• 대한화학회지
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• 제45권2호
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• pp.149-155
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• 2001

남조류독소, 마이크로시스틴을 초임계유체추출을 이용하여 추출하는 새로운 분석법이 개발되었다. 이 연구에서 사용된 마이크로시스틴들은 초임계 유체 CO$_2$에는 거의 녹지 않지만 90% CO$_2$, 9.0% 메탄올, 1.0% 물로 된 혼합유체를 사용한 결과 성공적으로 추출할 수 있었다. 이 연구에서 사용된 초임계 유체 추출법은 고체상추출법보다 많은 장점들을 가지고 있다. 우선 시료처리단계가 줄어들고, 시료의 손실이 적으며, 분석시간을 단축시킬 수 있다는 장점들이 있다. 또한 전처리 단계가 생략된다는 장점도 있다. ODS 카트리지를 사용하는 고체상 추출법에서 ODS 카트리지가 마이크로시스턴에 대한 흡착력이 떨어지기 때문에 좀 더 극성이 있는 CN 카트리지에 주입시켰다. CN 카트리지는 물 5mL, 0.5 M 아세트산 5mL, 5% 아세트니트릴 5mL로 빗은 후 70% 아세트니릴로 최종용리시킨 후 HPLC로 분리하였다. CN 카트리지를 사용하였을 때 ODS 카트리지보다 더 좋은 회수율과 크로마토그램을 보여주었다.

• 한국콘텐츠학회논문지
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• 제9권11호
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• pp.262-270
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• 2009

세로토닌 수용체 5-$HT_{1A}$에 대한 방사성추적자로 알려진 $^{18}F$-mefway를 개선된 방법으로 합성하고, 소 동물 뇌 microPET 연구를 통해서 이 수용체에 선택적으로 결합하는 지를 확인하려고 한다. 기존 합성 방법을 수정하여 전구체를 합성하고, $[^{18}F]^-$과 $130^{\circ}C$에서 30분간 교반하여 $^{18}F$-mefway를 합성하여, Solid phase extraction(SPE)과 HPLC를 이용해 정제한 다음, 소동물 뇌의 microPET 다이나믹 영상을 얻었다. Oxalyl chloride와 LAH/diethyl ether을 사용해서 기존 합성수율 9%에서 34%로 $^{18}F$-mefway 전구체를 향상된 수율로 합성할 수 있는 개선된 방법을 확립하였다. 이렇게 합성된 $^{18}F$-mefway는 세로토닌 5-$HT_{1A}$수용체 영상용 방사성 의약품으로서 신경정신질환 연구에 이용될 수 있을 것으로 사료된다.

• 한국식품과학회지
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• 제41권2호
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• pp.157-161
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• 2009

원두커피의 PAHs 분석을 위한 시료 전처리는 Soxhlet 추출법과 액/액 추출법 두 가지로 하였다. 두 방법의 간단한 모식도는 Fig. 2을 통해 나타내었다. Soxhlet 추출법을 이용하여 추출한 후 비누화시켜 SPE cartridge로 silica cartridge를 사용하여 효과적으로 정제하였으며, 액/액 추출법은 먼저 비누화를 시킨 후 n-hexane을 이용하여 추출하고 florisil cartridge로 clean up 시킨 후 각각 HPLC-FLD를 사용하여 분석하였다. 이러한 두 가지 방법으로 진행된 실험의 결과 90% 이상의 회수율을 보인 것은 액/액 추출법의 B[a]A, Chrys이었고, 80% 이상의 회수율을 보인 것은 액/액 추출법의 B[b]F, B[k]F, B[a]P, DB[a,h]A과 Soxhlet 추출법의 B[a]A, Chrys으로 나타났으며, 그 외에는 약 70% 정도의 회수율을 나타내었다. 7종의 총 PAHs 회수율은 각각 Soxhlet 추출법은 74.25%이고 액/액 추출법 77.08%로 많은 차이를 보이진 않았지만 액/액 추출법이 더 높은 회수율을 나타내었다. 두 방법 모두에서 Chrys의 회수율이 가장 높았으며, 두 가지 방법을 비교하여 실험한 결과 많은 차이를 보이지는 않았지만 Soxhlet 추출법보다 액/액 추출법이 전처리에 소비되는 시간을 줄일 수 있었으며 또한 액/액 추출법에서 표준물질의 회수율도 높게 나타났다.

