• Analytical Science and Technology
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• 제13권3호
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• pp.385-393
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• 2000

A gas chromatography-mass spectrometric (GC/MS) procedure for the determination of amineptine (dihydro-10, 11-dibenzo[a, d] cycloheptenyl-5-amino-7-heptanoic acid) and its main metabolites in human urine was described. Amineptine has been known to be extensively metabolized by the ${\beta}$-oxidation of the heptanoic side chain with formation of pentanoic side chain metabolite ($C_5$-metabolite), and lactamizarion by internal dehydration of (${\beta}$-oxidized metabolite (${\delta}$-lactam). The detection of these compounds was based on acid hydrolysis, liquid-liquid extraction and trimethylsilylated derivatization of the carboxylic acid group. For the determination of amineptine and its metabolites in biological fluids, selected ions at the m/ 192, molecular ion and one of the characteristic ions were monitored by GC/MS. On the excretion study of amineptine in human urine, 70-90% of amineptine, ${\delta}$-lactam, and $C_5$-metabolite were found to be excreted within 4 hours and their excretion completed within 20 hours.

• Korean Journal of Microbiology
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• 제25권2호
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• pp.157-164
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• 1987

A new endo-$\beta$-1, 4-glucanase was purified from the culture filtrate of thermophilic anaerobic Clostridium thermocellum. The purification procedure included two steps of ion exchange chromatography with DEAD-Sephadex A-50 and gel filtration chromatography with Sephadex G-75. Even though the 56 fold increase in CMCase specific activity was obtained, the actually recovered enzyme activity was relatively lower level of 0.7%. Judging from the two bands in SDS-polyacrylamide gel electrophoresis, the endo-$\beta$-1, 4-glucanase consists of two subunits whose M.W. are 38,000 and 58,000, respectively. The optimum pH and temperature were determined to be 5.0 and $65^{\circ}C$, respectively. The enzyme was stable up to $70^{\circ}C$, but inactivated at $80^{\circ}C$. The kinetic parameters of the separated fraction were also determined. The purified enzyme did not show any significant hydrolytic activity against the highly ordered crystalline cellulose as well as filter paper.

• Journal of Life Science
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• 제15권1호
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• pp.94-99
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• 2005

Sixty four bacterial colonies which were able to oxidize the manganese were isolated from soil samples in Mokcheon and Ochang area. Among them, one bacterial strain was selected for this study based on its higher manganese oxidation, and this selected bacterial strain was identified as Aeromonas sp. MN44 through physiological-biochemical test and analysis of its 16s rRNA sequence. Aeromonas sp. MN44 was able to utilize lactose but did not utilize various carbohydrates as a sole carbon source. Aeromonas sp. MN44 showed a very sensitive to antibiotics such as kanamycin, chloramphenicol, ampicillin, tetracycline and spectinomycin, and heavy metal such as cadmium. But this strain showed a high resistance up to mg/ml unit to heavy metals such as lithium and manganese. Optimal manganese oxidation condition of Aeromonas sp. MN44 was pH 7.4 and manganese oxidation activity was inhibited by proteinase K and boiling treatment. So, we concluded that this factor was protein. The manganese oxidizing factor produced by Aeromonas sp. MN44 was partial purified by ammonium sulfate precipitation, DEAE-Toyopearl 650M ion exchange chromatography and Sephadex gel filtration chromatography. Its molecular mass was about 113 kDa.

• Journal of Life Science
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• 제14권5호
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• pp.794-799
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• 2004

Cyclodextrin glucanotransferase (CGTase) produced by Bacillus subtilis NAl/pKBl was used for the production of cyclodextrin (CD). The enzyme was purified by ion exchange and gel filtration chromatography. The purified enzyme exhibited its maximum activity in the pH range of 6.0 to 7.0 and temperature range of 60 to $70^{\circ}C$. Immobilization of purified CGTase was carried out with various immobilization matrices. Amberlite IRA-900, a strong basic anion exchange resin, showed the highest immobilization ability (38 units per gram resin). Optimal pH and temperature for enzymatic reaction of the immobilized CGTase were pH 6.0 and 60t. The activity of immobilized CGTase maintained more than a month and could be reused for a month in a continuous enzyme reactor for the production of CD.

