• Korean Journal of Environmental Agriculture
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• v.37 no.2
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• pp.117-124
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• 2018

BACKGROUND: Oxycarboxin(5,6-dihydro-2-methyl-N-phenyl-1,4-oxathiin-3-carboxamide-4,4-dioxide) as oxanthiin is a systemic fungicide commonly used for control of various pathogens in agronomic and horticultural crops. In an effort to develop an analytical method to trace the fungicide, a method using HPLC equipped with UVD/MS was studied. METHODS AND RESULTS: Oxycarboxin was extracted with acetone from hulled rice, soybean, Kimchi cabbage, green pepper, and apple samples. The extract was diluted with saline water, followed by liquid-liquid extraction with methylene chloride. Florisil column chromatography was employed for the purification of the extracts. Oxycarboxin was determined on a Zorbax SB-AQ $C_{18}$ column by HPLC with UVD. Accuracy of the proposed method was validated by the recovery tests from crop samples fortified with oxycarboxin at 3 levels per crop. CONCLUSION: Mean recoveries ranged from 78.3% to 96.1% in five representative agricultural commodities. The coefficients of variation were less than 10%, and limit of quantitation of oxycarboxin was 0.04 mg/kg. A confirmatory technique using LC/MS with selected-ion monitoring was also provided to clearly identify the suspected residue. The method was reproducible and sensitive to determine the residue of oxycarboxin in agricultural commodities.

• Journal of Applied Biological Chemistry
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• v.52 no.3
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• pp.109-115
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• 2009

The gene encoding a putative aspartate aminotransferase in Xanthomonas oryzae pv. oryzae (Xoo) was cloned using PCR technique. The gene was ligated with pET-21(a) vector containing His6 tag and expressed in E. coli BL21(DE3). Affinity purification of the recombinant aspartate aminotransferase with Ni-NTA resin resulted in one band by SDS-PAGE analysis. The purified enzyme showed a molecular weight of 43 kDa, as expected. The enzyme was the most active toward L-aspartate as an amino donor, indicating that the purified enzyme is one of aspartate aminotrans-ferases exist in Xoo. Optimal activity of the enzyme was observed at around pH 7.5 and stability was much higher at alkaline pH rather than acidic pH values. The enzyme was considerably activated by the presence of manganese ion, showing about 157% of control activity at 1.0 mM.

• Journal of Microbiology and Biotechnology
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• v.4 no.2
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• pp.113-118
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• 1994

A bacterial strain NS-83 isolated from soil was able to produce an extracellular thermostable protease. The strain was identified as Pseudomonas aeruginosa based on its morphological and physiological characteristics. A thermostable protease from this strain has been purified to homogeneity as judged by SDS-PAGE and isoelectric focusing. The purification procedures included hydrophobic interaction, ion exchange, and gel filtration chromatography. The $M_r$ and the pl of the enzyme were 32,000 and 5.9, respectively. The optimal pH at 55$^{\circ}C$ and the optimal temperature at pH 7.0 were 8.0 and 60$^{\circ}C$, respectively. The D-values of the enzyme at 60, 65, and 70$^{\circ}C$ were 22, 2.1, and 0.75 hrs, respectively. The enzyme activity was significantly inhibited in the presence of 1 mM o-phenanthroline or EDTA, suggesting that the enzyme is metalloprotease. The $K_m$, and $V_{max}$ for Hammarsten casein were found to be 3.2 mg/ml and 0.918 unit/ml, respectively. These enzymatic properties were similar to those of elastase produced from P. aeruginosa IFO 3455, but the enzyme was clearly different from the reported elastase, in respect to $Ca^{++}$ effects on enzyme-thermostability. This property, together with amino acid composition analysis, confirmed that the enzyme differs from the known P. aeruginosa elastase.