• 한국환경농학회지
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• 제31권1호
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• pp.45-51
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• 2012

본 연구는 단감 재배 중 사용되는 살균제인 pyrimethanil과 trifloxystrobin의 생산단계 잔류허용기준 설정을 통하여 안전한 단감 생산에 기여하고자 수행되었다. 먼저 pyrimethanil과 trifloxystrobin을 살포하고, 살포 후 0, 1, 2, 3, 5, 7, 10, 12, 15, 18일에 단감 시료를 채취하여 각각의 농약을 분석하고 생물학적 반감기를 산출한 다음 생산단계 잔류허용기준(PHRL; Pre-Harvest Residue Limit)을 설정하였다. 단감 중 pyrimethanil과 trifloxystrobin은 Acetonitrile을 이용하여 추출하고 $NH_2$ cartridge와 PSA를 이용하여 정제하여 HPLC/DAD를 이용하여 분석하였다. 두 농약에서 검출한계는 모두 0.01 mg/kg이었다. Pyrimethanil의 회수율은 0.1과 0.5 mg/kg 두 수준에서 각각 $81{\pm}1.62%$, $98{\pm}1.58%$ 이었으며, trifloxystrobin의 회수율은 0.1과 0.5 mg/kg 두 수준에서 각각 $91{\pm}2.94%$, $98{\pm}1.25%$이었다. 단감에서 pyrimethanil의 생물학적 반감기는 기준량 살포 시 15.6일, 배량 살포 시 11.6일이었고, trifloxystrobin의 생물학적 반감기는 기준량 살포 시 10.4일, 배량 살포 시 10.3일이었다. 잔류회귀 감소식을 이용한 생산단계 잔류허용기준은 pyrimethanil과 trifloxystrobin은 각각 수확 10일 전 2.69 mg/kg과 0.83 mg/kg으로 제안하였다.

• 한국토양비료학회지
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• 제45권1호
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• pp.43-50
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• 2012

Two typical animal waste management practices, composting and stockpiling, were evaluated for their effect on the degradation of three veterinary antibiotics (VAs), chlortetracycline (CTC), tylosin (TYL), and monensin (MNS). The VAs were applied to horse manure plots subject to composting or stockpiling, and core samples were collected over a period of time. Selected buffer solutions were used to extract the VAs and analysis for concentration was conducted with solid phase extraction (SPE) followed by high performance liquid chromatography tandem mass spectrometry (HPLC/MS/MS) technique. The VAs demonstrated rapid dissipation within ten days followed by a gradual decrease in concentration until the end of the experimental period (141 days). All three VAs degraded more rapidly in the composting samples than in the stockpiling samples, particularly between 20 and 60 days of the observation period. Degradation of the three VAs generally followed a first-order kinetic model, and a fitted model with a calculated rate constant was determined for each treatment. TYL in composting showed the fastest degradation, with a calculated rate constant of $0.91day^{-1}$; the slowest degradation was exhibited by MNS in stockpiling, with rate constant of $0.17day^{-1}$. Calculated correlation coefficients ranged from 0.89 to 0.96, indicating a strong correlation between measured concentrations and fitted values in this study. Although concentration of TYL in composting treatment showed below detection limit during the test period, this study suggests that composting can reduce animal waste contaminants prior to field application as fertilizer.

• 한국자기공명학회논문지
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• 제19권2호
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• pp.67-73
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• 2015

The microcystin is a cyclic heptapeptide from metabolites of cyanobacteria in the genera mycrocystis, anabaeba as a result of eutrophication. It has been known that microcystin-LR is a potent inhibitor of the catalytic subunits of protein phosphatase-1 (PP-1) as well as powerful tumor promoter. The active site of microcystin actually has two metal ions $Fe^{2+}/Zn^{2+}$ close to the nucleophilic portion of PP-1-microcystin complex. We report the isolation and purification of this microcystin-LR from cyanobacteria (blue-green algae) obtained from Daechung Dam in Chung-cheong Do, Korea. Microcystin-LR was extracted from solid-phase extraction (SPE) sample preparation using a CN cartridge. The cyanobacteria extract was purified to obtain microcystin-LR by HPLC method and identified by LC/MS. The detail structural studies that can elucidate the possible role of monovalent and divalent metal ions in PP-1-microcystin complexation were carried out by utilizing molecular dynamics. Conformational changes in metal binding for ligands were monitored by molecular dynamic computation and potential of mean force (PMF) using the method of the free energy perturbation. The microcystin-metal binding PMF simulation results exhibit that microcystin can have very stable binding free energy of -10.95 kcal/mol by adopting the $Mg^{2+}$ ion at broad geometrical distribution of $0.5{\sim}4.5{\AA}$, and show that the $K^+$ ion can form a stable metal complex rather than other monovalent alkali metal ions.

• 한국토양비료학회지
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• 제45권6호
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• pp.867-876
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• 2012

The concentration of veterinary antibiotics in aqueous and sediment matrices was measured in agricultural irrigation ditches bordering several animal-feeding operations (AFOs) and then compared to its concentration in the watershed. Analytical determination in aqueous samples was based on solid phase extraction (SPE) and appropriate buffer solutions were used to extract residuals in sediment samples. Separation and detection of extracted veterinary antibiotics were performed with high performance liquid chromatograph tandem mass spectrometry (HPLC/MS/MS). In general, higher concentrations of antibiotic were observed in the aqueous phase of irrigation ditches, with the highest concentration of erythromycin hydrochloride (ETM-$H_2O$) of $0.53{\mu}g\;L^{-1}$, than in aqueous watershed samples. In contrast, higher concentrations were measured in river sediment than in irrigation ditch sediment with the highest concentration of oxytetracycline of $110.9{\mu}g\;kg^{-1}$. There was a high calculated correlation ( > 0.95) between precipitation and measured concentration in aqueous samples from the irrigation ditches for five of the ten targeted veterinary antibiotics, indicating that surface runoff could be an important transport mechanism of veterinary antibiotics from field to environment. Further, environmental loading calculation based on measured concentrations in aqueous samples and flow information clearly showed that irrigation ditches were 18 times greater than river. This result suggests the likelihood that veterinary antibiotics can be transported via irrigation ditches to the watershed. The transport via surface runoff and likely environmental loading via irrigation ditches examined in this study helps identify the pathway of veterinary antibiotics residuals in the environment.

