• Korean Journal of Fisheries and Aquatic Sciences
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• 제34권4호
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• pp.291-298
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• 2001

Seawater, sediment and biota in the Kwangyang Bay were analyzed by gas chromatography/quartz furnace atomic absorption spectroscopy (GC-QFAAS) to investigate concentrations and distribution pattern of butyltin compounds (TBT, DBT, MBT) during February, April and July, 1996, Marine biota analyzed were Tapes japcnicus and Crassostrea gigas. The concentrations of tributyltin (TBT) in seawater were in the range of ND-15.7 ng/L for the surface and ND-68.5 ng/L for the bottom. The highest concentration of TBT in seawater was detected in April for the both, surface and bottom water. The maximum value of $TBT_{(bottom)}/TBT_{(surface)}$, 3.6 in April showed the increased input of TBT from the surface water in April compared to February (2.1) and July (0.9). The concentrations of TBT in the sediment were in the range of ND-8.5 ng/g dry wt. The highest concentration of TBT in the sediment was measured in July, This result seems to attributed to the removal of TBT from water column via sorption onto particulate matters to the relatively undisturbed underlying sediment and increased input of TBT by increased fluxes of detritus of marine plankton after spring bloom, in July. The mean values of partitioning coefficient ($K_d$) of TBT between seawater and sediment were $3.0\times10^3$(February), $7.4\times10^3$(April) and $9.4\times10^3$(July). The concentrations of TBT in biosamples were in the range of ND-93.30 ng/g dru wt. (T. japonicus) and ND-138.53 ng/g dry wt. (C. gigas). The seasonal variation of TBT contents in biota was remarkable. The $K_d$ (biological concentration factor) was $7-41\times10^3$ for T. japonicus. and $5-34\times10^3$ for C. gigas. The measured TBT concentrations in seawater in the study area was sufficient to cause the imposex of shellfish and to retard the growth of aquatic organisms including oyster upon chronic exposure.

• Journal of Food Hygiene and Safety
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• 제26권1호
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• pp.16-24
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• 2011

A method was established for the simultaneous determination of sugar alcohols, erythritol, xylitol, sorbitol, inositol, mannitol, maltitiol, lactitol and isomalt by High Performance Liquid Chromatography (HPLC). The sugar alcohols were converted into strong ultraviolet (UV)-absorbing derivatives with p-nitrobenzoyl chloride (PNBC). HPLC was performed on Imtakt Unison US-$C_18$ column, using acetonitrile: water (77:23) as a mobile phase and UV detection (260 nm). The calibration curves for all sugar alcohols tested were linear in the 10~200 mg/L range. The average recoveries of the sugar alcohols from three confectioneries spiked at 100 ppm of eight sugar alcohol standards ranged from 81.2 to 123.1% with relative standard deviations ranging fromo 0.2 to 4.9%. The limits of detection (LODs) were $0.5{\sim}8\;{\mu}g/L$ and the limits of quantification (LOQs) were $2{\sim}17\;{\mu}g/L$. Reproducibility of 8 sugar alcohols was 0.28~1.97 %RSD. The results of the analysis of confectioneries showed that 89 samples of 130 were detected and the sugar alcohols content of samples investigated varied between 0.4 and 693.7 g/kg. A method for the simultaneous determination of eight sugar alcohols will be used as basic data for control of sugar alcohols in confectioneries, and quality control in food manufacturing.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• 제2권2호
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• pp.92-100
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• 1997

