• ALGAE
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• v.24 no.1
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• pp.47-55
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• 2009

Recently, interest in plant-derived food additives has developed natural antioxidants, in order to alternate syn-thetic antioxidants with several disadvantages. In the present study, different organic fractions from solvent parti-tions of 80% methanol extract from Jeju benthic diatoms, Achnanthes longipes, Navicula sp. and Amphora coffeaeformis was assessed for their potential antioxidant effects. Among the solvent fractions tested, n-hexane (80.4%) and 80% methanol extract (76.6%) from A. longipes, chloroform (63.2%) from Navicula sp. and n-hexane (67.4%) from A. cof-feaeformis were effective in DPPH free radical scavenging. Fractions of chloroform (53.4%) and n-hexane (53.1%) from A. longipes exhibited higher activities on $H_2O_2$ scavengin. Fraction of n-Hexane from A. longipes exhibited the highest hydroxyl radical scavenging activity and NO. scavenging activity (56.5% and 75.6%, respectively). Aqueous residue from A. coffeaeformis (75.6%) showed the highest metal chelating effect. chloroform and ethyl acetate frac-tion of all the diatoms exhibited significant antioxidant activities in lipid peroxidation inhibitory activity. In particu-lar, both chloroform and the ethyl ecetate fraction from A. longipes and A. coffeaeformis exhibited lipid peroxidation inhibitory activity significantly higher than that of $\alpha$- tocopherol. These data suggest that the Jeju benthic diatoms tested are rich in hydrophilic and hydrophobic antioxidative compounds with different antioxidative properties that can be applied in food industry.

• Food Science of Animal Resources
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• v.44 no.4
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• pp.873-884
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• 2024

Flunixin is a veterinary nonsteroidal anti-inflammatory agent whose residues have been investigated in their original form within tissues such as muscle and liver. However, flunixin remains in milk as a metabolite, and 5-hydroxy flunixin has been used as the primary marker for its surveillance. This study aimed to develop a quantitative method for detecting flunixin and 5-hydroxy flunixin in milk and to strengthen the monitoring system by applying to other livestock and fishery products. Two different methods were compared, and the target compounds were extracted from milk using an organic solvent, purified with C₁₈, concentrated, and reconstituted using a methanol-based solvent. Following filtering, the final sample was analyzed using liquid chromatography-tandem mass spectrometry. Method 1 is environmentally friendly due to the low use of reagents and is based on a multi-residue, multi-class analysis method approved by the Ministry of Food and Drug Safety. The accuracy and precision of both methods were 84.6%-115% and 0.7%-9.3%, respectively. Owing to the low matrix effect in milk and its convenience, Method 1 was evaluated for other matrices (beef, chicken, egg, flatfish, and shrimp) and its recovery and coefficient of variation are sufficient according to the Codex criteria (CAC/GL 71-2009). The limits of detection and quantification were 2-8 and 5-27 ㎍/kg for flunixin and 2-10 and 6-33 ㎍/kg for 5-hydroxy flunixin, respectively. This study can be used as a monitoring method for a positive list system that regulates veterinary drug residues for all livestock and fisheries products.

• Korean Journal of Environmental Agriculture
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• v.36 no.1
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• pp.43-49
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• 2017

BACKGROUND: Greenhouse crops are one of agricultural products consumed largely in Korea. Cucumber is a typical example as main vegetables of greenhouse crops. Thus, pesticide residue analysis is an important requirement to guarantee pesticide safety of cucumber. This work was aim to investigate the residues of penthiopyrad and pyriofenone in cucumber after harvest. METHODS AND RESULTS: Cucumber was subjected to treat with penthiopyrad and pyriofenone at a level of recommended dose 0, 1, 2, 3, 5, 7 and 10 days before harvest under greenhouse conditions. The samples were extracted with organic solvent by using a homogenizer and purified on solid phase cartridge column followed by LC-MS/MS analysis. The recovery levels of penthiopyrad and pyriofenoneranged from approximately 81 to 93% with the method limit of 0.005 mg/kg and coefficient of variation less than 10%. Penthiopyrad and pyriofenone were detected at a level less than maximum residue limit in cucumber at 10 days before. The half-lives of penthiopyrad and pyriofenone were determined to 2.4 ~ 2.6 days. CONCLUSION: Penthiopyrad and pyriofenone are suggested to use in cucumber 10 days before harvest to reach their levels less than maximum residue limit.

