• Journal of Korean Society of Environmental Engineers
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• v.32 no.7
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• pp.690-698
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• 2010

Contamination of groundwater resources by organic chemicals has become an issue of increasing environmental concern. Surfactant-enhanced aquifer remediation (SEAR) is widely recognized as one of the most promising techniques to remediate organic contaminations in-situ. Solutions of surfactant or surfactant with polymer are used to dramatically expedite the process, which in turn, may reduce the treatment time of a site compared to use of water alone. In the design of surfactant-based technologies for remediation of organic contaminated aquifers, it is very important to have a considerable analysis using extensive numerical simulations prior to full-scale implementation. This study investigated the formation and flow of microemulsions during SEAR of organic-contaminated aquifer using the finite difference model UTCHEM, a three-dimensional, multicomponent, multiphase, compositional model. The remediation process variables considered in this study were the sequence of injection fluids, the injection and extraction rate, the concentrations of polymer in surfactant slug and chase water, and the duration of surfactant injection. For each variable, temporal changes in injection and production wells and spatial distributions of relative saturations in the organic phase were compared. Cleanup time and cumulative organic recovery were also quantified. The study would provide useful information to design strategies for the remediation of nonaqueous phase liquid-contaminated aquifers.

• Research in Plant Disease
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• v.15 no.3
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• pp.222-229
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• 2009

A Pseudomonas strain SG3 producing biosurfactant and showing antifungal and insecticidal activities was isolated from agricultural soil severely contaminated with machine oils. The antagonistic bacterium inhibited mycelial growth of all of the tested fungal pathogens. The fermentation broth of SG3 also effectively suppressed the development of various plant diseases including rice blast, tomato gray mold, tomato late blight, wheat leaf rust, barley powdery mildew and red pepper anthracnose. An antifungal substance was isolated from the fermentation broth of SG3 by ethyl acetate partitioning, silica gel column chromatography and preparative HPLC under the guide of bioassay. The chemical structure of the antifungal substance was determined to be rhamnolipid B by mass and NMR spectral analyses. The antifungal biosurfactant showed a potent in vivo antifungal activity against gray mold and late blight on tomato plants. In addition, rhamnolipid B inhibited mycelial growth of B. cinerea causing tomato gray mold and zoospore germination and mycelial growth of P. infestans causing tomato late blight. Pseudomonas sp. SG3 producing rhamnolipid B could be used as a new biocontrol agent for the control of plant diseases occurring on tomato plants.

• Journal of Applied Biological Chemistry
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• v.60 no.4
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• pp.313-319
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• 2017

Strawberries are one of the main commodities in Korea and have been exported over 30 million dollar. And the safety has recently become an important issue in the agro-trade, pesticide residue is most important matter of safe agricultural products. As strawberries can be cultivated using elevated production system, so it is possible to use the drenching. When spraying the pesticides, the use of drenching can be lower amount of residual than using foliar treatment. In this study, time sequential residual amount of pesticides were compared between drenching and foliar application in strawberries. Pesticides were treated with the standard and double dosage and samples were collected at 0, 3, 6, 9, 13, 16 and 21 day and analyzed by LC and LC-MS/MS after liquid-liquid extraction and QuEChERS. Two pesticides were detected less than 1 mg/kg in all samples for drenching treatment. Carbendazim residues in drenching treatment were 5 to 25 times lower than foliar application. And azoxystrobin was not detected in strawberries of drenching treatment.

• Analytical Science and Technology
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• v.18 no.3
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• pp.250-256
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• 2005

