Young Deuk Lee

Establishment of analytical method for cyazofamid residue in apple, mandarin, korean cabbage, green pepper, potato and soybean

A precise single residue analytical method was developed for fungicide cyazofamid in various crops. Apple, mandarin, Korean cabbage, green pepper, potato, and soybean were selected as representative crops, and clean-up system, partition solvent and extraction solvent were optimized. Limit of quantitation (LOQ) of cyazofamid was 2 ng (S/N>10) and good reproducibility was observed with small coefficient of variation (<4%). Excellent linearity was achieved between 0.05 and 20 mg/kg of cyazofamid standard solutions, with coefficients of determination of 1.000. Method limit of quantitation (MLOQ) was 0.02 mg/kg. For recoveries tests, crop samples were macerated and fortified with cyazofamid standard solution at three fortification levels (MLOQ, 10 MLOQ, and 100 MLOQ). And then those were extracted with acetone, concentrated and partitioned with dichloromethane. Then the extracts were concentrated again and cleaned-up through Florisil® column with ethyl acetate: n-hexane (30:70, v/v) before concentration and analysis with HPLC. Good recoveries from 75.3 to 98.5% with coefficients of variation of less than 10% were obtained, regardless of sample type, which satisfies the criteria of KFDA. Those results were reconfirmed with LC-MS/MS. The method established in this study could be applied to most of crops as an official and general method for residue analysis of cyazofamid.

Simultaneous Determination of Orysastrobin and Its Isomers in Rice Using HPLC-UV and LC-MS/MS

Orysastrobin is a new strobilurin-type fungicide to control leaf and panicle blast and sheath blight in rice. An analytical method was developed to determine the residues of orysastrobin and its two isomers, the main metabolite F001 and the major impurity F033, in hulled rice by the use of high-performance liquid chromatography with ultraviolet photometry (HPLC-UV) and liquid chromatography with tandem mass spectrometry (LC-MS/MS). All compounds were extracted with acetone from hulled rice samples. The extract was diluted with saline water, and an extraction step using dichloromethane/n-hexane partition was used to recover analytes from the aqueous phase. An n-hexane/acetonitrile partition and Florisil column chromatography were employed to further remove interfering coextractives prior to instrumental analysis. An octadecylsilyl column was successfully applied to identify orysastrobin and its isomers in sample extracts. Net recovery rates of orysastrobin, F001, and F033 from fortified samples ranged from 80.6 to 114.8% using HPLC-UV and LC-MS/MS. Relative standard deviations for the analytical methods were all <20%, and the quantification limits of the method were in the 0.002-0.02 mg/kg range. The proposed methods were reproducible and sufficiently accurate to evaluate the terminal residue of orysastrobin and its isomers in rice.

A single residue method for the determination of chlorpropham in representative crops using high performance liquid chromatography

A single residue analytical method was developed for herbicide chlorpropham in various crops. Brown rice, apple, mandarin, Kimchi cabbage, green pepper, potato, and soybean were selected as representative crops, and clean-up system, partition solvent, and extraction solvent were optimized. For high performance liquid chromatography (HPLC), C18 column was used with elution solvents of water and acetonitrile. Limit of quantitation (LOQ) of chlorpropham was 2 ng (S/N >20), and excellent linearity (R2=1.000) was achieved. Method limit of quantitation (MLOQ) was 0.02 mg/kg. For recovery tests, crop samples were macerated and fortified with chlorpropham standard solution at three fortification levels (MLOQ, 10 MLOQ, and 100 MLOQ). And then those were extracted with acetonitrile, concentrated and partitioned with n-hexane. The n-hexane layer was then concentrated, cleaned-up through Florisil® column with ethyl acetate:n-hexane (5:95, v/v) prior to concentration and analysis with HPLC. Good recoveries from 76.8 to 107.9% with coefficients of variation of less than 10% were obtained, regardless of sample type, which satisfies the criteria of Korea Food and Drug Administration. Those results were confirmed with liquid chromatography-mass spectrometry (LC-MS). The method established in this study could be applied to most of crops as an official and general method for the analysis of chlorpropham residue.

