• 약학회지
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• 제44권2호
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• pp.135-140
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• 2000

Determination of Aconitum alkaloids in processed Buza (Cho-0, Salted Buza, Moist-heating Buza, Limed Buza), which had been prepared from the raw tubers of Aconitum chiisanenseb(Ranunculaceae), was established using visible spectrophotometry and high-performance liquid chromatography (HPLC) method especially for Aconitine analysis. Aconitum alkloids were reacted with tetra- thiocy-anatocobalt[II] complex ion to form a stable ion pair. The reaction product was insoluble in water but freely soluble in several organic solvents. 1.2-Dichloroethane was the best extracting solvent among the examined solvents. Spectrophotometry of Aconitum alkaloids at nax. 625 was carried out. The HPLC method for aconitine was carried out using Radial PAK-CN column with gradient solvent system by solvent mixture of acetonitrile and phosphate buffer (pH 3.0) at 4$0^{\circ}C$ and 254 nm. Linear relationship was found between absorbance response and concentration of aconitine in range of 0.45 mM~0.9 mM ($r^2$=0.9949) by spectrophotometry and 0.3 mM~1.2mM($r^2$=0.9983) by HPLC method. These methods have been found to be suitable and reproducible for routine analysis of Aconitum alkaloids and its pharmaceutical preparations.

• Bulletin of the Korean Chemical Society
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• 제19권4호
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• pp.439-444
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• 1998

The protonation of tetraphenylporphyrin (TPP) in acidic organic solutions was analyzed by acid titrimetric and temperature-dependent absorption measurements. Competition between the protonation of free base TPP $(TPPH_2)$ and the solvation of proton by near solvent molecules determines the equilibrium of the diprotonated TPP $(TPPH_4^{2+})$ formation. The diprotonated TPP exists as an ion pair complex with the acid counterions, which are found to affect the degree of red shift of the Soret band. The rotation of the phenyl rings also plays an important role in the diprotonation, as suggested by the decrease in the degree of diprotonation for the fluorophenyl TPP derivatives whose phenyl ring rotation is significantly hindered relative to normal TPP. The difference of fluorescence lifetime between $TPPH_2 \;({\pi}_{FL}=19.6\;ns)\; and\; TPPH_4^{2+} \;({\pi}_{FL}=2.1 \;ns)$ was used advantageously to measure the rate of protonation in the excited state. The protonation of TPPH2 are found to occur much slower than the diffusion of protons from bulk solution to the porphyrin ring. The monoprotonated TPP is suggested to be the transient species for the diprotonation process.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.147.2-147.2
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• 2003

A fast and matrix-assisted laser desorption/ionization-mass spectrometry compatible protein staining method in one- and two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis is described. It is based on the counterion dye staining method that employs oppositely charged two dyes, Zincon and Ethyl Violet to form an ion-pair complex. It is safe to use since the methanol used previously in staining solution was replaced with ethanol, which is not toxic. The protocol including fixing, staining and quick washing steps can be completed in 1 to 1.5 h depending upon gel thickness. (omitted)

• Bulletin of the Korean Chemical Society
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• 제31권10호
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• pp.2813-2818
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• 2010

A novel method was developed for the speciation of chromium in natural water samples based on homogeneous liquid-liquid extraction and determination by flame atomic absorption spectrometry (FAAS). In this method, Cr(III) reacts with a new Schiff's base ligand to form the hydrophobic complex, which is subsequently entrapped in the sediment phase, whereas Cr(VI) remained in aqueous phase. The Cr(VI) assay is based on its reduction to Cr(III) by the addition of sodium sulfite to the sample solution. Thus, separation of Cr(III) and Cr(VI) could be realized. Homogeneous liquid-liquid extraction based on the pH-independent phase-separation process was investigated using a ternary solvent system (water-tetrabutylammonium ion ($TBA^+$)-chloroform) for the preconcentration of chromium. The phase separation phenomenon occurred by an ion-pair formation of TBA and perchlorate ion. Then sedimented phase was separated using a $100\;{\mu}L$ micro-syringe and diluted to 1.0 mL with ethanol. The sample was introduced into the flame by conventional aspiration. After the optimization of complexation and extraction conditions such as pH = 9.5, [ligand] = $1.0{\times}10^{-4}\;M$, [$TBA^+$] = $2.0{\times}10^{-2}\;M$, [$CHCl_3$] = $100.0\;{\mu}L$ and [$ClO_4$] = $2.0{\times}10{-2}\;M$, a preconcentration factor (Va/Vs) of 100 was obtained for only 10 mL of the sample. The relative standard deviation was 2.8% (n = 10). The limit of detection was sufficiently low and lie at ppb level. The proposed method was applied for the extraction and determination of chromium in natural water samples with satisfactory results.