Distribution of bacterial abundance and production was investigated during October, 1995-August, 1996 in Lake Shiwha constructed artificially in 1994. Its water column was distinguished by two layers: the brackish surface layer with salinity ranged from 6 to 20‰ and the saline hypoxic/anoxic bottom layer with salinity of 17 to 27‰ Except for samples collected in March, 1996 (on average 13 ${\mu}g\;l^{-1}$), chlorophyll a concentration ranged from 27.6 to 249.5 ${\mu}g\;l^{-1}$ in the euphotic zone, indicating the hypertrophic condition of Lake Shiwha during most of the studied period. In this study, bacterial productions measured by $^3H$-thymidine incorporation method were similar to those by $^{14}C$-leucine incorporation method. In hypertrophic, surface waters of Lake Shiwha, bacterial abundance and production ranged from 1.4 to $19.5{\times}10^9\;cells\;l^{-1}$ and from 1.6 to $126.5{\times}10^7\;cells\;l^{-1}\;h^{-1}$ respectively; 2 to 4 fold and 2 to 30 fold higher than those in eutrophic coastal waters outside of Lake Shiwha, respectively. Turnover times of bacterial community in the surface layer of Lake Shiwha ranged from 0.2 to 8.9 day, indicating that bacteria in the lake seemed to adapt to the hypertrophic condition. In the hypoxic bottom layer, bacterial abundance and production was up to 3 fold and 20 fold lower than those in the surface layer, and showed slow bacterial growth. Significant correlations between the bacterial abundance, production, and community turnover time with water temperature indicate water temperature was the important factor controlling distribution and growth of bacteria. However, during summer season, bacterial production seemed to be regulated by supply of substrates.

• Journal of the Korean Society of Marine Environment & Safety
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• 제25권4호
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• pp.457-467
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• 2019

To investigate the long-term variation characteristics of nutrients in the east coast of Korea, water temperature, salinity, dissolved oxygen, and nutrients were measured at three stations of Sokcho, Jukbyeon and Gampo coasts for five years from 2013 to 2017. For five years, the water temperature of the East Sea coast was in the range of $1.2{\sim}28.8^{\circ}C$, the salinity was in the range of 30.63~34.79 and the dissolved oxygen (DO) was in the range of 3.53~7.64 mL/L. Distribution and variation of the water environment factors in the study area were determined by the vertical stratification of water column and distribution of water temperature. The high DO concentration in Sokcho coast From 2015 to August 2016 is presumed to be the result of the southward inflow of North Korean Cold Water (NKCW). Concentrations of dissolved inorganic nitrogen (DIN, $NH_4-N+NO_2-N+NO_3-N$) ranged $0.11{\sim}24.19{\mu}M$, phosphate concentration ranged $0.01{\sim}1.75{\mu}M$, and silicate ranged $0.17{\sim}32.80{\mu}M$. The N:P ratio was in the range of 0.7~54.3 (mean 15.2) and the N:P slope was in the range of 11.67~13.75. The N:P ratios in this study were lower than the Redfield ratio (16), indicating that nitrate did act as a limiting factor in phytoplankton growth. The correlation ($R^2$) of total N:P ratio was as high as 0.95, indicating that the effect of the surrounding land or non-point sources was not significant. In conclusion, the spatial and temporal variation of nutrients in the east coast of Korea was determined by the vertical mixing of water mass with thermocline and mainly affected by physical factors such as influx of external water masses and coastal upwelling, and the influences from inflows from the land were minimal.

• Radiation Oncology Journal
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• 제19권1호
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• pp.66-73
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• 2001

Purpose : For the research of Boron Neutron Capture Therapy (BNCT), fast neutrons generated from the MC-50 cyclotron with maximum energy of 34.4 MeV in Korea Cancer Center Hospital were moderated by 70 cm paraffin and then the dose characteristics were investigated. Using these results, we hope to establish the protocol about dose measurement of epi-thermal neutron, to make a basis of dose characteristic of epi-thermal neutron emitted from nuclear reactor, and to find feasibility about accelerator-based BNCT. Method and Materials : For measuring the absorbed dose and dose distribution of fast neutron beams, we used Unidos 10005 (PTW, Germany) electrometer and IC-17 (Far West, USA), IC-18, ElC-1 ion chambers manufactured by A-150 plastic and used IC-l7M ion chamber manufactured by magnesium for gamma dose. There chambers were flushed with tissue equivalent gas and argon gas and then the flow rate was S co per minute. Using Monte Carlo N-Particle (MCNP) code, transport program in mixed field with neutron, photon, electron, two dimensional dose and energy fluence distribution was calculated and there results were compared with measured results. Results : The absorbed dose of fast neutron beams was $6.47\times10^{-3}$ cGy per 1 MU at the 4 cm depth of the water phantom, which is assumed to be effective depth for BNCT. The magnitude of gamma contamination intermingled with fast neutron beams was $65.2{\pm}0.9\%$ at the same depth. In the dose distribution according to the depth of water, the neutron dose decreased linearly and the gamma dose decreased exponentially as the depth was deepened. The factor expressed energy level, $D_{20}/D_{10}$, of the total dose was 0.718. Conclusion : Through the direct measurement using the two ion chambers, which is made different wall materials, and computer calculation of isodose distribution using MCNP simulation method, we have found the dose characteristics of low fluence fast neutron beams. If the power supply and the target material, which generate high voltage and current, will be developed and gamma contamination was reduced by lead or bismuth, we think, it may be possible to accelerator-based BNCT.

