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Application of the HPLC-DAD/MS Detection for the Quantification of Green Tea Catechins
Young-Hak Kim,Su-Jin Lee,Young-Sun Hwang,Kwang-Hee Yoon,Sung-In Lee,Mi-Young Nam,Lee-Seul Song,Seung-Beom Hong,Min-Suk Lee,Myoung-Gun Choung 한국작물학회 2010 한국작물학회 학술발표대회 논문집 Vol.2010 No.04
Recent interest in green tea polyphenols has increased owing to their antioxidant activities and their possible role in the prevention of cancer and cardiovascular diseases. Typically, 93% compounds of total polyphenols in green tea leaves, many of which are called catechins, are flavonoids. The major tea catechins are a mixture of epicatechin isomers, including (-)-epigallocatechin gallate (EGCG), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epicatechin (EC). Separation of green tea catechins is generally carried out by HPLC-UVD. UV detector is a suitable detector for quantification this class of molecules and allows high sensitivity level for polyunsaturated species. However, UV detection does not discriminate different compounds having similar chromophore groups. More detailed structural information can be collected when a mass spectrometer is coupled with a UV-DAD. MSD is a powerful tool for qualitative analysis to identify and confirm molecular structures of unknown compounds, and it is particularly useful for quantitative analysis, owing to its high sensitivity and selectivity. This study describes the application of HPLC-DAD/MS methods for the rapid and routine analysis of 9 catechins in green tea leaves. Green tea extracts were injected directly onto a reversed phase HPLC column. Compounds, identified on the basis of their absorbance and MS spectrum, included gallic acid, (-)-epicatechin, and their various gallate derivatives. HPLC/MS detection was found to be more sensitive than UV-DAD, and MSD showed good precisions for quantification of catechins.
HPLC-UVD/MS를 이용한 농산물 중 bentazone의 분석법 확립
김영학(Young-Hak Kim),이수진(Su-Jin Lee),송이슬(Lee-Seul Song),황영선(Young-Sun Hwang),이영득(Young Deuk Lee),정명근(Myoung-Gun Choung) 한국농약과학회 2011 농약과학회지 Vol.15 No.2
Bentazone is benzothiadiazole group herbicide, and used to foliage treatment. This herbicide have already been widely used for cereals and vegetables planting in worldwide. This experiment was conducted to establish a determination method for bentazone residue in crops using HPLC-UVD/MS. Bentazone residue was extracted with acetone (adjusted pH 1 with phosphoric acid) from representative samples of five raw products which comprised hulled rice, soybean, apple, green pepper, and Chinese cabbage. The extract was diluted with saline water, and dichloromethane partition was followed to recover bentazone from the aqueous phase. Florisil column chromatography was additionally employed for final clean up of the extract. The bentazone was quantitated by HPLC with UVD, using a YMC ODS AM 303 (4.6 × 250 ㎜) column. The crops were fortified with bentazone at 3 levels per crop. Mean recovery ratio were ranged from 82.0% for a 0.2 ㎎/㎏ in apple to 97.9% for a 0.02 ㎎/㎏ in Chinese cabbage. The coefficients of variation were ranged from 0.5% for a 0.02 ㎎/㎏ in soybean to 9.7% for a 0.02 ㎎/㎏ in Chinese cabbage. Quantitative limit of bentazone was 0.02 ㎎/㎏ in representative five crop samples. A LC/MS with selected-ion monitoring was also provided to confirm the suspected residue. Therefore, this analytical method was reproducible and sensitive enough to determine the residue of bentazone ill agricultural commodities.
