• Korean Journal of Environmental Agriculture
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• v.38 no.4
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• pp.321-331
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• 2019

BACKGROUND: Pinoxaden is the phenylpyrazoline herbicide developed by Syngenta Crop Protection, Inc. and marketed on 2006. The maximum residue levels for wheat and barley were set by import tolerance. Thus, Ministry of Food and Drug Safety (MFDS) official analytical method determining Pinoxaden residue was necessary in various food matrixes. Satisfaction of international guideline of CODEX (Codex Alimentarius Commission CAC/GL 40) and National Institute of Food and Drug Safety Evaluation-MFDS (2017) are additional pre-requirements for analytical method. In this study, liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was investigated to analyze residue of Pinoxaden (M4), which is defined as pesticide residue in Korea, in foods. METHODS AND RESULTS: Pinoxaden (M4) was extracted followed by acid digestion (2hr reflux with 1N HCl) and pH adjusting (pH 4-5 with 3% ammonium solution). To remove oil, additional clean-up step with hexane saturated with acetonitrile was required to high oil contained sample before purification. HLB cartridge and nylon syringe filter were used for purification. Then, samples were analyzed by LC-MS/MS using reserve phase column C₁₈. Five agricultural group representative commodities (mandarin, potato, soybean, hulled rice, and red pepper) were used to verify the method in this study. The liner matrix-matched calibration curves were confirmed with coefficient of determination (r²) > 0.99 at calibration range 0.002-0.2 mg/kg. The limits of detection and quantitation were 0.004 and 0.01 mg/kg, respectively, which were suitable to apply Positive List System (PLS). Mean average accuracies of pinoxaden (M4) were shown to be 74.0-105.7%. The precision of pinoxaden and its metabolites were also shown less than 14.5% for all five samples. CONCLUSION: The method investigated in this study was suitable to CODEX (CAC/GL 40) and National Institute of Food and Drug Safety Evaluation-MFDS (2017) guideline for residue analysis. Thus, this method can be useful for determining the residue in various food matrixes in routine analysis.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.42 no.4
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• pp.321-328
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• 2016

In this study, we investigated identification of anti-oxidative constituents from Ficus erecta var. sieboldii King (F. erecta) leaves. DPPH and $ABTS^+$ radical scavenging activities were screened for the ethanol extract and solvent fractions, and ethyl acetate fraction showed the most potent scavenging activities. Five constituents were isolated from the ethyl acetate fraction of F. erecta leaves; monoolein (1), oleic acid (2), lutein (3), afzelechin (4), catechin (5). The chemical structures of the isolated compounds were elucidated based on the spectroscopic data including NMR spectra, as well as comparison of the data to the literature values. As far as we know, all of the compounds 1 ~ 5 were isolated for the first time from this plant. Studies on DPPH and $ABTS^+$ radical scavenging activities were conducted for the isolated compounds. Among them, afzelechin (4) and catechin (5) showed strong DPPH and $ABTS^+$ radical scavenging activities, whose activities were comparable to a positive control vitamin C. Also, the content of catechin isolated from this plant was determined by HPLC and it was about 3.8 mg/g for the 70% ethanol extract and 20.8 mg/g for the ethyl acetate fraction. From these results, F. erecta leaves extract could be potentially applicable as anti-oxidant ingredients in cosmetic industries.

• Korean Journal of Environmental Agriculture
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• v.35 no.3
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• pp.166-174
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• 2016