• Korean Journal of Veterinary Service
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• 제27권1호
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• pp.17-29
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• 2004

A multiresidual analysis was performed to determine 12 sulfonamides(sulfacetamide, sulfadiazine, sulfisomidine, sulfathiazole, sulfapyridine, sulfamerazine, sulfamethazine, sulfamonomethoxine, sulfisoxazole, sulfamethoxazole, sulfaquinoxaline, and sulfadimethoxine) in beef and pork simultaneously. The multiresidual analysis for the sulfonamides currently used was able to analyze 5 kinds of sulfonamides at the same time. The method of this 12 sulfonamides multiresidual analysis in this study was matrix solid-phase dispersion(MSPD) by high performance liquid chromatography (HPLC) and liquid chromatography mass spectrometry (LC/MS). The recovery rate of the materials was measured by MSPD method with 3 different extraction solvents; Dichloromethane, DCM: Ethylacetate(3:1), DCM:EA(9:1). Also, samples (84 beef and 205 pork samples) which were positive by EEC-4 plate test from 2001 to 2003 were tested to investigate the kinds of sulfonamides using HPLC. The results from the study were as follows; 1. The recovery rate of the materials was measured by MSPD method with 3 different extraction solvents; Dichloromethane, DCM:Ethylacetate(3:1), DCM:EA(9:1). The method of extraction solvent with DCM:ethyl acetate(9:1) was the most excellent(87.7∼99.3%) in separation and reappearance. 2. In the LC/MS analysis. of sulfonamides, signal to noise ratio was showed relatively high in the positive mode and special ion in the quality analysis was determined via [M+H]$\^$+/ and m/z 156. A spectrum of sulfonamides was showed from all 12 sulfonamides. 3. The samples positive by the EEC-4 plate, a screening test method, were categorized by sulfonamides through Charm II and confirmed the kinds of sulfonamides through HPLC. 1) Among 84 beef samples positive by EEC-4 plate, 20 samples were positive by Charm II and identified as 7 sulfamethazine, 9 sulfadimethoxine, 1 sulfamonomethoxine and 3 unknown status. 2) Among 205 pork samples positive by EEC-4 plate, 42 samples were positive by Charm II and identified as 19 sulfamethazine, 1 sulfadimethoxine, 4 sulfamonomethoxine and 5 unknown status.

• Journal of Korean Society on Water Environment
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• 제32권6호
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• pp.649-669
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• 2016

This study explored the analytical conditions for 21 veterinary antibiotics which have been popularly sold in South Korea in 2014 but have not yet been targeted in EPA method 1694. Most of the selected antibiotics were separated by a reverse-phase C18 column with a combination of (buffered) water and organic polar solvent, which was commonly methanol and acetonitrile in the gradient elution mode. Volatile additives such as formic acid, ammonium acetate and ammonium formate were usually added to the mobile phases to minimize asymmetrical and tailing of antibiotics' peaks and to increase their ionization in mass spectrometry. The analytical methods of aminoglycoside antibiotics were distinct from those of the other antibiotics in terms of adoption of ion-pair chromatography (IPC) and hydrophilic interaction liquid chromatography (HILIC) capable of retaining and separating extremely polar compounds due to their hydrophilicity. Trifluoroacetic acid or heptafluorobutyric acid was frequently added to the mobile phase as an ion-pair reagent for the IPC. Tandem mass spectrometry was numerously applied to the detection of antibiotics using positive electrospray ionization (ESI) and the selected reaction monitoring (SRM) mode. All reviewed analytical methods had been/were validated by evaluating recovery, limits of detection and quantification, decision limit or detection capability of the methods.

