• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.1
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• pp.276.1-276.1
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• 2003

This study describes a simple and sensitive semi-micro HPLC method with UV detection and direct deproteinization. The plasma protein was precipitated using perchloric acid (60％) and the supernatant was directly injected onto the semi-micro HPLC system. The separation was achieved on a C18 (25 mm ${\times}$ 2.0 mm I.D) analytical column with a mobile phase of sodium acetate buffer (pH 3.5, 50 mmol) - acetonitrile (60:40, V/V). (omitted)

• Archives of Pharmacal Research
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• 제21권2호
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• pp.217-222
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• 1998

A stereospecific HPLC method has been developed for the resolution of the enantiomers of salbutamol in human urine. After solid-phase extraction and derivatization with 2,3,4,6-tetra-O-acetyl-$\beta$-D-glucopyranosyl isothiocyanate, the diastereomeric derivatives were resolved (Rs=1.83) on $5{\mu}m$ octadecylsilan column using 35% acetonitrile in 0.05M ammonium acetate buffer (pH=6) as a mobile phase with electrochemical detection. The diastereomeric derivatives were formed within 30 min. The detection limit of each enantiomer was 20 ng/ml (S/N=3).

• Journal of Photoscience
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• 제4권3호
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• pp.105-112
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• 1997

The fluorescence quenching of 2, 5-di-(5-tert-butyl-2-benzoxazolyl)-thiophene (BBOT) by aniline in five different solvents namely heptane, hexane, cyclohexane, dioxane and acetonitrile has been carried out at room temperature with a view to understand the quenching mechanisms. The experimental results show positive deviation in the Stern-Volmer plots in all the solvents. In order to interpret these results we have invoked the Ground state complex and sphere of action static quenching models. Using these models various rate parameters have been determined. The magnitudes of these parameters suggest that sphere of action static quenching model agrees well with the experimental results. Hence this positive deviation is attributed to the static and dynamic quenching. Further, with the use of Finite Sink approximation model, it was possible to check these bimolecular reactions as diffusion-limited and to estimate independently distance parameter R$^1$ and mutual diffusion coefficient D. Finally an attempt has been made to correlate the values of R$^1$ and D with the values of the encounter distance R and the mutual diffusion coefficient D determined using the Edward's empirical relation and Stokes-Einstein relation.

• Bulletin of the Korean Chemical Society
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• 제7권1호
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• pp.45-50
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• 1986

Separation of optical isomers of some derivatives of amino acids by reversed-phase HPLC has been accomplished by adding a chelate of an optically active amino acid to copper(Ⅱ) to the mobile phase. Cu(Ⅱ) complexes of L-proline and L-hydroxyproline in the mobile phase showed different degrees of separation. Optical isomers of DNS derivatives of amino acids are selectively separated, but those of several other derivatives are not at all. The kinds of buffer agents, the pH, and the concentrations of acetonitrile and the Cu(Ⅱ) ligand all affect the separations. The elution behavior between D and L DNS-amino acids appears to depend on the alkyl side chain of the amino acids. A chromatographic mechanism is proposed that is based on a stereospecificity of the formation of ternary complexes by the D, L-DNS-amino acids and the chiral additive associated with the stationary phase. The steric effects of the ligand exchange reactions are related with the feasibility of cis and/or trans attack of the amino acids to the binary chiral chelate retained on the stationary phase.

• 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.223.1-223.1
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• 2003

D-Amygdalin and its conversion product, neoamygdalin, were clearly separated on reverse-phase column chromatography by an optimized eluent of 10 mM sodium phosphate buffer (pH 3.5) containing 8.5% acetonitrile. Linearity for analyzing D-amygdalin and neoamygdalin was observed in the range from 0.05 to 0.5 mM. The detection limits for D-amygdalin and neoamygdalin were ca. 5 uM per injected amount. When extracting amygdalin from a whole piece of Armeniacae Semen in the boiling aqueous solution, there was almost no influence of emulsin; it resulted in higher extraction yield. (omitted)

• Bulletin of the Korean Chemical Society
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• 제26권4호
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• pp.641-644
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• 2005

Nucleophilic addition reactions of benzylamines $(XC_6H_4CH_2NH_2)\;to\;{\beta}$-cyanostilbenes ($YC_6H_4CH=C(CN)C_6H_4$Y’) have been studied in acetonitrile at 30.0 oC. A greater degree of N-$C_{\alpha}$ bond formation (larger ${\beta}_X$) is obtained with a stronger electron-withdrawing substituent in either ${\alpha}-\;(\delta\sigma_Y\;{\gt}\;0)\;or\;{\beta}-ring\;(\delta\sigma_{Y'}\;{\gt}$ 0). A stronger charge development is observed in the TS on $C_{\beta}\;(\rho_{Y'}$= 1.06 for X=Y=H) rather than on $C_{\alpha}\;(\rho_{Y}$ = 0.62 for X=Y’H) indicating the lag in the resonance development into the activating group (CN) on $C_{\beta}$ in the transition state. Similarly, the magnitude of $\rho$$_{XY'}$(−0.72) is greater than $\rho_{XY}$ (−0.66) due to a stronger interaction of the nucleophile with $\beta$-ring than $\alpha$-ring. The positive sign of $\rho_{YY'}$correctly reflects $\pi$ bond cleavage between the two rings in the TS. Relatively large kinetic isotope effects ($k_H/k_D\;{\geq}$ 2.0) involving deuterated nucleophiles ($XC_6H_4CH_2ND_2$) suggest a four-membered cyclic TS in which concurrent N-C$_{\alpha}$ and H(D)-C$_{\beta}$ bond formation occurs.