• Journal of Nutrition and Health
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• v.31 no.8
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• pp.1315-1323
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• 1998

Effect of oral taurine supplementation on plasma total and phospholidpid -fatty acid profiles and their metabolism were evaluated in healthy female adults. Among twenty five female volunteers(23.6$\pm$0.3 years old ) participated in the taruine supplementation program(6g taurine /day), twenty four subjects succesfully completed the 2 week program , and only nine subjects continued to take taurine for another 2 weeks. Levels of plasma fatty acids and taruine were measured by gas-liquid chromatobraphy and an automated amino acid analyzer based on ion exchange chromatography, respectively. Plasma taurine concentration s of the subjects were 108. 7$\pm$3.4 , 184.2$\pm$8.2 and 235.9$\pm$77.0$\mu$emol/L at 0 , 2 and 4 weeks of taurine supplementation. Fatty acid compositions and elongation and desaturation indices of polyunsaturated fatty acids (PUFA) in plasma total lipids were not influenced by oral taurine supplementation. However, fatty acid compositions and their metabolism in plasma phospholipids were significantly affected by taurine supplementation in female adults. Compared to the values for 0 week, the percentage of saturated fatty acids (SFA) in plasma phospholipid was significantly lowered at 2 weeks, but elevated at 4 weeks of taurine supplementation. In contrast , the percentage of phospholipid PUFA significantly increased at 2 weeks and decreased at 4 weeks of taurine supplementation from to the values for 0 weeks. Foru weeks of oral taurine supplementation signifinatly elevated the eongation index(20 : 4$\omega$6 ⇒22 : 4 $\omega$6, p<0.01), and decreased the desaturation index (20 : 3 $\omega$6 ⇒20 : 4 $\omega$6 , p<0.01) of $\omega$6 fatty acids in plasma phospholipids. Plasma taurine concentration was positively correlated with the percentage of 14 : 0 fatty acids and the enlongation index o f$\omega$3 fatty acids(20 : 5 $\omega$3 ⇒22 : 5 $\omega$3), and thenegatively correlated with the percentage of 20 : 0 in plasma phospholipids. These results indicate that oral taurine supplementation for 4 weeks signidicantly elelvated the percentage of SFA, and lowered the percentage of PUFA in plasma phospholipids with no influence on plasm total fatty aicd composition in healthy female adults.

• Environmental Mutagens and Carcinogens
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• v.21 no.2
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• pp.122-127
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• 2001

4-tert-octylphenol (OP) is a surfactant additive widely used in the manufacture of a variety of detergents and plastic products. Also, OP is known to have estrogenic activity by interacting with development and functions of endocrine system. This study was carried out to obtain toxicokinetic parameters of OP in male Sprague-Dawley rats. Male rats were administered OP, by either single oral (gavage) applications of 50, 100 or 200 mg/kg body weight. or a single intravenous injections of 1, 5 or 10 mg/kg body weight. Blood samples taken at several time intervals after administration were obtained from the femoral artery. Analysis of blood samples for OP was performed by gas chromatography mass spectrometry (GC/MS). The detection limit of OP was 1.9 ng/$m\ell$ at SIM (selected ion monitoring) mode of GC/MS. Calibration curve for analysis of the concentrations of OP in plasma was (OP/butylphenol peak area ratio) = 0.0294 $\times$ (plasma cone.) + 0.028 ($r^2$= 0.9991). The OP plasma concentration was 3921 ng/$m\ell$ immediately after single intravenous application, decreased rapidly within 45 min, and was detectable at low concentration up to 6 hr after application. When administered orally in rats (50, 100 and 200 mg/kg), OP was detected in the blood early after gavage administration, indicating the rapid initial uptake from gastrointestinal tract, with Tmax obtained from 0.67~0.83 hr. Using the AUC (area under the curve) of plasma concentration vs. time, low oral bioavailabilities of 1.2, 5.0 and 5.3% were calculated for the 50, 100 and 200 mg/kg groups, respectively.

• Bulletin of the Korean Chemical Society
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• v.23 no.2
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• pp.225-228
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• 2002

Amorphous $Ga_2O_3$ films have been grown on Si(100) substrates by metal organic chemical vapor deposition (MOCVD) using gallium isopropoxide, $Ga(O^iPr)_3$, as single precursor. Deposition was carried out in the substrate temperature range 400-800 $^{\circ}C$. X-ray photoelectron spectroscopy (XPS) analysis revealed deposition of stoichiometric $Ga_2O_3$ thin films at 500-600 $^{\circ}C$. XPS depth profiling by $Ar^+$ ion sputtering indicated that carbon contamination exists mostly in the surface region with less than 3.5% content in the film. Microscopic images of the films by scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed formation of grains of approximately 20-40 nm in size on the film surfaces. The root-mean-square surface roughness from an AFM image was ${\sim}10{\AA}$. The interfacial layer of the $Ga_2O_3$/Si was measured to be ${\sim}35{\AA}$ thick by cross-sectional transmission electron microscopy (TEM). From the analysis of gaseous products of the CVD reaction by gas chromatography-mass spectrometry (GC-MS), an effort was made to explain the CVD mechanism.