BACKGROUND: The current study developed a monitoring method of 6 veterinary antibiotics (amoxicillin, ampicillin, enrofloxacin, tetracycline, chlortetracycline, oxytetracycline) in agricultural soils using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in positive electrospray ionization mode.METHODS AND RESULTS: Sample preparation was carried out using acidic acetonitrile and citrate salts followed by purification with dispersive solid phase extraction (d-SPE). Separation on Eclipse Plus C₁₈ column was conducted in gradient of the mobile phase, 0.1% formic acid and 5 mM ammonium formate in methanol (A) and 0.1% formic acid and 5 mM ammonium formate in distilled water (B). The linearity of the matrix-matched calibrations expressed as the coefficient of determination was good with R²≥0.9900. The limit of quantifications (LOQs) ranged from 0.5 to 10 μg/kg for all analytes. Analysis of 51 agricultural soil samples taken in the Republic of Korea revealed concentrations less than 1.9 μg/kg for enrofloxacin, 75.5 μg/kg for chlortetracycline.CONCLUSION: The method was successfully applied to monitor 6 veterinary antibiotics from 51 field incurred agricultural soil samples in 17 provincial areas throughout the Republic of Korea. The developed method was simple, easy, and versatile and can be used for monitoring various veterinary antibiotics in soil.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.spc1
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• pp.110-122
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• 1996

The n-3 family fatty acids containing ${\alpha}$-linolenic acid(18:3, ALA) have been known as physiological activation materials such as inhibitory effects on the incidence of hyper-tension, coronary heart disease and cancers as well as the control of senilc dementia. Although a lot of ALA(about $63\%$) are contained in perilla oil, it has not been commercialized yet because the purification technique of the ALA has not been well established. The procedure of purification of ALA from perilla oil was saponified with 1 N-KOH /ethanol and then saturated and low level unsaturated fatty acids were removed by low-temperature crystallization method. The concentrated unsaturated fatty acids (containing about $75\%$ ALA) went down through the silver nitrate-impregnated silica column chromatography for separation of high purity of ALA. The results obtained we Fraction B, C and D contained ALA more than $85.5\%$(recovery, >$88.9\%,\;95.4\%$(recovery, >$54.4\%$) and $99.9\%$(recovery, >$31.5\%$) in purity, respectively. Seed oil content of the tested varieties were ranged from 34.8 to $54.1\%$ with $45.3\%$ of varietal means. The major omega fatty acids contained in the oil were oleic acid(n-9) $15.2\%$, linoleic acid(n-6) $13.9\%$ and linolenic acid(n-3) $63.1\%$ in the mean value. Varietal variation of n-9, 6 and 3 fatty acids ranged of $9.5\~21.4\%,\;9.1\~20.4\%$ and $50.6\~70.5\%$ respectively. Unsaturated fatty acid were averaged $92.2\%$ of seed oil in fatty acid composition. The ratios of n-6 to n-3 ranged of $0.13\~0.34\%$($0.22\%$ in mean value). The highest n-3 fatty acid variety was Yecheonjong being $70.5\%$. The lowest variety in ratios of n-6 to n-3 was Goseongjong being $0.13\%$. Oil content showed positive correlation with stearic acid and linolenic acid, while the negative correlation with oil content and linoleic acid. On the other hand, A significant negative correlation were showed between linolnic acid and the ratios n-6/n-3 fatty acid, saturated fatty acid. Saturated fatty acid was highly correlated with unsaturated fatty acid negatively being $r= -0.723^{**}$.

• Korean Journal of Food Science and Technology
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• v.43 no.1
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• pp.51-57
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• 2011

From the total methanolic extract of Gardenia jasminoides (Rubiaceae), various antioxidative characteristics were identified in terms of nitrite scavenging ability, 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical cation inhibition, superoxide dismutase (SOD)-like activity, and elongation effect of lipid peroxidation using Rancimat. After successive partitioning with n-hexane, chloroform, n-butanol, and water, potent nitrite scavenging abilities were shown in the n-butanol fraction and water fraction, and $IC_{50}$ values were 183 ppm and 194 ppm, respectively. As for ABTS radical cation inhibition, the chloroform fraction was most potent and its $IC_{50}$ was 159 ppm. SOD-like activity was slightly low in all of the fractions. The elongation effect of lipid peroxidation also increased dose-dependently and the antioxidative index (AI) of the total methanolic extract was 2.93 in 1000 ppm, which was more effective than 1.66 of butylated hydroxy anisol in the same concentration. The compounds I and II were isolated through silica gel column chromatography of the active fractions, and identified as geniposide and crocin, respectively, by $^1H-NMR$ spectral data. The $IC_{50}$ values for the nitrite scavenging abilities of geniposide and crocin were 940 ppm and 77 ppm, respectively. In ABTS radical cation inhibition, the $IC_{50}$ values of geniposide and crocin were 684 ppm and 549 ppm, respectively. And the $EC_{50}$ value for SOD-like activity of crocin was 259 ppm, which was much smaller than 453 ppm by the positive control, chlorogenic acid. The $EC_{50}$ value of geniposide could not be identified.