• Journal of Convergence for Information Technology
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• v.8 no.5
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• pp.29-36
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• 2018

Ulmus davidiana supercritical fluid residue EtOH extracts(USCFR) and ethyl acetate solvent fraction (USCFREA) of supercritical extraction foil were investigated in order to examine the recycling of supercritical extraction foil in the process of studying Ulmus davidiana branch supercritical extract. Experiments were performed for the determination of total phenol content. The $IC_{50}$ value(ppm) of DPPH radical scavenging activity and ABTS radical scavenging activity was $7.42{\pm}0.09$, $7.50{\pm}0.05$, $22.94{\pm}0.09$, $6.43{\pm}0.10$, and USCFREA, respectively, as compared with the positive control (vitamin C) with values $17.80{\pm}0.14$ and $5.34{\pm}0.06$, respectively. The antioxidative activities of USCFR and USCFREA were confirmed to be superior to the positive control group. In anti-allergic activity studies, both USCFR and USCFREA showed concentration-dependentanti-allergic activity, and USCFREA showed strong anti-allergic activity even at very low concentrations. Thetotal phenolic contents (ugEG, ugGA; ppm) of USCFR were $134.17{\pm}0.13$, $132.02{\pm}0.24$ and USCFREA were $154.77{\pm}1.05$ and $153.18{\pm}1.10$, respectively. Based on the above results and strong antioxidant activity, USCFR and USCFREA hold the potential to be considered as basic research materials for the development of therapeutic supplements based medicines or functional cosmetics related to chronic inflammatory skin immunity diseases.

• The Korean Journal of Pesticide Science
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• v.15 no.1
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• pp.22-27
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• 2011

Nonylphenols are toxic compounds classified as endocrine disruptors. We investigated the nonylphenols clean-up procedures for the contamination control in the quantitative analysis. In this research we analyzed the residual nonylphenols in the solvent and the SPE cartridges. First, at the analysis of HPLC grade solvents (n-hexane, diethyl ether, ethyl acetate and its mixture), diethyl ether was confirmed the residue as 0.963 ${\mu}g/mL$, and we eliminated the contaminant through the distillation with $CaH_2$, Second, at the analysis of SPE cartridges (silica gel and Florisil), all products were showed the residue at 0.046~13.0 ${\mu}g/mL$, but unfortunately the residue in the cartridge were not easily removed with referenced methods in all tested SPE cartridges except in silica gel SPE cartridge with glass ware.

• KSBB Journal
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• v.27 no.4
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• pp.227-231
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• 2012

Whole plants of Zostera asiatica were extracted twice with acetone/methylene chloride (A+M) and methanol (MeOH) in turn. The combined crude extracts were evaporated in vacuo and then the residue was partitioned between water and methylene chloride. The aqueous layer was fractionated into $H_2O$ and n-butanol and then the organic layer was also fractionated into 85% aq. MeOH and n-hexane, successively. The crude extracts and their solvent fractions were evaluated for their inhibitory effect on growth of human cancer cells AGS, HT-29, MCF-7, and HT-1080 cells by MTT reduction assay. Among samples tested, 85% aq. MeOH and n-hexane fractions showed strong cytotoxic effect against AGS, HT-29, and MCF-7 cells. On the other hand, for HT-1080 cell, 85% aq. MeOH fraction exhibited the strongest cytotoxic effect.