• Analytical Science and Technology
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• v.11 no.2
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• pp.88-91
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• 1998

Bromide($Br^-$) was separated and quantified with $2.8mM-NaHCO_3/2.2mM-Na_2CO_3$ by Ion Chromatography. Bromide was eluted at 8.9 min. and the detectetion limit was 2.5 ng. We compared with bromide concentration in normal or methylbromide intoxicated bloods and tissues. Bromide concentrations were 2.0~5.8 ppm in normal bloods and 1.0~5.3 ppm in normal tissues. In fatal cases of methylbromide intoxication, blood bromide concentrations (4 cases) of 74.2~139 ppm and tissue bromide concentration (1 case) of 76 (heart)~201 (lung) ppm were detected. In fatal cases, blood bromide concentrations. were 12~22 times higher than those of normal bloods.

• Analytical Science and Technology
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• v.7 no.1
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• pp.65-78
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• 1994

The herbicide mixture of 7 triazines and 9 phenoxyalkanoic acid esters was simultaneously separated and determinated with the selected ion monitoring by using gas chromatography/mass spectrometry. The extraction recoveries of those herbicides from the reagent water were studied for the organic solvent extraction(LLE) with methylene chloride. The calibration curves of them showed good linearity over the concentration range of 0.2~0.5ng/ml and the detection limits were 0.2~0.5ng/ml for 100ml of water. This analytical method could be applied to the drinking water and biological sample.

• Journal of Food Hygiene and Safety
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• v.5 no.3
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• pp.159-164
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• 1990

To detect and quantitation residual antibiotics and antibacterial agents in meats, we performed a biological assay employing the three microorganisms Bacillus subtilis ATCC 6633, Micrococcus luteus ATCC 9341, and Bacillus cereus var. mycoides ATCC 11778 for the screening purpose and developed a Gas Chromatography-mass Spectrometry(GC/MS) analysis for the confirmation and quantiation. In the biological assay (paper disk method), three test solution are used depending on the character of the residual antibiotics and antibacterial agents, follow by a simple clean up procedure which includes homogenization with Mcilvaine buffer, defatting with includes homogenization with Mcilvaine buffer, defatting with hexane, extraction with chloroform, clean-up by Sep-Pak $C_{18}$ and Bakerbond SPE carboxylic acid column. The chloroform layer is used for the analysis of sulfa agents. macrolides antibiotics and antibacterial agents, Adsorbed materials in the Sep-Pak $C_{18}$ were also employed for th analysis of penicillins and tetracyclines. Effluents from the Sep-Pak $C_{18}$ were cleaned-up one more by Bakerbond 10 SPE COOH column and employed for the analysis of aminoglycosides. In the instrumental analysis by using the GC/MSD, residual antibiotics and antibacterial agent were quantitated by selected ion monitoring (SIM) mode after derivatization. A simultaneous analysis of six residual antibiotic and antibacterial agent such as oxytetracycline, penicillin, ampicillin, choliraphenicol and thiamphenicol was developed with simple cleanup procedures revealing good recovery and reproducibility. Also, simultaneous detection of macrolides antibiotics such as erythromycin, spiramycin, and oleandomycin was developed after acid hydrolysis due to their large molecular structures. Because of the high reproducibility and selectivity of these two methods, it is very desirable that the combination of the two methods be used in the bioassay for the screening of residual antibiotics and antibacterial agent and that GC/MSD analysis be used for the confirmation and quantitation.

• Korean Journal of Food Science and Technology
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• v.37 no.3
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• pp.360-363
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• 2005

To detect falcarinol in Acanthopanax senticosus, its stem and bark were extracted with methanol fractionated with petroleum ether and diethyl ether, and separated by silica gel column chromatography, Resulting six crude samples were compared with standard falcarinol through TLC on silica gel plates. Fraction 6 showed $R_{f}$ value of 0.46 similar to that of standard falcarinol. Through analytical reverse phase HPLC/PDA, UV spectra of standard falcarinol and traction 6 recorded between 200 and 340 nm showed identical peaks and UV spectra patterns. GC/MS revealed standard falcarinol and fraction 6 have equal retention times of 7.4 and 8.5 min before and after TMS-derivatization, respectively. Standard falcarinol and fraction 6 showed more similar spectrum patterns after TMS-derivatization than before. These results confirm presence of falcarinol in A. senticosus.