• Journal of the Korean Chemical Society
• /
• v.59 no.3
• /
• pp.225-232
• /
• 2015

A liquid chromatography-electrospray ionization-tandem mass spectrometry method (LC-ESI-MS/MS) was used for determining seven pesticides (2,4-dichlorophenoxyacetic acid, methomyl, aldicarb, 2-methyl- 4-chlorophenoxy- acetic acid, molinate, carbaryl and carbofuran) and two synthetic materials (quinoline and bisphenol-A) in surface water. The analytes were extracted using solid-phase extraction (SPE). The eluate was concentrated by nitrogen gas. 100 microliters of 30% (v/v) methanol aqueous solution were used to dissolve the residue and an aliquot of the reconstituted solution was directly injected into LC-ESI-MS/MS after the filtration using 0.2 μm polytetrafluoroethylene (PTFE) syringe filter. Under the established condition, the calibration curves of the analytes were linear with correlation coefficients of above 0.997. The quantification limit was 0.002~0.011 μg/L and the relative standard deviations were less than 16.4%. In addition, accuracy was in the range of 84~107% and the recoveries were values between 56.2 and 98.6%. In this study, the developed method was applied to the analysis of real surface water samples.

• Analytical Science and Technology
• /
• v.17 no.3
• /
• pp.263-270
• /
• 2004

A method is described for the analysis of short-chain alkylphenol ethoxylates (APEOs), 4-octylphenol-di-ethoxylate (OP2EO) and 4-nonylphenol-di-ethoxylate (NP2EO), in drinking water or wastewater using reversed phase high-performance liquid chromatography with electrospray ionization mass spectrometry. The solvent system was water and methanol containing $10{\mu}M$ trifluoroacetic acid as an ionization solvent. We acidified 1 L of water samples to less than pH 2 with concentrated $H_2SO_4$ and loaded onto Sep-Pak $C_{18}$, and eluted with acetone. The calibration of OP2EO and NP2EO was performed for the concentration range from 20 to 500 ng/L and the correlation coefficients were 0.999 and 0.990, respectively. The limits of detection were 20 ng/L (OP2EO) and 50 ng/L (NP2EO) at a signal-to-noise ratio of 3. Accuracy and precision of this analytical method were 85.8 ~ 122.1% and 8.2 ~ 18.8%, respectively. The proposed method allowed a sensitive and rapid detection of OP2EO and NP2EO and it could be applied for monitoring of APEOs from environmental samples.

• Korean Journal of Social Welfare Studies
• /
• no.39
• /
• pp.365-393
• /
• 2008

This research examnied the roles, the strategies and the influence of labor unions on the pension reform. In Italia labor unions were important actors in pension reform politics during 1990s, but in 2004 labor union was excluded from the pension reform. This difference is not only related with diffusion of the leftist party but also the experience of pension benefit retrenchment of the pension reform in 1995 in which labor unions had initiatives. Labor unions choose their strategies, social dialogue or mass struggle, depending on the attitudes of government. After change of government following the failure of the pension reform in 1994 Italian government tried social dialogue. In Dini reform in 1995, laborunions had initiative in making pension reform plan. Labor unions obtained member's approval using membership vote. It had repressed opposition from militant sectors effectively. However Labor unions concentrated on the issues of transition measures and protecting vested rights in seniority pension ignoring problems of contribution evasion of small-firm workers and benefit adequacy of young workers. Even when labor unions leaded social concertation processes and pursued union democracy, labor unions' influences on the pension reform had fundamental limitations.

• Analytical Science and Technology
• /
• v.19 no.2
• /
• pp.149-154
• /
• 2006

A gas chromatography-mass spectrometric method was developed for the determination of formaldehyde in urine and saliva. In a 20 mL glass tube, 0.2 mL of urine or saliva was taken. Further, 1.8 mL of 0.1 M HCl, 0.1 mL of 2,000 mg/L 2,4-dinitrophenyl hydrazine and $20{\mu}l$ of 500 mg/L acetone-$d_6$ as internal standard were added in the tube and sealed tightly with cap. The solution was shaken for 20 min at room temperature and extracted using 4 mL of toluene. The extract was concentrated and redissolved with $100{\mu}l$ of acetonitrile, and then measured by gas chromatography-mass spectrometer (selected ion monitoring). The detection limit was 2.0 ng/mL and 0.5 ng/mL in saliva and urine, respectively. The calibration curves showed good linearity with r = 0.997 and 0.998 for saliva and urine, respectively. The method was used to analyze formaldehyde in rat urine after oral exposure. The developed method may be use ful to the monitoring for formaldehyde exposure in human.