Non-destructive Screening of Genetically Modified Soybean Using Near Infrared Spectroscopy
Myoung-Gun Choung,Young-Sun Hwang,Hyeon-Jin Lee,Su-San-Na Choi,Su-Jin Lee,Sung-Taeg Kang,Won-Young Han,In-Youl Baek,Keum-Yong Park 한국작물학회 2008 한국작물학회 학술발표대회 논문집 Vol.2008 No.10
NIR spectroscopy combined with multivariate analysis after the appropriate spectral data pre-treatment has been proved to be a very powerful tool for judgment of the relative pattern of the objects that have very similar properties. In this study, 500 GMO soybean seeds and, 500 non-GMO ones were measured in NIR reflectance mode. Principal component analysis (PCA), and discriminant analysis (DA) were applied to classify soybean with different genes into two groups (GMO and non-GMO). Calibrations were developed using DA regression with the cross-validation technique. The results show that differences between GMO and non-GMO soybeans do exist and excellent classification can be obtained after optimizing spectral pre-treatment. The raw spectra with DA model after the second derivative pre-treatment had the best satisfactory calibration and prediction abilities, with 97% accuracy. The results in the present study show NIR spectroscopy together with chemometrics techniques could be used to differentiate GMO soybean, which offers the benefit of avoiding time-consuming, costly and laborious chemical and sensory analysis.
LC/MS를 이용한 농산물 중 Nitenpyram의 잔류분석
정명근 ( Myoung-gun Choung ),김명현 ( Myunghyun Kim ),안경근 ( Kyung-geun Ahn ),김기쁨 ( Gi-ppeum Kim ),주하은 ( Haeun Joo ),강련웅 ( Ryeon-woong Kang ),황영선 ( Young-sun Hwang ),이영득 ( Young Deuk Lee ) 한국환경농학회 2016 한국환경농학회 학술대회집 Vol.2016 No.-
Nitenpyram is a neonicotinoid insecticide used in agriculture and veterinary medicine to kill external parasites of pets. This experiment was conducted to establish a determination method for nitenpyram residues in crops using LC/MS. Nitenpyram residue was extracted with acetone from representative samples of five raw products which comprised mandarin, green pepper, potato, hulled rice and soybean. The extract was evaporated and dissolved in saturated saline solution. And then the extract was washed by n-hexane partition and recovered by dichloromethane partition. The extract was finally purified by optimized Silica gel column chromatography. On an octadecylsilyl column in LC/MS, nitenpyram was successfully separated from co-extractives of sample, and sensitively quantitated by matrix-matched calibration method using selected ion monitoring(SIM) of 271.1 ion with no interference. Accuracy and precision of the proposed method was validated by the recovery experiment on every crop samples fortified with nitenpyram at 3 concentration levels per crop in each triplication. Mean recoveries ranged from 80.1 to 100.1% in five representative agricultural commodities. The coefficients of variation were all less than 10%, irrespective of sample types and fortification levels. Limit of quantitation(LOQ) of nitenpyram was 0.004 mg/kg as verified by the recovery experiment. This method using LC/MS with selected-ion monitoring technique was clearly identify the suspected residue.
HPLC-UVD/MS를 이용한 농산물 중 Oxycarboxin의 잔류분석
정명근 ( Myoung-gun Choung ),주하은 ( Haeun Joo ),권희주 ( Heeju Kwon ),정주영 ( Juyoung Jeong ),김기쁨 ( Gi-ppeum Kim ),황영선 ( Young-sun Hwang ),이영득 ( Young Deuk Lee ) 한국환경농학회 2017 한국환경농학회 학술대회집 Vol.2017 No.-
Oxycarboxin(5,6-dihydro-2-methyl-N-phenyl-1,4-oxathiin-3-carboxamide-4,4-dioxide) as oxanthiin fungicide is a systemic fungicide commonly used as a seed treatment to control various fungi that cause seed and seeding diseases in agronomic and horticultural crops. An analytical method was developed using HPLC-UVD/MS to precisely determine the residue of oxycarboxin. The oxycarboxin residue was extracted with acetone from representative samples of five raw products which comprised hulled rice, soybean, Kimchi cabbage, green pepper, and apple. The extract was diluted with saline water, and dichloromethane partition was followed to recover oxycarboxin from the aqueous phase. Florisil column chromatography was additionally employed for final purification of the extract. Oxycarboxin was separated and quantitated by HPLC with UVD using a Zorbax SB-AQ C<sub>18</sub> column. Accuracy of the proposed method was validated by the recovery from crop samples fortified with oxycarboxin at 3 levels per crop in each triplication. Mean recoveries ranged from 78.3% to 96.1% in five representative agricultural commodities. The coefficients of variation were less than 10%. Limit of quantitation of oxycarboxin was 0.04 mg/kg as verified by the recovery experiment. A confirmatory technique using LC/MS with selected-ion monitoring was also provided to clearly identify the suspected residue. Therefore, this analytical method was reproducible and sensitive enough to determine the residue of oxycarboxin in agricultural commodities.
