• Applied Chemistry for Engineering
• /
• v.23 no.5
• /
• pp.505-509
• /
• 2012

In this study, we investigate the use of new carbon nanotube paste electrode (CNPE) for promoting the detection of lead (Pb) heavy metal in the a drinkable water, which negatively affects human brain and nerve system. For the evaluations, CNPE is served as a working electrode, while sensitivity and limit of detection (LOD) of Pb are measured in DI and tap water based electrolytes using squarewave anodic stripping voltammetry (SWASV). As a result of that, in the 25~150 ppb range of $Pb^{2+}$ ions, its sensitivity and calculated LOD are $12.85\;{\mu}A/{\mu}M$ and 26 ppb in DI water based 0.1 M $H_{2}SO_{4}$ electrolyte while they are $10.36\;{\mu}A/{\mu}M$ and 38 ppb electrolytes respectively. In addition, experimentally measured LOD values of Pb are 4 ppb and 10 ppb in the two water electrolytes. The stripping of $Pb^{2+}$ ion is also controlled by surface reaction. Our experimental data are then compared with those of other already published references. With the comparison, it is proved that our electrode outperforms other electrodes in terms of the sensitivity and LOD of trace Pb metal.

• Korean Journal of Microbiology
• /
• v.40 no.4
• /
• pp.320-327
• /
• 2004

Three hundreds thirty two bacterial colonies which were able to degrade crude oil were isolated from soil sam­ples that were contaminated with oil in Daejeon area. Among them, one bacterial strain was selected for this study based on its higher oil degrading ability, and this selected bacterial strain was identified as Acinetobactor sp. B2 through physiological-biochemical tests and analysis of its 16S rRNA sequence. Acinetobactor sp. B2 was able to utilize various carbohydrates but did not utilize trehalose and mannitol as a sole carbon source. Acinetobactor sp. B2 showed a weak resistance to antibiotics such as kanamycin, streptomycin, tetracycline and spectinomycin, but showed a high resistance up to mg/ml unit to heavy metals such as Ba, Li, Mn, AI, Cr and Pb. The optimal growth temperature of Acinetobactor sp. B2 was $30^{\circ}C.$ The lipase produced by Acinetobactor sp. B2 was purified by ammonium sulfate precipitation, DEAE-Toyopearl 650M ion exchange chromatography and Sephadex gel filtration chromatography. Its molecular mass was about 60 kDa and condition for the optimal activity was observed at $40^{\circ}C$ and pH 10, respectively. The activation energy of lipase for the hydrolysis of p­nitrophenyl palmitate was 2.7 kcal/mol in the temperature range of 4 to $37^{\circ}C,$ and the enzyme was unstable at the temperature higher than $60^{\circ}C.$ The Michaelis constant $(K_m)\;and\;V_{max}$ for p-nitrophenyl palmitate were 21.8 uM and $270.3\;{\mu}M\;min^{-1}mg^{-1},$ respectively. This enzyme was strongly inhibited by 10 mM $Cd^{2+},\;Co^{2+},\;Fe^{2+},\;Hg^{2+},$ EDTA and 2-Mercaptoethalol.

• Korean Journal of Microbiology
• /
• v.40 no.4
• /
• pp.269-274
• /
• 2004

Serratia proteamaculans isolated from the midgut of a spider formed big halos around the bacterial colonies, indicating that the bacterial strain produces an extracellular protease. Activity staining of the extracellular pro­tein fractions using zymogram also demonstrated that the major protein with an estimated molecular mass of 52 kDa contained a high proteolytic activity. The protease was purified to near electrophoretic homogeneity from the culture supernatant after filtration and ion exchange and size exclusion chromatography. The purified enzyme had a relatively high proteolytic activity between pH 6.0 and 10.0 and at broad temperature range. The proteolytic activity of the enzyme was not inhibited by phenylmethylsulfonyl fluoride but strongly inhibited by 1, 10-phenanthroline and EDTA. The activity also was dependent on the presence of $Ca^{++}\;and\;Zn^{++}$ ions. These observations indicate that the enzyme is a metalloprotease.