• Analytical Science and Technology
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• v.9 no.1
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• pp.35-42
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• 1996

A rapid analytical method based on capillary electrophoresis is described for the determination of trace anions in high-purity chemicals which is used to prevent corrosion demage in nuclear power plants. Separations are carried out at 20kV using trimethylsilane-coated fused-silica capillary ($70cm{\times}50$ or $75{\mu}m$ i.d.) with the electrolyte of 5mM Chromate(pH=8). Detection was achieved using on-column indirect photometry at 254nm. The simultaneous analysis of inorganic anions, chloride, nitrate, sulfate, azide and phosphate was performed using methods of hydrodynamic(>1ppm) and / or electrokinetic(<1ppm) injection. The results of studies on the coexisting anions on analyte ions shows that peak responses of analyte in hydrodynamic injection is constant without effect of coexisting anions, but those of analysis in electrokinetic injection is strongly dependant upon the kind of coexisting anions and its ionic mobility. The analyte enrichment rate, hence peak response, is positive relationship with the resistance of the sample solution. Thus, appropriate measures, such as standard addition or internal standard technique, must be used to account for differences in conductance of standard and sample solutions.

• Mass Spectrometry Letters
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• v.5 no.2
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• pp.42-48
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• 2014

A specific and sensitive liquid chromatography-electrospray ionization tandem mass spectrometry method (LC-ESI-MS/MS) was developed and validated for the simultaneous quantification of porphyrins (coproporphyrin, pentacarboxylporphyrin, hexacarboxylporphyrin, heptacarboxylporphyrin, and uroporphyrin) in human plasma and urine. Acidified plasma samples and urine samples were prepared by using liquid-liquid extraction using ethyl acetate and protein precipitation with acetonitrile, respectively. The separation was achieved onto a Synergi Fusion RP column ($150mm{\times}2.0mm$, $4{\mu}m$) with a gradient elution of mobile phase A (0.1% formic acid in 2 mmol/L ammonium acetate, v/v) and mobile phase B (20% methanol in acetonitrile, v/v) at a flow rate of $450{\mu}L$/min. Porphyrins and the internal standard (IS), coproporphyrin I-$^{15}N_4$, were detected by a tandem mass spectrometer equipped with an electrospray ion source operating in positive ion mode. Multiple reaction monitoring (MRM) transitions of the protonated precursor ions and the related product ions were optimized to increase selectivity and sensitivity. The proposed method was validated by assessing selectivity, linearity, limit of quantification (LOQ), precision, accuracy, recovery, and stability. The calibration curves were obtained in the range of 0.1-100 nmol/L and the LOQs were estimated as 0.1 nmol/L for all porphyrins. Results obtained from the validation study of porphyrins showed good accuracy, precision, recovery, and stability. Finally, the proposed method was successfully applied to clinical studies on the autism spectrum disorder (ASD) diagnosis of 203 Korean children.