• Journal of the Korean Chemical Society
• /
• v.61 no.4
• /
• pp.143-150
• /
• 2017

Countercurrent oxidation process (COP) was developed and evaluated for treatment of highly concentrated PCB containing insulating oil. The PCB content in insulating oil taken from Haksanmetal company was found to be 1,512 ppm. The COP utilizes a self-sustained flame which propagates itself in a direction counter to the oxygen flow. The flame removes PCBs adsorbed in activated carbon and, at the same time, regenerates activated carbon. The flame temperature was determined from both mass loss of activated carbon and the relative ratio of CO and $CO_2$ exhausted during COP, and showed that its temperature lied in the range of $650-850^{\circ}C$. Removal efficiency of PCBs was achieved above 99.99% for 5% of insulating oil loaded activated carbon with 1 COP in weight ratio. Also, the same removal efficiency was acquired for 60% of insulating oil loaded activated carbon with three consecutive COP. In addition, specific surface area of activated carbon during COP was recovered to almost similar value of virgin activated carbon. It proved that the COP was much effective in removing high concentration of PCBs in insulating oil easily and affordably.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.4
• /
• pp.581-588
• /
• 2007

To enhance the photodecomposition of concentrated ammonia into N2, Pt/V-TiO2 photocatalysts were prepared using solvothermal and impregnation methods. Nanometer-sized particles of 0.1, 0.5 and 1.0 mol% V-TiO2 were prepared solvothermally, and then impregnated with 1.0 wt% Pt. The X-ray diffraction (XRD) peaks assigned to V2O5 at 30.20 (010) and Pt metal at 39.80 (111) and 46.20 (200) were seen in the 1.0 wt% Pt/ 10.0 mol% V-TiO2. The particle size increased in the order: pure TiO2, V-TiO2 and Pt/V-TiO2 after thermal treatment at 500 °C, while their surface areas were in the reverse order. On X-ray photoelectron spectroscopy (XPS), the bands assigned to the Ti2p3/2 and Ti2p1/2 of Ti4+-O were seen in all the photocatalysts, and the binding energies increased in the order: TiO2 < Pt/V-TiO2 < V-TiO2. The XPS bands assigned to the V2p3/2 (517.85, 519.35, and 520.55 eV) and V2p1/2 (524.90 eV) in the V3+, V4+ and V5+ oxides appeared over V-TiO2, respectively, while the band shifted to a lower binding energy with Pt impregnation. The Pt components of Pt/ V-TiO2 were identified at 71.60, 73.80, 75.00 and 76.90 eV, which were assigned to metallic Pt 4f7/2, PtO 4f7/2, PtO2 4f7/2, and PtO 4f5/2, respectively. The UV-visible absorption band shifted closer towards the visible region of the spectrum in V-TiO2 than in pure TiO2 and; surprisingly, the Pt/V-TiO2 absorbed at all wavelengths from 200 to 800 nm. The addition of vanadium generated a new acid site in the framework of TiO2, and the medium acidic site increased with Pt impregnation. The NH3 decomposition increased with the amount of vanadium compared to pure TiO2, and was enhanced with Pt impregnation. NH3 decomposition of 100% was attained over 1.0 wt% Pt/1.0 mol% V-TiO2 after 80 min under illumination with 365 nm light, although about 10% of the ammonia was converted into undesirable NO2 and NO. Various intermediates, such as NO2, -NH2, -NH and NO, were also identified in the Fourier transform infrared (FT-IR) spectra. From the gas chromatography (GC), FT-IR and GC/mass spectroscopy (GC/MS) analyses, partially oxidized NO and NO2 were found to predominate over V-TiO2 and pure TiO2, respectively, while both molecules were reduced over Pt/V-TiO2.