Determination of Buprofezin Residues in Rice and Fruits Using HPLC with LC/MS Confirmation

A high-performance liquid chromatographic (HPLC) method was developed to determine buprofezin residues in hulled rice and fruits. The buprofezin residue was extracted with acetone and the extract was stepwise purified by liquid-liquid partition and Florisil column chromatography. For rice samples, acetonitrile/ n-hexane partition was additionally employed to remove nonpolar lipids. Reversed phase HPLC using an octadecylsilyl column was successfully applied to separate buprofezin from sample co-extractives, as detected by ultraviolet absorption at 250 nm. Recovery experiment at the limit of quantitation validated that the proposed method could evidently determine the buprofezin residue at the level of 0.02 mg/kg. Mean recoveries from hulled rice, apple, pear, and persimmon samples fortified at three tenfold levels were in the range of 80.8~85.2%, 89.1~98.4%, 88.8~95.7% and 90.8~96.2%, respectively. Relative standard deviations of the analytical method were all less than 5%, irrespective of sample types. A selected-ion monitoring LC/mass spectrometry with positive electrospray ionization was also provided to sensitively confirm the suspected residue.

Development of an Official Method forMeasurement of Fluazinam Residues for Quarantine of Imported and Exported Horticultural Products

Department of Herbal Medicine Resource, Kangwon National University, Samcheok 25949, Korea 2 Pesticide and Veterinary Drug Residues Division, National Institute of Food and Drug Safety Evaluation, Ministry of Food and Drug Safety, Osong 28159, Korea Department of Horticultural Science, Kyungpook National University, Daegu 41566, Korea Division of Life and Environmental Science, Daegu University, Gyeongsan 38453, Korea

Establishment of Pre-Harvest Residue Limit (PHRL) of the Fungicide Amisulbrom during Cultivation of Winter-Grown Cabbage

Establishment of Pre-Harvest Residue Limit(PHRL) of the Fungicide Amisulbrom during Cultivation of Winter-Grown Cabbage Kyung-Geun Ahn, Gyeong-Ha Kim, Gi-Ppeum Kim, Min-Ji Kim, Seung-Beom Hong, Young-Sun Hwang, Chan-Hyeok Kwon, Young Wook Son, Young Deuk Lee and Myoung-Gun Choung* (Department of Herbal Medicine Resource, Kangwon National University, Samcheok, 245-711, Korea, Department of Biology, University of Texas-Arlington, Arlington, TX 76019, USA, Food Standard Division, Ministry of Food and Drug Safety, Cheongju, 363-700, Korea, Division of Life and Environmental Science, Daegu University, Gyeongsan, 712-714, Korea)

Development of Analytical Method for Fipronil Residues in Agricultural Commodities Using GC-ECD/MS

Development of Analytical Method for Fipronil Residues in Agricultural Commodities Using GC-ECD/MS Kyung-Geun Ahn, Gyeong-Ha Kim, Gi-Ppeum Kim, Young-Sun Hwang, In-Kyu Kang, Young Deuk Lee, and Myoung-Gun Choung (Department of Herbal Medicine Resource, Kangwon National University, Samcheok 25949, Korea, Department of Biology, University of Texas-Arlington, Arlington, TX 76019, USA, Department of Horticultural Science, Kyungpook National University, Daegu 41566, Korea, Division of Life and Environmental Science, Daegu University, Gyeongsan 38453, Korea)

High Performance Liquid Chromatographic Method for Determination of Metazosulfuron Residue in Representative Crops

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 (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/N10) 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.

Liquid Chromatographic Determination of Etofenprox Residues in Foods with Mass-Spectrometric Confirmation

BACKGROUND: An official analytical method was developed to determine etofenprox residues in agricultural commodities using high-performance liquid chromatography (HPLC). METHODS AND RESULTS: The etofenprox residue was extracted with acetone from representative samples of five raw products which comprised rice grain, apple, mandarin, cabbage, and soybean. The extract was then serially purified by liquid-liquid partition and Florisil column chromatography. For rice and soybean samples, acetonitrile/n-hexane partition was additionally coupled to remove nonpolar lipids. Reversed phase HPLC using an octadecylsilyl column was successfully applied to separate etofenprox from co-extractives. Intact etofenprox was sensitively detected by ultraviolet absorption at 225 nm. Recovery experiment at the quantitation limit validated that the proposed method could apparently determine the etofenprox residue at 0.02 mg/kg. Mean recoveries from five crop samples fortified at three levels in triplicate were in the range of 93.6∼106.4%. Relative standard deviations of the analytical method were all less than 10%, irrespective of crop types. A selected-ion monitoring LC/mass spectrometry with positive atmospheric-pressure chemical ionization was also provided to confirm the suspected residue.