• Nuclear Engineering and Technology
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• 제31권2호
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• pp.182-191
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• 1999

The sorption of UO$_{2}$$^{2+}$ onto goethite and kaolinite under various experimental conditions was successfully interpreted using surface complexation modeling (SCM). The SCM approach used in this work is the triple-layer model (TLM) in which weakly bonded ions are modeled as outer-sphere (ion-pair) complexes and strongly bonded ions as inner-sphere (surface coordination) complexes. The change of ionic strength did not affect the U(VI) sorption onto goethite, thus the formation of inner-sphere surface complexes, (FeO)$_2$UO$_2$ and (FeO)$_2$(UO$_2$)$_3$OH$_{5}$ was assumed to simulate the effects of ionic strength and goethite concentration. On the other hand, the U(VI) sorption onto kaolinite showed ionic strength dependence, thus the formation of AlO-UO$_{2}$$^{2+}$(outer-sphere complex) and SiO(UO$_2$)$_3$OH$_{5}$ (inner-sphere complex) was assumed to simulate the experimental data. In the presence of carbonates, the sorption of U(VI) onto kaolinite decreased in the weakly alkaline pH range. This was well simulated assuming the formation of a outer-sphere surface complex, A1OH$^{2+}$- (UO$_2$)$_2$CO$_3$OH$_3$. Since SCM approach uses thermodynamic data such as surface complexation constants, it is more predictive than empirical modeling approach in which conditional values such as partition coefficient are used. used.

• Bulletin of the Korean Chemical Society
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• 제31권6호
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• pp.1704-1710
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• 2010

The structure of a 2D grid-like copper(II) complex [Cu$(NCO)_2$(pyz)](pyz=pyrazine) (1) consists of 1D chains of Cu-pyz units connected by double end-on (EO) cyanato bridges. Each Cu(II) ion has a distorted octahedral coordination, completed by the four EO cyanato and two pyrazine ligands. Magnetic interactions through EO cyanato and pyrazine bridges in 1 are discussed on the basis of DFT broken-symmetry calculations at the B3LYP level. For model dicopper(II) complexes I (bridged by cyanato) and II (bridged by pyrazine), electronic structure calculations reproduce very well the experimental couplings for the S = 1/2 ferromagnetic and antiferromagnetic exchange-coupled 2D system: the calculated exchange parameters J are +1.25 $cm^{-1}$ and -3.07 $cm^{-1}$ for I and II, respectively. The $\sigma$ orbital interactions between the Cu $x^2-y^2$ magnetic orbitals and the nitrogen lone-pair orbitals of pyrazine are analyzed from the viewpoint of through-bond interaction. The energy splitting of 0.106 eV between two SOMOs indicates that the superexchange interaction should be antiferromagnetic in II. On the other hand, there are no bridging orbitals that efficiently connect the two copper(II) magnetic orbitals in I because the HOMOs of the basal-apical NCO bridge do not play a role in the formation of overlap interaction pathway. The energy separation in the pair of SOMOs of I is calculated to be very small (0.054 eV). This result is consistent with the occurrence of weakly ferromagnetic properties in I.

• 분석과학
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• 제7권3호
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• pp.413-419
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• 1994

생체시료 중에 함유된 베크로늄브로마이드(VeBr)를 정량하기 위해 로즈벵갈(RB)과 이온쌍착물(ion-pair complex)을 형성시켜 유기용매층으로 이행시킨 다음 형광광도법 및 형광검출기를 이용한 고속액체크로마토그래프(HPLC)법으로 정량하였다. 이 때 이온쌍착물의 최적 추출조건을 검토하기 위하여 완충액의 pH, 추출용매, 진탕시간의 영향을 실험하였다. 한편, 이온착물의 형성 및 조성은 연속변화법, 몰비법, IR, $^1H$-NMR로 확인하였으며, 또한 베크로늄브로마이드와 동시 투여될 수 있는 약물의 영향도 검토하였다.

• 멤브레인
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• 제3권3호
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• pp.126-135
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• 1993

