• Fisheries and Aquatic Sciences
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• v.19 no.1
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• pp.3.1-3.6
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• 2016

Phlorotannins are reported to have diverse biological properties. However, no analytical methods for the standardization of phlorotannin preparations have been reported. Herein, we developed and validated an analytical method for the determination of dieckol in phlorotannin extracts (PRT) using high-performance liquid chromatography (HPLC). The optimum HPLC conditions consisted of a Supelco Discovery C18 column stationary phase, a mobile phase (A: 15 % HPLC grade methanol in deionized water, B: methanol), UV detection at 230 nm, and a flow rate of 0.7 mL/min. The optimized chromatographic conditions were validated and exhibited good specificity and linearity ($R^2$ > 0.9994-1.0000). The recoveries were in the range of 100.9-102.3 %. The method had good intermediate (%RSD 1.2) and intra-day (%RSD 0.4-1.7) assay precisions. This HPLC method had good accuracy and quality in the determination of dieckol in PRT.

• Journal of the Korean Chemical Society
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• v.35 no.5
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• pp.560-568
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• 1991

The simultaneous determination method which simply determined regulated pesticides was investigated. Sample was extracted with acetone-methanol and partitioned with methylene chloride after addition of saturated NaCl solution. Entract was purified by Bio-Beads S-X3 column using cyclohexane-methylene chloride (1 : 1) as eluate. The determination of pesticides was performed by BP-1 capillary column gas chromatography using ECD and NPD. The average recoveries of pesticides in rice and soy fbean were over 83% and 81%, respectively. It was possible to detect pesticides in rice up to 0.002 ppm by $\alpha-BHC$ and up to 0.05 ppm by carbaryl and in soy bean up to 0.01 ppm by ${\alpha}$-BHC and up to 0.3 ppm by carbaryl.

• Journal of the Korean Society of Tobacco Science
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• v.31 no.1
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• pp.45-50
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• 2009

In this study, a simple gradient RRLC method for rapid determination of carbonyl compounds of cigarette smoke was developed. Within 10 min, 8 carbonyl compounds have been separated and identified on ZORBAX Eclipse XDB-C18 column ($4.6{\times}50\;mm$, $1.8\;{\mu}m$) with gradient elution using water and acetonitrile as a mobile phase. RRLC was used for the quantification of carbonyl compounds in mainstream smoke of 3R4F reference cigarette, and evaluated those efficiencies in the recovery, repeatability and reproducibility. The correlation coefficients ($r^2$) for calibration curves of carbonyl compounds were over 0.9998. The developed RRLC method was successfully applied to the analysis of smoke samples and the recoveries of carbonyl compounds were in the range of 97.5~102.1% with RSD<3.1%.

• Korean Journal of Pharmacognosy
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• v.32 no.3 s.126
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• pp.200-211
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• 2001

This study was carried out to determine the 11 organochlorine, 7 organophosphorus residual pesticides in 251 crude drugs. These residual pesticides in herbal drugs were extracted with acetonitrile and the extracts were cleaned up via LC-florisil solid phase extraction column. The prepared samples were assayed for pesticide residues using GC-ECD, NPD with capillary column and identified by GC-MSD. Recoveries were $63.9{\sim}111.5%$ in the organochlorine pesticides and $69.8{\sim}92.4%$ in the organophosphorus pesticides, and detection limits were $0.001{\sim}0.65\;ppm$ in the organochlorine pesticides and $0.0009{\sim}0.0074\;ppm$ in the organophosphorus pesticides. Pesticide residues were detected in 9 cases.

• Natural Product Sciences
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• v.18 no.2
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• pp.83-88
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• 2012

In order to facilitate the quality control of the fruits of Crataegus pinnatifida, a simple, accurate and reliable HPLC method was developed for the simultaneous determination of the three bioactive compounds: chlorogenic acid (1), rutin (2), and hyperin (3), which were selected as the chemical markers of C. pinnatifida. Separation was achieved on an Agilent Eclipse XDB-C18 column with a gradient solvent system of 0.1% trifluoroacetic acid aqueous-acetonitrile at a flow-rate of 1.0 mL/min and detected at 254nm. All three calibration curves showed good linearity ($R^2$ > 0.998). The recoveries of three marker compounds were in the range of 94.87~111.52 %. The contents of chlorogenic acid (1), rutin (2), and hyperin (3) of the fruits of C. pinnatifida collected from 23 district markets in Korea, Japan, and China were 0.16~0.65 mg/g, 0.07~1.24 mg/g, and 0.03~0.62 mg/g, respectively. The results demonstrated that this method is simple and reliable for the quality control of the fruits of C. pinnatifida.