A selective method of high performance liquid chromatography with UV detector has been applied to determine 4 tetracycline antibiotics in the animal food, simultaneously. The targets were chlortetracycline (CTC), doxycycline (DC), oxytetracycline (OTC), and tetracycline (TC) that are used routinely in veterinary medicine for prevention and control of disease. Food samples were beef, pork, chicken, milk, whole egg, flatfish (Limanda yokohamae), jacopever (Sebastes hubbsi), seabream (Chrysophrys major), eel (Anguilla japonica) and lobster (Hommarus americanus). After extracting food samples with 20% trichloroacetic acid and McIlvaine buffer, they were purified by a $C_18$ SPE cartridge with 0.01M methanolic oxalic acid solution. The concentrated residue was re-dissolved in methanol, filtered, cleaned up and analyzed on a $C_18$ column. The mobile phase was a mixture of 0.01M oxalic acid and acetonitrile with a gradient ratio from 85:15 to 60:40. The UV wavelength was 365 nm. The overall recoveries were ranged from 71% to 98% and the limit of detections were 0.022 for CTC, 0.012 for DC and OTC and 0.009 mg/kg for TC at signal/noise > 3, respectively. As results, CTC, DC and TC were not detected in all selected food samples, however, OTC was detected in meat and fishes. The determined level of OTC was 0.04 ppm for pork, 0.17 ppm for flatfish and 0.05 and 0.08 ppm for jacopever, that were within the Maximum Residue Limits (MRLs) in the food.

• Analytical Science and Technology
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• v.17 no.6
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• pp.520-526
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• 2004

To determine 6 anti-impotence drug-like compounds such as sildenafil, vardenafil, tadalafil, homosildenafil, hydroxyhomosildenafil and hongdenafil in food, simultaneously, high performance liquid chromatography was applied. In the case of solid sample, it was extracted in organic solvents after homogenizing with mortar and pestle. Whereas liquid sample was just diluted in water and then extracted in organic solvents. Maximum lengths of UV for targets have been identified on photodiode array spectra. As results, vardenafil, hongdenafil, hydroxyhomosildenafil, sildenafil, homosildenafil, and tadalafil were eluted in order using $C_{18}$ column in acetonitrile containing phosphoric acid as the mobile phase. The maximum wavelength (${\lambda}_{max}$) was 216 nm for vardenafil, 233 and 282 nm for hongdenafil, 222 and 293 nm for hydroxyhomosildenafil, sildenafil and homosildenafil, and 284 nm for tadalafil. The overall recoveries were ranged from 95% to 109% and the limit of detection was about 0.04 mg/kg at signal/noise>3. Levels of targets in the selected food samples were 1.7 (hongdenafil) ~ 63 (tadalafil) mg/one dose.

• Analytical Science and Technology
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• v.24 no.1
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• pp.1-9
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• 2011

We described an estimation of measurement uncertainty in quantitative analysis of 11-nor-9-carboxy-${\Delta}^9$-tetrahydrocannabinol (THC-COOH), the metabolite of ${\Delta}^9$-tetrahydrocannabinol, in hair samples by using the bead-assisted liquid-liquid extraction and gas chromatography-tandem mass spectrometric (GC-NCI-MS/MS) detection. Traceability of measurement was established through the use of reference materials, calibrated volumetric tubes, volume measuring devices, and measuring instruments. The analytical results were compared and the different contributions to the uncertainty were evaluated. Inter-day variation was performed by using statistical analysis of several indicative factors. Measurement uncertainty associated with the analyte in real forensic hair samples were estimated using QC data. The major factor of contribution to combined standard uncertainty was inter-day repeatability, while those associated with preparation of analytical standard and also sample of weight were insignificant considering the degree of contribution. Relative uncertainty of relative extended standard uncertainty divided into the measured concentration of the analyte was 17% in a hair sample. The uncertainty of result evaluation will be invaluable to improve quality of the analysis.

• Analytical Science and Technology
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• v.21 no.6
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• pp.459-473
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• 2008

Antifouling agents including tributyltin (TBT) compound and its derivatives have been used for many years, but the usage of TBT in Korea was legally restricted in 2003, due to its significant environmental impact. Following this, many new alternative antifouling agents have been used. In this experiment, four major antifouling agents were selectively analyzed to study their release in seawater and tidal flats on the Korean Peninsula. These new antifouling agents were extracted from the seawater and tidal flats using a liquid-liquid extraction method and microwave extraction, respectively. The measured concentrations of Irgarol 1051, Sea-Nine 211, Dichlofluanid and Chlorothalonil ranged from N.D.$-23.80ng/{\ell}$, N.D.$-15.30ng/{\ell}$, N.D.$-61.69ng/{\ell}$ and N.D.$-4.19ng/{\ell}$ in the seawater samples and from N.D.-159.45 ng/g, N.D.-476.57 ng/g, N.D.-59.79 ng/g and N.D.-21.27 ng/g in the tidal flat samples, respectively. Interestingly, these new antifouling agents were not detected in any area in the tidal flats at Pusan, whereas a certain amount of them was found in the seawater.