• Bulletin of the Korean Chemical Society
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• 제32권12호
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• pp.4185-4190
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• 2011

The nucleophilic substitution reactions of ethylene phosphorochloridate (1c) with substituted anilines ($XC_6H_4NH_2$) and deuterated anilines ($XC_6H_4ND_2$) are investigated kinetically in acetonitrile at $5.0^{\circ}C$. The anilinolysis rate of 1c involving a cyclic five-membered ring is four thousand times faster than its acyclic counterpart (1a: diethyl chlorophosphate) because of great positive value of the entropy of activation of 1c (${\Delta}S^{\neq}=+30\;cal\;mol^{-1}K^{-1}$ compared to negative value of 1a (${\Delta}S^{\neq}=-45\;cal\;mol^{-1}K^{-1}$) over considerably unfavorable enthalpy of activation of 1c (${\Delta}H^{\neq}=27.7\;kcal\;mol^{-1}$) compared to 1a (${\Delta}H^{\neq}=8.3\;kcal\;mol^{-1}$). Great enthalpy and positive entropy of activation are ascribed to sterically congested transition state (TS) and solvent structure breaking in the TS. The free energy correlations exhibit biphasic concave upwards for substituent X variations in the X-anilines with a break point at X = 3-Me. The deuterium kinetic isotope effects are secondary inverse ($k_H/k_D$ < 1) with the strongly basic anilines and primary normal ($k_H/k_D$ > 1) with the weakly basic anilines and rationalized by the TS variation from a dominant backside attack to a dominant frontside attack, respectively. A concerted $S_N2$ mechanism is proposed and the primary normal deuterium kinetic isotope effects are substantiated by a hydrogen bonded, four-center-type TS.

• 분석과학
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• 제19권6호
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• pp.519-528
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• 2006

본 연구에서는 뇨시료를 고체상 추출법으로 추출한 후 HPLC/DAD/ESI-MS(high-performance liquid chromatograph/diode array detector/electro-spray ionitation mass spectrometry)를 사용하여 분석하였다. 7종의 thyroid hormones의 HPLC 분리조건은 Hypersil ODS(octadecylsilica) 컬럼(4.6mm I.D., 100 mm length, particle size $5{\mu}m$)을 사용하고 ammonium formate buffer와 acetonitrile을 이동상으로 하여 기울기 용리한 결과 완전 분리가 가능하였으며, UV spectra 및 질량스펙트럼을 확인할 수 있었다. 고체상 추출법에 의한 전처리 최적 조건을 조사한 결과 시료를 pH 3으로 한 후 C18 고체상을 사용하여 4 mL의 methanol/ammonium hydroxide(9:1) 혼합용액으로 용리할 경우 회수율이 89.0-113.1%로 나타났다. HPLC/DAD를 이용하여 10-1000 ng/mL범위에서 검량선을 작성한 결과 $r^2$값은 0.992-0.998 으로 나타났으며 검출한계는 2-4 ng/mL(3.8-13.0 pmol/mL)로 계산되었다.

• Natural Product Sciences
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• 제23권4호
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• pp.270-273
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• 2017

A quantitative analysis of bakkenolide D in the different parts of Petasites japonicus and Farfugium japonicum was performed by HPLC. A gradient HPLC elution system with a mobile phase consisting of water: acetonitrile solution (20:80 to 0:100 for 45 min) was followed and an INNO $C_{18}$ column was used for the chromatographic separation. The injection volume, flow rate, and UV detection were $10{\mu}L$, 1 mL/min, and 290 nm, respectively. Results show that both species showed the highest amount of bakkenolide D in the roots being 107.203 and 166.103 mg/g for P. japonicas and F. japonicum, respectively. Content analysis on the different parts of both plants displayed remarkably lower values which ranged from 0.403 - 4.419 and 7.252 - 32.614 mg/g for P. japonicas and F. japonicum, respectively. The results show that the roots of both plants are rich in bakkenolide D showing a promising use in the development of nutraceuticals and industrial application of the compound.

• Bulletin of the Korean Chemical Society
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• 제33권2호
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• pp.597-600
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• 2012

Polyynes were formed by laser ablation of a graphite target in deionized water ($H_2O$ and $D_2O$) and various organic solvents such as acetonitrile, n-hexane, and c-hexane and were identified by analyzing ultraviolet (UV) absorption and Raman spectra. We assigned the major UV absorption peaks that coincided with the electronic transitions corresponding to linear polyyne chains. The UV absorption peak intensities of a polyyne solution decreased as the holding temperature of the solution increased. Also, the absorption spectra of polyynes obtained by laser ablation of a graphite target at different volume fractions of $H_2O$ and $D_2O$ were examined.