• Analytical Science and Technology
• /
• v.12 no.3
• /
• pp.190-195
• /
• 1999

The metabolism of testosterone ($17{\beta}$-hydroxy-androst-4-en-3-one) was confirmed in horse after a single intramuscular administration of testosterone cypionate (750 mg). Solvent extracts of urine obtained with enzymatic hydrolysis and methanolysis were analyzed by GC/MS after oxime t-butyldimethylsilyl (oxime-TBDMS) derivatization. The structures of four urinary metabolite after testosterone administration in horse were determined based on EI mass spectra and $5{\alpha}$-androstane-$3{\beta}$, $17{\alpha}$-diol and $5{\alpha}$-androstane-$3{\beta}$-ol-17-one as major was confirmed with authentic standard. Also the concentrations of $5{\alpha}$-androstane-$3{\beta}$, $17{\alpha}$-diol, $5{\alpha}$-androstane-$3{\beta}$, $17{\beta}$-diol, dehydroepiandrosterone (DHEA), $5{\alpha}$-androstane-$3{\beta}$-ol-17-one and testosterone were determined in the urine of normal subjects and the urine after administration. The recovery and detection limit in the most drugs were 86.3~94.7% and 1~3 ppb, respectively. Correlation coefficients for calibration were in the range of 0.984~0.999. Excretion profile of testosterone presents the rapid and large increasement up to maximum values at days 5 after administration and the slow regression. The relative ratios of testosterone, its metabolites over DHEA were determined for indication of testosterone administration in horse doping.

• Journal of Sensor Science and Technology
• /
• v.9 no.1
• /
• pp.22-27
• /
• 2000

Amorphous FeCoSiB films with high saturation magnetostriction and excellent soft magnetic properties have been studied to evaluate their strain sensitivity. Films were subjected to a strain by bending of their substrates, which caused a change in the magnetic anisotropy of films via magnetoelastic coupling. Films were exhibited a figure of merit $F=({\Delta}{\mu}/{\mu})/{\varepsilon}$ (change in film permeability $\mu$ per unit strain $\varepsilon$) of $1.2{\times}10^5$, which is comparable with that of amorphous ribbons. To make a study of application of magnetostrictive films as strain sensor elements, we have prepared a micro-patterned film by means of the photolithography and ion milling processes. Impedance change in the patterned films, when strain was applied, was measured over the frequency range from 1 MHz to 1 GHz. Reflecting a large value of figure of merit F, a variation of 46% impedance of films was shown at 100 MHz frequency when a strain of $300{\times}10^{-6}$ was applied.

• Korean Journal of Environmental Agriculture
• /
• v.34 no.4
• /
• pp.309-317
• /
• 2015

BACKGROUND: An analytical method was developed using GC-ECD/MS to precisely determine the residue of fipronil, a phenylpyrazole insecticide used to control a wide range of foliar and soil-borne pests.METHOD AND RESULTS: Fipronil residue was extracted with acetone from representative samples of five raw products which comprised hulled rice, soybean, Kimchi cabbage, green pepper, and apple. The extract was diluted with saline water, and fipronil was partitioned into n-hexane/dichloromethane (20/80, v/v) to remove polar co-extractives in the aqueous phase. Florisil column chromatography was additionally employed for final purification of the extract. Fipronil was separated and quantitated by GC-ECD using a DB-17 capillary column. Accuracy of the proposed method was validated by the recovery from crop samples fortified with fipronil at 3 levels per crop in each triplication.CONCLUSION: Mean recoveries ranged from 86.6% to 106.0% in five representative agricultural commodities. The coefficients of variation were less than 10%. Limit of quantitation of fipronil was 0.004 mg/kg as verified by the recovery experiment. A confirmatory technique using GC/MS with selected-ion monitoring was also provided to clearly identify the suspected residue. Therefore, this analytical method was reproducible and sensitive enough to determine the residue of fipronil in agricultural commodities.