• Journal of the Korean Chemical Society
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• 제43권3호
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• pp.280-285
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• 1999

Separation of plutonium species was studied by ion chromatography installed in a glove box for the determination of plutonium element. The plutonium species, $PuO_2^{2+},\; PC^{4+}\; and\; Pu^{3+}$, were stably separated on dynamically equilibrated cation exchanger using 1-octanesulfonate and ${\alpha}$-HiBA eluant after controlling the plutonium oxidation states with KI, $NaNO_2\;or=;KBrO_3$ based on the oxidation-reduction potentials. For the separation of plutonium from other matrix, $PuO_2^{2+}\; and\; Pu^{4+}$ were reduced to $Pu^{3+}$ with KI and $NaNO_2$ followed by cation exchange chromatography.

• Journal of the Korean Chemical Society
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• 제29권2호
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• pp.178-182
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• 1985

The purpose of this study was to develop a separation method of Zn(II), Cu(II) and Mg(II), by ion exchange chromatography using cation exchange resion (Dowex 50w${\times}$8, 80-100 mesh) and anion exchange (Amberlite IRA-400). Ion exchange resions were packed into 25 ${\times}$ 2cm ID column and flow rate was controlled to 0.30 ml/min. Good eluents for separation of nonferrous metal ions such as Zn(II), Cu(II), Mg(II) were as follow: 0.5M $NaNO_3$ (pH 3.1), 0.2~0.5M HCl + 50~60% Acetone, and 1M HAc + 0.1M NaAcf(pH 3.7) aqueous solution. The mixed solution of 0.1M NaAc(pH 3.7), 0.5M HCl + 50% Acetone were found to be the best eluent for step elution. Analysis of metals were determined by atomic absorption spectrophotometer. In addition, separated Zn(II) fraction was obtained by eluted with 0.12N HCl and 1.5N $NH_4OH$ aqueous solution. This solution was titrated by the E. D. T. A.

• Journal of the Korean Chemical Society
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• 제41권5호
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• pp.256-265
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• 1997

A rapid and sequential method was studied, which can determine nitrite, nitrate and ammonium ion in soil or water samples with flow injection analysis. Geometric factors including injection volume, length of the reaction coil and flow rate of carrier solution were investigated prior to sample measurement. Nitrite was determined at 540 nm by Griess reaction producing azo dye between N-(1-naphthylethylenediamine dihydrochloride) and sulfanilamide. Nitrate was also measured under the help of reduction mechanism toward nitrite with hydrazine. Ammonium was analyzed at 440 nm with Nessler's reagent. At the optimum condition, the detection limit(S/N=3) has been shown 0.1 ㎍/mL N(NO2-), 0.4 ㎍/mL N(NO3-) and 0.3 ㎍/mL N(NH4+) respectively. The results measured by colorimetry, ion chromatography and FIA were compared showing 80%-125% reasonable match each other. Injection throughput rate could be performed better than 30 times per hour.

• Analytical Science and Technology
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• 제10권4호
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• pp.231-239
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• 1997

We developed a procedure that can effectively separate and determine tertiary amines and quaternary ammonium salts in some samples with reverse phase ion-pair high performance chromatography, employing indirect spectrophotometric detection method. Detection and ion-pairing reagents used in this study were benzyl trimethylammonium chloride (BTMACl) and sodium dodecyl sulfate(DDSANa), respectively. Eluting the electrolyte solutions of some commercial electrolytic capacitors with a MeOH(40):water(60) eluent (pH 8.5 adjusted with NH4Cl-NH3 buffer) containing 0.010M DDSANa and 0.004 M BTMACl through Supelco LC-18 or ${\mu}$-Bondapak phenyl column, amines and ammonium salts contained in the sample were successfully separated and determined. Varying the composition, especially the content of quaternary ammonium salts, of electrolyte solutions based on this analysis. we could prepare the low impedance(0.08~0.13) electrolytic capacitors with excellent electrical properties and it was a confirmation that the analysis is favorable.