축산물 중 유기인계 농약Acephate, Methamidophos 및 Monocrotophos의 잔류분석법 개발
정명근 ( Myoung-gun Choung ),주하은 ( Haeun Joo ),권희주 ( Heeju Kwon ),정주영 ( Juyoung Jeong ),김기쁨 ( Gi-ppeum Kim ),황영선 ( Young-sun Hwang ),이영득 ( Young Deuk Lee ),김정한 ( Jeong Han Kim ) 한국환경농학회 2017 한국환경농학회 학술대회집 Vol.2017 No.-
This experiment was conducted to establish a simultaneous analytical method for 3 kinds organophosphorus pesticide in livestock products using GC-NPD/MS. All the pesticides residues were extracted with acetonitrile and/or acetone from representative samples of five livestock products which comprised beef, pork, chicken, egg and milk. The proteins in milk and egg were dispersed adding sodium oxalate, also the extract was removed non-polar co-extractives and lipids by n-hexane partition. The extract was finally purified by optimized Florisil column chromatography and NH2 cartridge. The analytes were separated and quantitated by GLC with NPD using a DB-17 capillary column. Accuracy and precision of the proposed method was validated by the recovery experiment from 5 kinds livestock product samples fortified with acephate, methamidophos and monocrotophos at 3 concentration levels in each triplication. Mean recoveries ranged from 71.9 to 113.2% in every fortification levels and compounds. The coefficients of variation were all less than 10%, irrespective of fortification levels. Limit of quantitation(LOQ) of the all analytes were 0.005 mg/kg as verified by the recovery experiment. A confirmatory technique using GC/MS with selected-ion monitoring was also provided to clearly identify the suspected residues. Therefore, this analytical method was reproducible and sensitive enough to determine the residues of acephate, methamidophos and monocrotophos in livestock products.
GC-NPD/MS를 이용한 우유 중 유기인계 농약 Acephate, Methamidophos 및 Monocrotophos의 동시분석법 개발
정명근 ( Myoung-gun Choung ),김명현 ( Myunghyun Kim ),안경근 ( Kyung-geun Ahn ),김기쁨 ( Gi-ppeum Kim ),주하은 ( Haeun Joo ),강련웅 ( Ryeon-woong Kang ),황영선 ( Young-sun Hwang ),이영득 ( Young Deuk Lee ) 한국환경농학회 2016 한국환경농학회 학술대회집 Vol.2016 No.-
This experiment was conducted to establish a simultaneous analytical method for 3 kinds organophosphorus pesticide in milk using GC-NPD/MS. All the pesticides residues were extracted with acetonitrile from milk. The phosphoproteins as casein in milk were dispersed adding sodium oxalate, also the extract was removed non-polar co-extractives and lipids by n-hexane partition. The extract was finally purified by optimized Florisil column chromatography and NH2 cartridge. The analytes were separated and quantitated by GLC with NPD using a DB-17 capillary column. Accuracy and precision of the proposed method was validated by the recovery experiment on milk sample fortified with acephate, methamidophos and monocrotophos at 3 concentration levels in each triplication. Mean recoveries ranged from 82.2 to 107.8% in every fortification levels and compounds. The coefficients of variation were all less than 10%, irrespective of fortification levels. Limit of quantitation(LOQ) of the all analytes were 0.005 mg/kg as verified by the recovery experiment. A confirmatory technique using GC/MS with selected-ion monitoring was also provided to clearly identify the suspected residues. Therefore, this analytical method was reproducible and sensitive enough to determine the residues of acephate, methamidophos and monocrotophos in milk.