• Korean Journal of Food Science and Technology
• /
• v.27 no.1
• /
• pp.86-91
• /
• 1995

In order to expand the utility of alginic acid in the food industry, we have investigated to prepare low viscous alginic acid using a method for degradation of alginic acid with the enzyme system of Vibrio sp. AL-145. The enzyme showed maximum activity at pH 8.0 and $37^{\circ}C$, and was stable in the pH range 7.5 to 8.5 and at temperature up to $30^{\circ}C$, and 0.5M NaCl needed for the enzyme activity. The viscosity of alginic acid decreased with the reaction time courses regardless of alginic acid and enzyme concentration, and 90% of viscosity decreased with 60 min of reaction time, but the changes of reducing sugar not exhibited. The soluble concentration of partially degradated alginic acid(PDA) in water was about 10%(w/v), and adsorption capacity of $Ca^{2+}$ ion increased with increasing the concentration of PDA. The alcohol concentration on precipitation of PDA was higher than Na-alginic acid.

• Korean Journal of Food Science and Technology
• /
• v.22 no.6
• /
• pp.603-610
• /
• 1990

The structural properties of cold water extractable ${\alpha}-D-glucan$ in rice flours obtained by various milling methods were investigated. The blue value, ${\lambda}_{max}$ values of the iodine complex and ${\beta}-amylolysis$ limit of the cold water extractable ${\alpha}-D-glucan$ were in the range of $0.026{\sim}0.030,\;518{\sim}522\;nm$ and $52.7{\sim}59.6%$, respectively, indicating these materials were composed mainly of amylopectin-like polymer. The gel chromatography on Sepharose CL-2B indicated that the cold water extractable ${\alpha}-D-glucan$ had lower molecular weight but wider molecular weight distribution than that of the original rice amylopectin. The Sephadex G-50 gel chromatography showed that the unit chain distribution of cold water extratable ${\alpha}-D-glucan$ after debranching with pullulanase was similar to that of rice amylopectin. And the ion chromatography of the distribution pattern of the chain length below D.P.30 in the debranched ${\alpha}-D-glucan$ indicated only blade-milled flour was similar to the amylopectin, but in the amount of unit chain below D.P.10, all the ${\alpha}-D-glucan$ in rice flours was higher than that of amylopectin.

• Journal of Radiation Protection and Research
• /
• v.20 no.2
• /
• pp.79-83
• /
• 1995

A number of investigators have reported formation of radiolytic ultrafine particles produced by the interaction of ionizing radiation with atmospheric trace gases. Previous studies have suggested that a very high localized concentration of the hydroxyl radical produced by the radiolysis of water can react with atmospheric trace gases such as $SO_2$ and produce lower vapor pressure compounds that can subsequently nucleate. To determine the trace gas and water vapor concentration dependence of the active, positively charged, first decayt product of radon (Po-218), a well-controlled radon chamber was used in this research. The mobility spectrum of the decay products in the range of $0.07-5.0cm^2/V\;sec$ from the radon chamber was measured using alpha track detector installed inside a specially-designed electrostatic spectrometer. Measurements were taken for different concentrations (0.5ppm to 5ppm) of $SO_2$ in Purified, Compressed air. A kinetics Study following the clustering of $SO_2$ around the $PoO_x^+$ ion in an excess of $SO_2$ for interpretation of the reaction processes was performed.

• Microbiology and Biotechnology Letters
• /
• v.38 no.1
• /
• pp.84-92
• /
• 2010

Antibacterial compound from Bacillus subtilis MJP1 was purified using C18 Sep-Pak cartridge, ion exchange chromatography, and gel filtration chromatography. The purified antibacterial compound showed antibacterial activity against Listeria monocytogenes, Bacillus subtilis, Staphylococcus aureus subsp. aureus, and Enterococcus faecalis. The purified antibacterial compound was found to be stable at $100^{\circ}C$ for 5 min and in the pH range of 3.0~9.0, but it was unstable at pH 10.0. It was inactivated by proteinase K and pronase E, and heat treatment at $121^{\circ}C$ for 15 min, but it was stable with lipase and $\alpha$-amylase treatment, which indicated its proteineous nature. Ultra performance liquid chromatography and electrospray ionization tandem mass spectrometry analysis were used to identify the purified antibacterial compound and confirmed the existence of two peptides (3356.54 Da, 3400.5244 Da).