• Natural Product Sciences
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• v.21 no.3
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• pp.192-195
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• 2015

An antibacterial benzoquinone, 2,6-dimethoxy-1,4-benzoquinone, isolated from Ficus foveolata stems was used as a standard marker for establishment of quantitative HPLC analysis for the stem extracts of F. foveolata. The method utilized a TSK-gel ODS-80Ts column (5 μm, 4.6 × 250 mm) with the mixture of methanol and 5% acetic acid in water (24:76, v/v) as the mobile phase at a flow rate of 1 mL/min, and quantitative detection at 289 nm. The parameters i.e. linearity, intraday and interday precision, accuracy, specificity and sensitivity of the method were evaluated for method validation. The recoveries of the method were 99.5 - 103.6% and good linearity (R² ≥ 0.9999) was obtained. A high degree of specificity, sensitivity as well as repeatability and reproducibility (RSD less than 2 and 5%, respectively) were also achieved. Chloroform was served as the most suitable solvent for extraction of 2,6-dimethoxy-1,4-benzoquinone. The optimised sample preparation and HPLC method can be practically used in the routine quality control process of F. foveolata stem extracts.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.413-417
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• 2003

The last few decades have seen drastic growth in the use of brominated flame retardants(BFRs). There is the problems of polybrominated dibenzo-p-dioxins(PBDDS) and polybrominated dibenzofurans(PBDFs) generation as by-products in combustion process of BFRs. PBDDs/PBDFs are highlighted the new pollutants of environmental contamination, recently. In this study, the 10 kinds of PBDDs/PBDFs standards were used to perform the experiments of recoveries. The analysis of PBDDs/PBDFs in soil environmental samples. was carried out. In silica gel column cleanup, PBDDs/PBDFs eluted until 80mL of n-hexane, and the recovery was obtained 73∼105%. In multi-layer silica gel column cleanup, the recovery was obtained 56∼125% with various elution solvents. In alumina clean process, the standard mixture(PBDES, PBDDs/PBDFs) eluted the first fraction of 2% dichloromethane with n-hexane in the range of 0∼100mL, PBDEs compounds eluted in the second fraction of 50% dichloromethane with n-hexane. In activated carbon column cleanup, the PBBEs eluted to the first fraction(n-hexane) and second fraction(toluene), but PBDDs/PBDFs only eluted to the second fraction. The analytical methods of PBDDs/PBDFs for soil was established based on the experimental results of the environmental samples.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.196-200
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• 2003

A gas chromatography/mass spectrometric assay method was developed for the simultaneous determination of ethylene glycol monomethyl ether (EGME) and diethylene glycol monomethyl ether (DEGME) in spilled aviation fuels. Ethylene glycol monobutyl ether (EGBE) and ethylene glycol monoethyl ether (EGEE) were used as internal standard and surrogate, respectively. The sample preparation consists of back-extraction with 7 mL of methylene chloride after extraction of 50 mL of fuel with 2 mL of water. The extract was concentrated to dryness and dissolved with 100L of methanol and analyzed by CC-MS (SIM). The peaks had good chromatographic properties by using semi-polar column and the extraction of these compounds from fuel also gave high recoveries of 75 and 85 % with small variations for EGME and DEGME, respectively. Method detection limits were 1.3 ng/mL for EGME and 1.0 ng/mL for DEGME in spilled fuel. The method may be useful for fuel-type differentiation between kerosene and JP-8, which may originate from the storage tank.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1998.11a
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• pp.123-123
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• 1998

A number of uracil derivatives have been developed as anti-AIDS drugs having a mechanism of inhibiting cellular reverse transcriptase. A simple and rapid assay technique for recently synthesized KR-V analogues was developed using a high-performance liquid chromatography, and oral pharmacokinetics was examined for assessing their oral bioavailabilites. Plasma samples were analyzed by reversed-phase HPLC using an ODS column with an ultraviolet detection system. All the analogues were eluted within 12 min and the LOQ was 15-30 ng/$m\ell$. The extraction recoveries were higher than 85%, except KR-V1039, 1068 and 1720 having ester group. This chromatic method was well applied to the kinetic studies for KR-V analogues. Among 16 analogues tested in the present work, the 6 compounds including KR-V1123, 1122, 1784, 1783, 1736 and 1700 were found to be bioavailable for oral administration to rats.

• Korean Journal of Veterinary Service
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• v.38 no.4
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• pp.259-264
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• 2015

We investigated the residues of 6 cephalosporins (cefquinome, cephalexin, cephalonium, cefazolin, ceftiofur, cefuroxime) using LC-MS/MS in raw meat in Seoul. This method involves extraction of the residue from the meat by distilled water and methanol followed by a manual of residue analysis published by the National Institute of Food and Drug Safety Evaluation. The recoveries ranged between 74.71~90.01% in beef, 73.37~101.40% in pork and 70.87~95.53% in chicken, respectively. The limits of detection were 0.0004~0.0563 mg/kg, and the limits of quantification were 0.001~0.169 mg/kg respectively. Residues of cephalosporins which exceeded maximum residue limits (MRL) were not exceed in any of the 287 samples. However, it is necessary to develop multi-method, which includes the active metabolites of ceftiofur.