감응물질로 제4급 암모늄염을 사용하여 PVC를 지지체로 과염소산이온의 농도 $10^{-6}M$까지 측정가능한 이온 선택성 전극을 제작하였다. 감응물질의 화학적 구조와 함량, 가소제의 종류 및 막 두께에 따른 선형응답 범위와 Nernst의 기울기 등 전극특성을 검토하여, 최적 막조건을 구한 다음 측정가능 pH범위와 여러 방해이온에 대한 선택계수를 비교 검토하였다. 과염소산 이온선택성 전극에서 감응물질의 화학적 구조 즉, 알킬기의 탄소고리수가 증가할수록 선형응답 범위 등 전극 특성은 Aliquat 336P, TOAP, TDAP 및 TDDAP의 순서로 좋아졌다. 가소제는 DBP가 가장 좋았고, 감응물질의 양은 최적 함량 이상에서 적을수록 좋았다. 최적 막 조성은 TDDAP 9.09, PVC 30.3 및 DBP 60.61wt%이었고, 막두께 0.45mm이었다. 이 조건에서 선형응답 범위 $10^{-1}~1.2 {\times} 10^{-6}M$, 검출한계 $5.1{\times}10^{-7}M$ 및 Nernst기울기 $57mV/pClO_4$이었다. 막전위는 pH 4~11 범위에서 pH의 영향을 받지 않았으며, 선택계수 서열은 다음과 같았다. $SCN^->I^->NO_3^->Br^->ClO_3^->F^->Cl^->SO_4^{2-}$

• Bulletin of the Korean Chemical Society
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• 제25권3호
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• pp.365-372
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• 2004

Two simple, rapid and sensitive spectrophotometric methods for the determination of three fluoroquinolones, namely levofloxacin, norfloxacin and ciprofloxacin have been performed either in pure form or in their tablets. In the first method, levofloxacin and norfloxacin are directly treated with bromocresol green (BCG) in dichloromethane while ciprofloxacin is allowed to react with the same dye in aqueous acidic buffer. Highly yellow colored complex species were formed instantaneously in case of levofloxacin and norfloxacin or after extraction into dichloromethane for ciprofloxacin. The formed complexes are quantified spectrophotometrically at their absorption maxima at 411 nm for levofloxacin and 412 nm for norfloxacin and ciprofloxacin. The second method involves the reaction of levofloxacin with ${\rho}$-chloranilic acid ( ${\rho}$-CA) and norfloxacin with tetracyanoethylene (TCNE) in acetonitrile to give complexes with maximum absorbance at 521 and 333 nm for the two drugs, respectively. Adopting the first procedure, calibration graphs were linear over the range 1- 20 ${\mu}g\;mL^{-1}$ with mean percentage recoveries of 100.41 ${\pm}$ 0.72, 99.99 ${\pm}$ 0.54 and 100.23 ${\pm}$ 0.91 for the theree drugs, respectively. For the second procedure, the concentration ranges were 15-250 ${\mu}g\;mL^{-1}$ for levofloxacin using ${\rho}$-CA and 0.8-16 ${\mu}g\;mL^{-1}$ for norfloxacin using TCNE with mean percentage recoveries of 99.88 ${\pm}$ 0.45 and 100.26 ${\pm}$ 0.68 for the two drugs, respectively. The proposed methods were successfully applied to determine these drugs in their tablet formulations and the results compared favorably to that of reference methods. The proposed methods are recommended for quality control and routine analysis.

• 대한화학회지
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• 제29권3호
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• pp.239-246
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• 1985

[Cu(dl-trans-[14]-diene)]$^{2+}$ 착이온과 음이온(L$^{n-}$ = S$_2$O$_3^{2-}$, SCN$^-$, I$^-$, NO$_2^-$)사이의 화학평형 관계를 온도 15 ~ 35$^{\circ}C$, 압력 1 ~ 1500bar 범위에서 분광광도법으로 연구하였다. S$_2$O$_3^{2-}$, SCN$^-$, I$^-$ 및 NO$_2^-$일때 평형상수 K는 25$^{\circ}C$, 1500bar에서 각각 3.0, 1.9, 0.6 및 0.5이었다. K값은 온도와 압력이 증가함에 따라 감소하였다. K에 대한 온도 영향으로 부터 열역학적 파라메터(${\Delta}G^{\circ}$, ${\Delta}H^{\circ}$, ${\Delta}S^{\circ}$)를 계산하였으며, 이 결과 NO$_2^-$이온을 제외한 다른 이온(S$_2$O$_3^{2-}$, SCN$^-$, I$^-$)에서는 모두 발열반응으로 나타났다. K에 대한 압력 영향에서 얻은 반응체적변화(${\Delta}$V)는 각 음이온에서 모두 양의 값이었다. S$_2$O$_3^{2-}$ 이온일 때 1,500, 1,000 및 1,500bar에서의 ${\Delta}$V(cm$^3$/mole)는 각각 26,22,19 및 16이었고, 상압에서 S$_2$O$_3^{2-}$, SCN$^-$, I$^-$ 및 NO$_2^-$이온일 때 ${\Delta}$V(cm$^3$/mole)는 각각 26, 30, 64 및 45이었다. S$_2$O$_3^{2-}$이온인 경우 Fuoss식에 의하여 계산한 평형상수와 실험치를 비교하여 Cu(Ⅱ) 착이온과 L$^{n-}$간의 결합성을 고찰하였다.