• Korean Journal of Food Science and Technology
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• 제31권4호
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• pp.945-951
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• 1999

A simple and practical method for the determination of gardenia yellow in foods was developed. In this method, analysis of gardenia yellow in food products has been carried out by the detection of crocetin and/or geniposide as indicator compounds. As a new analytical method for gardenia yellow, we adopted crocetin, which is produced from colored components of gardenia yellow by alkaline hydrolysis, as an indicator compound. The analysis of gardenia yellow was performed by reverse phase high performance liquid chromatography using a Capcell pak $C_{18}$ column at wave length 240 nm (geniposide) and 435 nm (crocetin). The recovery rates of geniposide and crocetin were found to be 93.4% and 87.8% for Dan Mu Ji, 90.2% and 85.9% for milk, 92.8% and 86.5% for snack, respectively. With this method, the range of crocetin and geniposide contents $({\mu}g/g)$ were as follows: $ND{\sim}1.7$ and $ND{\sim}14.1$ for Dan Mu Ji, $ND{\sim}0.2$ and $ND{\sim}13.6$ for milk, $ND{\sim}1.6$ and $ND{\sim}0.9$ for snack, respectively. The detection limits of crocetin and geniposide were 0.07 ${\mu}g/g$ and 0.05 ${\mu}g/g$, respectively.

• Korean Journal of Food Science and Technology
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• 제45권6호
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• pp.693-699
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• 2013

A simple, sensitive, and specific method for quantifying the nicotine content of synthetic favoring substances (SFS) was developed using high performance liquid chromatography (HPLC) with a photo-diode array detector (PDA). Nicotine was extracted from SFS samples by using an acid-base liquid-liquid extraction method with dichloromethane and distilled water. The nicotine content was quantified by HPLC/PDA (261.9 nm) with a $C_{18}$ column under a gradient of 10% acetonitrile with 20 mM ammonium formate (ammonia solution adjusted to pH 8.7) to 100% acetonitrile. The calibration curve, analyzed from concentration standards between 0.1 to 2 mg/L, presented linearity with a correlation coefficient ($r^2$)>0.9999. The limit of quantitation (LOQ) of nicotine in SFS was 0.4 mg/kg, and the average recoveries ranged from 76.4% to 96.3%. The repeatability of measurements, expressed as the coefficient of variation (CV%), ranged from 1.74 to 5.12%. This newly developed method for nicotine quantification in SFS can be considered an analytical method with an acceptable level of sensitivity and repeatability.

• Journal of Food Hygiene and Safety
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• 제29권2호
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• pp.131-140
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• 2014

The objective of this study was to develop a simultaneous method of 8 penicillin antibiotics including amoxicillin, ampicillin, cloxacillin, dicloxacillin, nafcillin, oxacillin, penicillin G and penicillin V in meat using LC-MS/MS. The procedure involves solid phase extraction with HLB cartridge and subsequent analysis by LC-MS/MS. To optimize MS analytical condition of 8 compounds, each parameter was established by multiple reaction monitoring in positive ion mode. The chromatographic separation was achieved on a $C_{18}$ column with a mobile phase of 0.05% formic acid and 0.05% formic acid in acetonitrile at a flow rate of 0.2 mL/min for 20 min with a gradient elution. The developed method was validated for specificity, linearity, accuracy and precision in beef, pork and chicken. The recoveries were 71.0~106%, and relative standard deviations (RSD) were 4.0~11.2%. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.003~0.008 mg/kg and 0.01~0.03 mg/kg, respectively, that are below maximum residue limit (MRL) of the penicillins. This study also performed survey of residual penicillin antibiotics for 193 samples of beef, pork and chicken collected from 9 cities in Korea. Penicillins were not found in all the samples except a sample of pork which contained cloxacillin (concentration of 0.08 mg/kg) below the MRL (0.3 mg/kg).