• Analytical Science and Technology
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• v.20 no.1
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• pp.84-90
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• 2007

To determine levels of 11 sulfonamides for animals in food, simultaneously, a selective method of high performance liquid chromatography with UV detector has been applied. The targets were sulfachlorpyridazine (SCP), sulfadiazine (SDZ), sulfadimethoxine (SDM), sulfisoxazole (SSX), sulfamerazine (SMZ), sulfamethazine (SMT), sulfamethoxazole (SMX), sulfamethoxypyridazine (SMP), sulfamonomethoxine (SMM), sulfaquinoxaline (SQX) and sulfathiazole (STZ). Food samples were beef, pork, chicken, milk and whole egg that were collected at the main 6 cities in Korea as Seoul, Busan, Daejon, Incheon, Mokpo and Gangneung. After homogenizing food samples with sodium phosphate solution and acetonitrile, it was extracted with n-hexane. The mobile phase gradient was a mixture of 5 mM potassium phosphate (pH 3.25) and methanol with a gradient ratio from 100:0 to 30:70. The UV wavelength was 270 nm. The overall recoveries were ranged from 75% to 95% and the limit of detection was minimum 0.004 mg/kg for SMT, and 0.007 mg/kg for STZ at signal/noise > 3, respectively. As results, sulfonamide drugs were not detected in most of the selected food samples, however, sulfamonomethoxine was detected in meat. The determined level of sulfamonomethoxine were 0.03 and 0.06 mg/kg for beef that were below the MRLs.

• Analytical Science and Technology
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• v.19 no.5
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• pp.441-448
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• 2006

11-nor-9-carboxy-${\Delta}^9$-tetrahydrocannabinol (THCCOOH) is the major metabolite of tetrahydrocannabinol (THC) which is the primary psychoactive component of marijuana. It is also the target analyte for the discrimination marijuana use. A method using solid-phase extraction (SPE) and gas chromatography/mass spectrometry (GC/MS) was developed for the determination of THCCOOH in human urine. Urine samples (3 mL) were extracted by SPE column with a cation exchange cartridge after basic hydrolysis. The eluents were then evaporated, derivatized, and injected into the GC/MS. The limits of detection (LOD) and quantitation (LOQ) were 0.4 and 1.2 ng/mL, respectively. The response was linear with a correlation coefficient of 0.999 within the concentration range of 1.2 (LLE 1.3)~50.0 ng/mL. The precision and accuracy were stable within 1.20% and the recovery was 83.6~90.7%. The recovery of SPE method was lower than that of liquid-liquid extraction (LLE), but there were no apparent differences in LOD, LOQ, precision and accuracy between the two methods. While SPE method is used as a very effective and rapid procedure for sample pretreatment, and clean extracts, LLE method was not suitable for the extraction procedure of THCCOOH in urine. The applicability of the method was proven by analyzing a urine samples from a marijuana abusers.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.10
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• pp.1347-1352
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• 2009

The effects of methanol extract of barely (Hordeum vulgare) on alcohol-induced damages of liver were investigated in male ICR mice. Mice were divided into three groups, control, ethanol, and ethanol plus 0.15% of barley extract. After four weeks of ethanol feeding, ethanol group significantly increased the P450 content, CYP2E1 and CYP1A2 enzyme activities, whereas ethanol plus barely group markedly decreased to levels similar to control group. Catalase activity in ethanol group was significantly lower than that in control group; however, ethanol plus barely group stimulated catalase activity as well as SOD activity significantly. These results indicated that barely extract modulated P450 enzymes for ethanol-induced liver damage and might be useful in developing functional food for alcoholic liver damage.