• Analytical Science and Technology
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• v.15 no.1
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• pp.67-71
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• 2002

The residual analysis and half-life time of imidazole fungicide prochloraz in soils (silty clay) were investigated by gas chromatography equipped electron capture detector (GC-ECD). The soil samples were extracted acetone/hexane(1:1) solvent and analyzed after separated by $LC-NH_2$ Sep-Pak solid column. Linear sensitivity of standard calibration curve was Y = 268.8600X + 0.0664, $R^2=0.9998$ between 0.05~1.00 ng. The detection limit was 0.02 mg/L and the average recoveries were 94.5~97.3% from the standard additional experiments with 0.10 and 0.40 mg/L. The half-life time was 24.4 days in room laboratory and 7.6 days in the field test soil.

• Journal of Microbiology and Biotechnology
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• v.20 no.2
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• pp.294-300
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• 2010

The Iro protein is a member of the HiPIP family with the [$Fe_4S_4$] cluster for electron transfer. Many reports proposed that the conserved aromatic residues might be responsible for the stability of the iron-sulfur cluster in HiPIP. In this study, Tyr10 was found to be a critical residue for the stability of the [$Fe_4S_4$] cluster, according to site-directed mutagenesis results. Tyr10, Phe26, and Phe48 were essential for the stability of the [$Fe_4S_4$] cluster under acidic condition. Trp44 was not involved in the stability of the [$Fe_4S_4$] cluster. Molecular structure modeling for the mutant Tyr10 proteins revealed that the aromatic group of Tyr10 may form a hydrophobic barrier to protect the [$Fe_4S_4$] cluster from solvent.

• Korean Journal of Veterinary Service
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• v.29 no.3
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• pp.317-330
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• 2006

This study was conducted to develop the analytical method about simultaneous determination for synthetic antimicrobials in muscle by high performance liquid chromatography - mass selective detector (HPLC- MSD). Solid phase extraction (SPE), matrix solid phase dispersion (MSPD) and liquid-liquid extraction (LLE) have been adapted as pretreatment procedures for HPLC- MSD. Among various solvent tested, methanol was chosen for extraction of synthetic antimicrobials in muscles. For the optimized response, the values of various MS parameters including fragment voltage, drying gas flow, nebulizer pressure, drying gas temperature were verified. The average recovery rates using MSPD and SPE for muscles of bovine and pork were 78.9-127.1% and 78.3-121.7%, respectively. This method was verified the satisfactory performance for fourteen synthetic antimicrobials excepting carbadox in muscle of pork as detection limit of $0.05{\mu}g/g$ on API/ES SIM mode.

• Carbon letters
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• v.16 no.3
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• pp.171-182
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• 2015

Mesophase pitch is an important starting material for making a wide spectrum of industrial and advanced carbon products. It is produced by pyrolysis of petroleum residues. In this work, mesophase formation behavior in petroleum residues was studied to prepare environmentally-benign mesophase pitches, and the composition of petroleum residues and its influence on the mesophase formation was investigated. Two petroleum residues, i.e., clarified oil s (CLO-1, CLO-2) obtained from fluid catalytic cracking units of different Indian petroleum refineries, were taken as feed stocks. A third petroleum residue, aromatic extract (AE), was produced by extraction of one of the CLO-1 by using N-methyl pyrrolidone solvent. These petroleum residues were thermally treated at 380℃ to examine their mesophase formation behavior. Mesophase pitches produced as a result of thermal treatment were characterized physico-chemically, as well as by instrumental techniques such as Fourier-transform infrared spectroscopy, nuclear magnetic resonance, X-ray diffraction and thermogravimetry/derivative thermogravimetry. Thermal treatment of these petroleum residues led to formation of a liquid-crystalline phase (mesophase). The mesophase formation behavior in the petroleum residues was analyzed by optical microscopy. Mesophase pitch prepared from CLO-2 exhibited the highest mesophase content (53 vol%) as compared to other mesophase pitches prepared from CLO-1 and AE.