a absorption maxima at 440nm and rare earth MTB complex has absorption maxima 610nm at pH 6.5, respectively. The absorbance of the rare earth MTB complex is stable in 7 hours after color developing and obey the Beer law in the range of $0{\sim}110{\mu}g/50ml$. The ligand such as phosphate, citrate and EDTA decrease the absorbance of its complex considerably, and this method has a poor selectivity of each rare earth element and the molar absorptivity is $1.2{\sim}2.0{\times}10^4mol^{-1}{\cdot}l{\cdot}cm^{-1}$. In methyl alcohol, ethyl alcohol and acetone medium we did not find out any absorption change of the rare earth MTB complex.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3284-3288
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• 2013

This paper describes first development and validation of pentafluorophenylprophyl ligand-based liquid chromatography coupled to tandem mass spectrometry (PFPLC-MS/MS) method to determine metformin, a highly polar compound, in human plasma. Metformin and Phenformin (internal standard) were extracted from human plasma 50 ${\mu}L$ with a single-step protein precipitation. The chromatographic separation was performed using a linear gradient elution of mobile phase involving 5.0 mM ammonium formate solution with 0.1% formic acid (A) and acetonitrile (B) over 3.0 min of run time on a Phenomenex Luna PFP column. The detection was performed using a triple-quadrupole tandem mass spectrometer (Waters Quattro micro) with electrospray ionization in the mode of positive ionization and multiple-reaction monitoring (MRM). The developed method was validated with 5.0 ng/mL of lower limit of quantification (LLOQ). The calibration curve was linear over 5-3000 ng/mL of the concentration range ($R^2$ > 0.99). The specificity, selectivity, carry-over effect, precision, accuracy and stability of the method met the acceptance criteria. The method developed in this study had had rapidness, simplicity and ruggedness. The reliable method was successfully applied to high throughput analysis of real samples for a practical purpose of a pharmacokinetic study.

• Analytical Science and Technology
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• v.17 no.2
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• pp.91-97
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• 2004

Cryptand ion exchange resins were synthesized with 1-aza-15-crown-5 macrocyclic ligand attached to styrene divinylbenzene (DVB) copolymer with crosslink of 1%, 2%, 5% and 10% by substitution reaction. The synthesis of these resins was confirmed by content of chlorine, element analysis, and IR-spectrum. The effects of pH, time, dielectric constant of solvent and crosslink on adsorption of uranium ($UO{_2}^{2+}$) ion were investigated. The uranium ion was showed fast adsorption on the resins above pH 3. The optimum equilibrium time for adsorption of metallic ions was about two hours. The adsorption selectivity determined in ethanol was in increasing order uranium ($UO{_2}^{2+}$), magnesium ($Mg^{2+}$), neodymium ($Nd^{3+}$) ion. The adsorption was in order of 1%, 2%, 5%, and 10% crosslink resin and adsorption of resin decreased in proportion to order of dielectric constant of solvents.

• Applied Chemistry for Engineering
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• v.19 no.3
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• pp.304-309
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• 2008

Cryptand series ion exchange resins were synthesized with 1-aza-12-crown-4 macrocyclic ligand attached to styrene (4 series dangerous matter) divinylbenzene (DVB) copolymer with crosslink of 1％, 2％, 4％ and 8％ by a substitution reaction. The synthesis of these resins was confirmed by content of chlorine, element analysis, electron micrograph, and IR-spectrum. The effects of pH, time, dielectric constant of solvent and crosslink on adsorption of uranium (${UO_2}^{2+}$) ion were investigated. The uranium ion showed a fast adsorption on the resins above pH 3. The optimum equilibrium time for adsorption of metallic ions was about two hours. The adsorption selectivity determined in ethanol was in increasing order uranium (${UO_2}^{2+}$) > nickel ($Ni^{2+}$) > gadolinium ($Gd^{3+}$) ion. The adsorption was in order of 1％, 2％, 4％, and 8％ crosslinked resin and adsorption of resin decreased in proportion to order of dielectric constant of solvents.

• Applied Chemistry for Engineering
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• v.22 no.6
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• pp.697-702
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• 2011

Ion exchange resins have been synthesized from chloromethylated styrene-1,4-divinylbenzene (DVB) with 1%, 2%, 5% and 15%-crosslinkage and macrocyclic ligand of $OenNdien-H_4$ by copolymerization. The adsorption characteristics of uranium (${UO_2}^{2+}$), potassium ($K^+$) and neodymium ($Nd^{3+}$) metallic ions have been investigated. The synthesis of these resins was confirmed by content of chlorine, element analysis, and IR-spectrum. The effects of pH, time, and crosslinkage on adsorption of metallic ions were also studied. The uranium ion showed the fast adsorption on the resins above pH 3. The optimum equilibrium time for the adsorption of metallic ions was about two hours. The adsorption selectivity determined in methanol solution was in increasing order uranium (${UO_2}^{2+}$) > potassium ($K^+$) > neodymium ($Nd^{3+}$) ion. Moreover, the adsorption was increased with the crosslinkage concentration in order of 1%, 2%, 5% and 15%-crosslinkage resin.