• Journal of Wetlands Research
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• v.10 no.2
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• pp.81-96
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• 2008

This study was performed to know about the characteristics of geochemicals of sampling sites in Suncheon bay. Salinity and parameters of water pollution as COD, DIN and DIP showed typical character of an estuary with its values higher at the end of estuary and gradually lowering at the up stream. The value of Excess DIN showed positive so the phosphorus appeared in a role as limiting nutrient. As quoted results of correlation analysis of SPSS and PCA, salinity was revealed as a main factor of control for water qualities at sampling sites in Suncheon bay. The Mz of wet lands and intertidal zone in Sun-cheon bay showed a variation of 6.74 to $8.52{\phi}$ and the sorting also to appeared poorly sorted to very poorly sorted. The fractional composition of phosphorus in phosphorus of sediments were high and appeared orderly as redisual-P> NAI-P> apatite-P> absorbed-P. The labile-Phosphorus showed high concentration then the other station. It means that phosphorus of these stations can easily move from the deposit to the water column than another station.

• The Korean Journal of Zoology
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• v.33 no.4
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• pp.435-445
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• 1990

Gonadotropin releasing horrnone (GnRH) is known to be extrahypothalamically localized with a broad range including gonad. It remains, however, unknown whether GnRH is locally synthesized in the gonad. The present srudy aims to identity expression and cellular localization of GnRH-Iike mRNA and immunoreactive GnRH in the rat gonad. GnRH radioimmunoassay and chromatographic extracts on G-50 sephadex column showed that rat gonadal extracts contained a substantial amount of immunoreactive GnRH similar to the hypothalamic and synthetic GnRH. Although a wide distribution of immunostainable GnRH-like molecule with different cell types in the rat ovary was observed, the major cell population hybridized with GnRH probe appears to be granulosa. theca cells and corpus luteum. Immunoreactive GnRH-Iike peptides were distributed m various regions of testis, including spermatogenic cells, Sertoli cells and Leydig cells. In situ hybridization revealed that positive signals of GnRH-Iike mRNA were predominandy present in Sertoli cells within some seminiferous tubules, but absent in the outside of seminiferous tubules in the testis. This study clearly demonstrated that GnRH-Iike molecule present in the rat gonad may be resulted from the local synthetic machinery of GnRH supporting the notion that this peptide may act as autocrine and/or paracrine role in intra-gonadal communication.

• Ocean and Polar Research
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• v.38 no.3
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• pp.195-207
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• 2016

Because the high latitude region in the North Pacific is characterized by high primary production in the surface water enriched with nutrients, it is important to understand the variation of surface water productivity and associated nutrient variability in terms of global carbon cycle. Surface water productivity change or its related nutrient utilization rate during the Northern Hemisphere Glaciation (NHG; ca. 2.73 Ma) has been reported, but little is known about such circumstances under gradual climate cooling since the NHG. Bulk nitrogen isotope (${\delta}^{15}N_{bulk}$) of sedimentary organic matter has been used for the reconstruction of nutrient utilization rate in the surface water. However, sedimentary organic matter experiences diagenesis incessantly during sinking through the water column and after burial within the sediments. Thus, in this study we examine the degree of nitrate utilization rate during the early Pleistocene (2.4-1.25 Ma) since the NHG, using the diatom-bound nitrogen isotope (${\delta}^{15}N_{db}$), which is known to be little influenced by diagenesis, from Site U1343 in the Bering slope area. ${\delta}^{15}N_{db}$ values range from ~0.5 to 5.5‰, which is lower than ${\delta}^{15}N_{bulk}$ values, but they vary with larger amplitude. Variation patterns between ${\delta}^{15}N_{db}$ values and biogenic opal concentration are generally consistent, which indicates that the nitrate utilization rate is closely related to opal productivity change in the surface water. A positive correlation between opal productivity and nitrate utilization rate was observed, which is different from the other high latitude regions in the North Pacific. The main reason for this contrasting relationship is that the primary production in the surface water at Site U1343 is influenced mostly by the degree of sea ice formation. Still, although concerns about diagenetic alteration have been avoided by using ${\delta}^{15}N_{db}$, the effects of the preservation state of biogenic opal and the species-dependent isotopic fractionation on ${\delta}^{15}N_{db}$ should be assessed in the future studies.