• Journal of Pharmacopuncture
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• 제17권4호
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• pp.36-49
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• 2014

Objectives: Quercetin and curcuminoids are important bioactive compounds found in many herbs. Previously reported high performance liquid chromatography ultraviolet (HPLC-UV) methods for the detection of quercetin and curcuminoids have several disadvantages, including unsatisfactory separation times and lack of validation according the standard guidelines of the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use. Methods: A rapid, specific, reversed phase, HPLC-UV method with an isocratic elution of acetonitrile and 2% v/v acetic acid (40% : 60% v/v) (pH 2.6) at a flow rate of 1.3 mL/minutes, a column temperature of $35^{\circ}C$, and ultraviolet (UV) detection at 370 nm was developed. The method was validated and applied to the quantification of different types of market available Chinese medicine extracts, pills and tablets. Results: The method allowed simultaneous determination of quercetin, bisdemethoxycurcumin, demethoxycurcumin and curcumin in the concentration ranges of $0.00488-200{\mu}g/mL$, $0.625-320{\mu}g/mL$, $0.07813-320{\mu}g/mL$ and $0.03906-320{\mu}g/mL$, respectively. The limits of detection and quantification, respectively, were 0.00488 and $0.03906{\mu}g/mL$ for quercetin, 0.62500 and $2.50000{\mu}g/mL$ for bisdemethoxycurcumin, 0.07813 and $0.31250{\mu}g/mL$ for demethoxycurcumin, and 0.03906 and $0.07813{\mu}g/mL$ for curcumin. The percent relative intra day standard deviation (% RSD) values were $0.432-0.806{\mu}g/mL$, $0.576-0.723{\mu}g/mL$, $0.635-0.752{\mu}g/mL$ and $0.655-0.732{\mu}g/mL$ for quercetin, bisdemethoxycurcumin, demethoxycurcumin and curcumin, respectively, and those for intra day precision were $0.323-0.968{\mu}g/mL$, $0.805-0.854{\mu}g/mL$, $0.078-0.844{\mu}g/mL$ and $0.275-0.829{\mu}g/mL$, respectively. The intra day accuracies were 99.589%-100.821%, 98.588%-101.084%, 9.289%-100.88%, and 98.292%-101.022% for quercetin, bisdemethoxycurcumin, demethoxycurcumin and curcumin, respectively, and the inter day accuracy were 99.665%-103.06%, 97.669%-103.513%, 99.569%-103.617%, and 97.929%-103.606%, respectively. Conclusion: The method was found to be simple, accurate and precise and is recommended for routine quality control analysis of commercial Chinese medicine products containing the flour flavonoids as their principle components in the extracts.

• Korean Journal of Medicinal Crop Science
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• 제8권1호
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• pp.1-8
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• 2000

Achillea sibirica Ledeb. is widely distributed in Korea and has been often used as folk medicine in peptic and tonic. As one of our searches for bioactive (anti oxidation) compounds from medicinal plants, we studied Achillea sibirica Ledeb. (Compositae). Antioxidant activity of Achillea sibirica was determined by measuring lipid peroxide produced when a mouse liver homogenate was exposed at $90^{\circ}C$ using 2-thiobarbituric acid (TBA) and by evaluation the radical scavenging activity on 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical. Whole parts of Achillea sibirica was extracted with methanol and its extracts was fractionated with organic solvent; n-Hexane, methylene chloride, ethyl acetate, n-Butanol. EtOAc fraction exhibited antioxidant activity and From its, two flavonoid glycosides were isolated by silica gel and gel filtration colume chromatography and identified to kampferol 3-O-glucoside and luteolin 7-O-neo-hesperidoside, respectively, by physico-chemical and spectroscopical method. At antioxidant activity test for two compounds isolated, antioxidant activity was showed too. And from hexane fraction sterol was is isolated and identificated to mixture of campesterol, stigmasterol, and ${\beta}-sitosterol$.