• Journal of Powder Materials
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• v.30 no.1
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• pp.53-64
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• 2023

Atomic layer etching (ALE) is a promising technique with atomic-level thickness controllability and high selectivity based on self-limiting surface reactions. ALE is performed by sequential exposure of the film surface to reactants, which results in surface modification and release of volatile species. Among the various ALE methods, thermal ALE involves a thermally activated reaction by employing gas species to release the modified surface without using energetic species, such as accelerated ions and neutral beams. In this study, the basic principle and surface reaction mechanisms of thermal ALE?processes, including "fluorination-ligand exchange reaction", "conversion-etch reaction", "conversion-fluorination reaction", "oxidation-fluorination reaction", "oxidation-ligand exchange reaction", and "oxidation-conversion-fluorination reaction" are described. In addition, the reported thermal ALE processes for the removal of various oxides, metals, and nitrides are presented.

• Analytical Science and Technology
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• v.22 no.1
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• pp.92-100
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• 2009

Azacrown resins were synthesized by mixing 1-aza-12-crown-4 macrocyclic ligand into styrene (2th petroleum in 4th class hazardous materials) divinylbenzene (DVB) copolymer with crosslinkage of 1%, 2%, 5% and 10% by substitution reaction. The synthesis of these resins was confirmed by content of chlorine, element analysis, thermogravimetric analysis (TGA), surface area (BET), and IR-spectroscopy. The effects of pH, time, crosslinkage of resins and dielectric constant of solvent on adsorption of metal ions by resin adsorbent were investigated. Metal ions showed a great adsorption over pH 3 and adsorption equilibrium of metal ions was about two hours. In addition, adsorptive selectivity of metals on the resin in ethanol solvent was increased in the order of ${UO_2}^{2+}$ > $Ca^{2+}$ > $Sm^{3+}$ ion and adsorption of uranium ion was decreased with increase of crosslinkage such as 1%, 2%, 5% and 10% and was inversely proportional to the order of dielectric constant of solvents.

• Analytical Science and Technology
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• v.21 no.2
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• pp.109-116
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• 2008

Resins were synthesized by mixing 1-aza-18-crown-6 macrocyclic ligand into styrene(dangerous matter) divinylbenzene(DVB) copolymer with crosslink of 1%, 2%, 6% and 12% by substitution reaction. The synthesis of these resins was confirmed by content of chlorine, elemental analysis, thermogravimetric analysis, electron microscopy, and IR. The effects of pH, time, crosslink of resins and dielectric constant of solvent on adsorption of uranium ion by resin adsorbent were investigated. Uranium ion showed a great adsorption above pH 3 and adsorption equilibrium of metal ions was established in about two hours. In addition, adsorptive selectivity of resin in ethanol solvent was $UO{_2}^{2+}$ > $Zn^{2+}$ > $Lu^{3+}$ ion and adsorption of uranium ion increased with the increase of the degree of crosslinking (1%~12%) and was inversely in proportional to the order of dielectric constant of solvents.

• Biomolecules & Therapeutics
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• v.29 no.4
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• pp.392-398
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• 2021

In this study, we determined the effect of 24 different synthetic 4-benzylpiperidine carboxamides on the reuptake of serotonin, norepinephrine, and dopamine (DA), and characterized their structure-activity relationship. The compounds with a two-carbon linker inhibited DA reuptake with much higher potency than those with a three-carbon linker. Among the aromatic ring substituents, biphenyl and diphenyl groups played a critical role in determining the selectivity of the 4-benzylpiperidine carboxamides toward the serotonin transporter (SERT) and dopamine transporter (DAT), respectively. Compounds with a 2-naphthyl ring were found to exhibit a higher degree of inhibition on the norepinephrine transporter (NET) and SERT than those with a 1-naphthyl ring. A docking simulation using a triple reuptake inhibitor 8k and a serotonin/norepinephrine reuptake inhibitor 7j showed that the regions spanning transmembrane domain (TM)1, TM3, and TM6 form the ligand binding pocket. The compound 8k bound tightly to the binding pocket of all three monoamine reuptake transporters; however, 7j showed poor docking with DAT. Co-expression of DAT with the dopamine D₂ receptor (D₂R) significantly inhibited DA-induced endocytosis of D₂R probably by reuptaking DA into the cells. Pretreatment of the cells with 8f, which is one of the compounds with good inhibitory activity on DAT, blocked DAT-induced inhibition of D₂R endocytosis. In summary, this study identified critical structural features contributing to the selectivity of a molecule for each of the monoamine transporters, critical residues on the compounds that bound to the transporters, and the functional role of a DA reuptake inhibitor in regulating D₂R function.

• Analytical Science and Technology
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• v.9 no.3
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• pp.270-278
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• 1996

Response mechanism for the chloride-selective membrane doped with 5, 10, 15, 20-tetraphenyl(porphyrinato)manganase(III) chloride(Mn(TPP)Cl) in PVC/DOS matrix is proposed by examining the visible spectra of the corresponding optode membrane. The visible spectra of Mn(TPP)Cl-doped membrane placed in aqueous solution show that the chloride ligand is easily replaced with water molecule. When other halogen ions, such as $F^-$, $Br^-$ and $I^-$, are added to the sample solution, they replace the water ligand, exhibiting distinctive change in the Soret band of Mn(TPP). On the other hand, bulky anions, such as SCN and salicylate, do not form a bond with the central metal. These results suggests that the potentiometric response of Mn(TPP)-based membrane results either from the ligand exchange (water with halides) at the central metal or from the counter ion exchange (chlorides with bulky lipophilic anions) around the positively charged porphyrin molecule in membrane phase. It was also noted that both hydration enthalpies of anions and their binding constants to Mn(TPP) play critical role in determining the potentiometric selectivity pattern of the membrane.