• 한국환경농학회지
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• 제32권2호
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• pp.128-135
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• 2013

BACKGROUND: This study was performed to develop a single residue analytical method for new herbicide metazosulfuron in crops. METHODS AND RESULTS: Brown rice, apple, mandarin, Kimchi cabbage and soybean were selected as representative crops, and clean-up system, partition solvent and extraction solvent were optimized. Instrumental limit of quantitation (ILOQ), linearity of calibration curve and method limit of quantitation (MLOQ) were determined based on the chromatography and whole procedures. For recovery tests, brown rice, apple, mandarin, Kimchi cabbage and soybean samples were macerated and fortified with metazosulfuron standard solution at three levels (MLOQ, 10 MLOQ and 100 MLOQ). And then those were extracted with acetonitrile, concentrated, and partitioned with ethyl acetate. Then the extracts were concentrated again and cleaned-up through $NH_2$ (aminopropyl) SPE cartridge with acetone : dichloromethane (1% acetic acid) (20 : 80, v/v) before concentration and analysis with HPLC. CONCLUSION(S): ILOQ of metazosulfuron was 2 ng (S/N${\geq}$10) and good linearity was achieved between 0.05 and 12.5 mg/Kg of metazosulfuron standard solutions, with coefficients of determination of 0.9999. MLOQ was 0.02 mg/Kg. Good recoveries from 74.1 to 116.9% with coefficients of variation (C.V.) of less than 10% were obtained, regardless of sample type, which satisfies the criteria of Korea Food and Drug Administration (KFDA). Those results were reconfirmed with LC-MS (SIM). The method established in this study is simple, economic and efficient to be applied to most of crops as an official and general method for residue analysis of metazosulfuron.

• 한국물환경학회지
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• 제25권5호
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• pp.720-726
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• 2009

We investigated the most effective pre-treatment processes and LC/MS/MS condition for microcystins analysis. With a step-by-step pre-treatment, efficiencies of several established methods were compared. At the level of cell burst, sonication method was found to be the most efficient. As a mycrocystins first extraction solvent, 5% acetic acid showed the highest efficiency. An isolation and recovery rate of mycrocystins of ODS Sep-Pak $C_{18}$ cartridge was higher than HLB SPE cartridge. As a final elution solvent from cartridge, 100% MeOH had a better efficiency than others. Using a LC/MS/MS, effective analytical methods were established. C18 reverse column was used and gradient elution was performed with using acetonitrile, 0.1% formic acid as a mobile phase. We analysed to 0.8 mL/min flow rate fit to the $5{\mu}m$ particle size column and $55^{\circ}C$ housing temperature. The validity of established analytical method was evaluated that MDL as average $0.050{\pm}0.014{\mu}g/L$ and LOQ as average $0.160{\pm}0.045{\mu}g/L$ had a good sensitivity over 40 magnification rather than $2{\mu}g/L$ detection limit of HPLC.

• 한국환경농학회지
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• 제33권2호
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• pp.69-77
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• 2014

BACKGROUND: The purpose of this study was to investigate the effects of clothianidin on the soil in terms of clothianidin dissipation and degradation to evaluate its safety in order to provide an analytical foundation for clothianidin and the 5 metabolites related to it. METHODS AND RESULTS: High-performance liquid chromatography(HPLC) was used to separate clothianidin and its metabolites in this study. In soil, after suppressing dissociation-proned ions with weak alkalic $NH_4OH$ and extracting the metabolites with methanol, clothianidin, Methylaminoimidazole(MAI), Methylnitroguanidine(MNG), Thiazolylmethylurea(TZMU) and Thiazolylnitroguanidine(TZNG). Thiazolylmethylguanidine(TMG) were extracted with the addition of neutral $NH_4OAC$ to increasing the intensity of ions. Compounding elements were separated by using Hydrometrix ($ChemElut^{TM}$) and ion-exchanging Solid-phase extraction(SPE) Strong cation-exchanger(SCX) and C18 were used. The recovery rates of clothianidin and 5 metabolites in soil and water ranged from 87.4% to 104.3%. A standard deviation of our analysis for the soil and water samples were less than 5%. CONCLUSION: Well accepted detection limits for clothianidin and 5 metabolites in soil samples based on a dissipation analysis is 0.005 mg/kg and 0.001 mg/L in water samples. The dissipation concentration of this study was decided to be enough to evaluate the dissipation levels of clothianidin and its metabolites.