시설재배 엇갈이배추 중 살균제 Mandipropamid의 수확시기별 잔류 특성
정명근(Myoung-Gun Choung),안경근(Kyung-Geun Ahn),김기쁨(Gi-Ppeum Kim),황영선(Young-Sun Hwang),권찬혁(Chan-Hyeok Kwon),강인규(In-Kyu Kang),이영득(Young Deuk Lee) 한국원예학회 2016 원예과학기술지 Vol.34 No.4
Supervised residue trials for mandipropamid in Korean cabbage(Brassica campestris L.) were conducted to establish its pre-harvest residue limit (PHRL), a criterion to ensure the safety of the terminal pesticide residue during cabbage production. Tissues of Korean cabbage were collected at 0, 1, 3, 5, 7, and 10 days after mandipropamid application and subjected to residue analysis. The analytical method was validated by recoveries ranging from 88.2- 92.2% at two levels (0.4 and 2.0 mg·kg<SUP>-1</SUP>), and a limit of quantitation (LOQ) of 0.04 mg·kg<SUP>-1</SUP>. Mandipropamid residues in Korean cabbage gradually decreased over time. The dissipation rate of the residue would be affected by intrinsic degradation of the compound along with dilution resulting from the fast growth of Korean cabbage. The decay pattern was well fitted by simple first-order kinetics. Biological half-lives of mandipropamid in Korean cabbage ranged from 3.9-4.0 days in two field conditions. Calculated by the regression curve of mandipropamid dissipation, the PHRLs of mandipropamid in Korean cabbage were recommended as 11.07-12.19 and 5.76-6.05 mg·kg<SUP>-1</SUP> for 10 and 5 days prior to harvest, respectively.
사과, 감귤, 고추 및 배추에서 생장조절제 Forchlorfenuron의 HPLC-DAD/MS 분석법 확립
정명근(Myoung-Gun Choung),이진욱(Jinwook Lee),이영득(Young Deuk Lee),황영선(Young-Sun Hwang),강인규(In-Kyu Kang) 한국원예학회 2017 원예과학기술지 Vol.35 No.5
Forchlorfenuron is a plant growth regulator that is currently utilized to accelerate cell division and cell expansion, and promote organ formation and protein synthesis in plants. This experiment was conducted to establish a method for determining forchlorfenuron residues in fruits and vegetables using HPLC-DAD/MS. Forchlorfenuron residue was extracted with acetone from apple, mandarin, green pepper, and kimchi cabbage. The extract was diluted with a large volume of saline water and directly partitioned into dichloromethane to remove the polar co-extractives in the aqueous phase. The extract was purified by optimized Florisil column chromatography. Forchlorfenuron was successfully separated from co-extractives on an octadecylsilyl column in HPLC and quantified by ultraviolet absorption at 265nm with no interference. The accuracy and precision of the proposed method was validated by a recovery experiment of each sample fortified with forchlorfenuron at 3 concentrations per sample in triplicate. Mean recoveries ranged from 75.2 to 94.4% in the four samples. The coefficients of variation were all less than 10%, irrespective of sample type and fortification levels. The limit of quantification of forchlorfenuron was 0.02mg·kg<SUP>-1 </SUP>as verified by the recovery experiment. A method using LC/MS with a selected-ion monitoring technique was also conducted to confirm the identity of the suspected residue. This method is useful for routine analysis of forchlorfenuron residues in apple, mandarin, green pepper, and kimchi cabbage.