• Journal of Microbiology and Biotechnology
• /
• v.11 no.4
• /
• pp.636-643
• /
• 2001

Bacillus sp. AIR-5, a strain from soil, produced an extracellular maltopentaose-forming amylase from amylose and soluble starch. This bacterium produced 8.9 g/l of maltopentaose from 40 g/l of soluble starch in a batch fermentation and the maltopentaose made up 90 % of the maltooligosaccharides produced (from maltose to maltoheptaose). The culture supernatant was concentrated using a 30 K molecular weight cut-off membrane and purified by DEAE-Cellulose and Sephadex G-150 column chromatographies. The purified protein showed one band on a native-PAGE and its molecular mass was estimated as 250 kDa. The 250-kDa protein was composed of tetramers of a 63-kDa protein. the isoelectric point of the purified protein was pH 6.9, and the optimum temperature for the enzyme activity was $45^{\circ}C$. The enzyme was quickly inactivated above $55^{\circ}C$, and showed a maximum activity at pH 8.5 and over 90% stability between a pH of 6 to 10. The putative N-terminal amino acid sequence of AIR-5 amylase, ATINNGTLMQYFEWYVPNDG, showed a 96% sequence similarity with that of BLA, a general liquefying amylase.

• Journal of Korean Society of Steel Construction
• /
• v.17 no.5 s.78
• /
• pp.537-547
• /
• 2005

MABB(Editor's note: Please spell out "MABB" upon first mention)is a new structural type of arch that connects arch ribs and stiffened girders with two internal arches. In this study, the static and dynamic behavior of MABB were analyzed in comparison with those of conventional arches for the investigation of the structural effect of MABB on moving loads. For the purpose of surveying the effect of internal arches on the dynamic behavior of structure, natural frequency and natural vibration mode were investigated and the static and dynamic behavior were analyzed by the method of idealizing train loads as traveling loads consisting of a group of concentrated loads. From the results, the following conclusions were known. First, it is concluded that with MABB, decreasing the section of stiffened girders is possible as compared with conventional arches because the increase of stiffness by internal arches is larger than that of the mass of internal arches. Second, MABB has the advantage of assurance of stability of dynamic behavior because the dynamic behavior of MABB on moving loads is usually investigated in a more stable way than that of conventional arches.

• Journal of Life Science
• /
• v.22 no.7
• /
• pp.981-986
• /
• 2012

To produce a new tea with a good flavor and functional properties using green tea of low quality, naked barley and barley were selected to blend with the green tea. The simultaneous distillation extraction method (SDE) using Likens and Nickerson's extraction apparatus was used to extract the volatile flavor compounds from the samples. The concentrated flavor extracts were analyzed and identified by GC and GC-MS. The GC patterns of the flavor components in two parched barleys were very different. The main volatile flavor components in two of the samples were alkyl pyrazines. Compounds including 3-methylbutanal, 2-methylbutanal, dihydro-2-methyl-3(2H)-furanone, 2,5-dimethyl pyrazine, and 3-ethyl-2.5-dimethyl pyrazine were isolated from the naked barley. Compounds including thiophenes, thiazoles, sulfides, and pyrroles with burnt odor were isolated from the barley. The parched naked barley was better than barley for adding to green tea. The main aroma components of the green tea blended with the naked barley were hexanol, hexanal, trans-2-hexenal, ${\beta}$-ionone, ${\alpha}$-ionone, alkyl pyrazines, 3-methylbutanal, 2-methylbutanal, and furfural.

• Journal of the East Asian Society of Dietary Life
• /
• v.22 no.5
• /
• pp.642-648
• /
• 2012

In the present study, yakju was developed added with 100~400 g of meoru (Vitis coignetiae). We analyzed the volatile flavor compounds and investigated the sensory properties of meoru yakju. The volatile flavor compounds were isolated from in fusions by Porapak Q column adsorption. The concentrated flavor extract was analyzed and identified by GC (gas chromatography) and GC-MS (gas chromatography-mass spectrometry) analyses. Thirty-five compounds, including five alcohols, nine esters, seven acids, four hydrocarbons, three ketones, and seven other compounds, were identified. The total number and content of volatile flavor compounds in control yakju were the highest, but they decreased as the amount of added meoru increased. On the other hand, yakju containing 200 g of meoru was characterized by the highest content of ester compounds, and it was the most preferred in terms of flavor, color, taste, and over all acceptability. Based on these results, addition of 200 g of meoru to 1,715 g of control yakju was determined to be the optimal condition for making meoru yakju.