Gyu-Seek Rhee

Establishment of Analytical Method for 6- Benzylaminopurine Residue, a Plant Growth Regulator for Brown Rice, Mandarin, Pepper, Potato, and Soybean by Using GC/NPD

Improvement of an analytical method on 6-benzylaminopurine (BAP), a plant growth regulator, and a first-generation synthetic cytokinin for agricultural commodities was undertaken. Analytical method for BAP in the agricultural commodities by gas chromatography in cooperation with nitrogen-phosphorous detector (NPD) was adopted. BAP was extracted with acetone in all samples followed by the ion-associated partitioning method. Vapor pressure of BAP was increased by N-methylation with iodide methane [BAP→6-Benzylamino-N-methylpurine (BAMP)]. Finally, N-methylated BAMP was separated with ethylacetate. The quantitation was done by GC using Nitrogen Phosphorous Detector with DB-608, a moderate polarity column under the temperature-rising condition. The standard calibration curve presented the linearity of correlation coefficient (r2)>0.9999, analyzed from 0.2 to 4 mg/kg. The limit of quantitation in agricultural commodities showed 0.05 mg/kg. The average recoveries of intraand inter-day experiments ranged from 70.4 to 103.5% and 70.3 to 105.6%, respectively. The repeatability and reproducibility for intra- and inter-day measurements expressed as a relative standard deviation (RSD) was less than 10.7 and 8.3%, respectively. Therefore, our newly established analytical method for BAP residue in agricultural commodities was applicable to the nationwide pesticide residues monitoring program with the acceptable level of sensitivity, repeatability and reproducibility.

Detection of pyridaben residue levels in hot pepper fruit and leaves by liquid chromatography-tandem mass spectrometry: effect of household processes.

Following quick, easy, cheap, effective, rugged and safe (QuEChERS) and LC/MS/MS analysis, pyridaben residual levels were determined in unprocessed and processed hot pepper fruit and leaves. The linearities were satisfactory with determination coefficients (R(2)) in excess of 0.995 in processed and unprocessed pepper fruit and leaves. Recoveries at various concentrations were 79.9-105.1% with relative standard deviations ≤15%. The limits of quantitation of 0.003-0.012 mg/kg were very low compared with the maximum residue limits (2-5 mg/kg) set by the Ministry of Food and Drug Safety, Republic of Korea. The effects of various household processes, including washing, blanching, frying and drying under different conditions (water volume, blanching time and temperature) on residual concentrations were evaluated. Both washing and blanching (in combination with high water volume and time factor) significantly reduced residue levels in hot pepper fruit and leaves compared with other processes. In sum, the developed method was satisfactory and could be used to accurately detect residues in unprocessed and processed pepper fruit and leaves. It is recommended that pepper fruit/leaves be blanched after washing before being consumed to protect consumers from the negative health effects of detected pesticide residues.

Development of an Official Analytical Method for Determination of Phorate and its Metabolites in Livestock Using LC-MS/MS

A simultaneous official method was developed for the determination of phorate and its metabolites (phorate sulfoxide, phorate sulfone, phorate oxon, phorate oxon sulfoxide, phorate oxon sulfone) in livestock samples. The analytes were quantified and confirmed via liquid chromatograph-tandem mass spectrometer (LC-MS/MS) in positive ion mode using multiple reaction monitoring (MRM). Phorate and its metabolites were extracted from beef and milk samples with acidified acetonitrile (containing 1% acetic acid) and partitioned with anhydrous magnesium sulfate. Then, the extract was purified through primary secondary amine (PSA) and C18 dispersive sorbent. Matrix matched calibration curves were linear over the calibration ranges (0.005-0.5 mg/L) for all the analytes into blank extract with r > 0.996. For validation purposes, recovery studies were carried out at three different concentration levels (beef 0.004, 0.04 and 0.2 mg/kg; milk 0.008, 0.04 and 0.2 mg/kg, n = 5). The recoveries were within 79.2-113.9% with relative standard deviations (RSDs) less than 19.2% for all analytes. All values were consistent with the criteria ranges requested in the Codex guidelines. The limit of quantification was quite lower than the maximum residue limit (MRL) set by the Ministry of Food and Drug Safety (0.05 mg/kg). The proposed analytical method was accurate, effective and sensitive for phorate and its metabolites determination and it will be used to as an official analytical method in Korea.

Development and Validation of an Analytical Method for Flutianil Residue Identification Using Gas Chromatography-Electron Capture Detection

Ji-Eun Kwon, Jung-Ah Do, Hyejin Park, Ji-Young Lee, Yoon-Jae Cho,Jae-Ho Oh, Gyu-Seek Rhee, Sang-Jae Lee, and Moon-Ik Chang*Food Safety Evaluation Department, National Institute of Food and Drug Safety Evaluation, MFDSAbstract A sensitive and simple analytical method to identify flutianil residues in agricultural commodities wasdeveloped and validated using gas chromatography-electron capture detection (GC-ECD) and mass spectrometry (GC-MS).The flutianil residues were extracted with acetonitrile, partitioned with dichloromethane, and then purified using a silicasolid-phase extraction (SPE) cartridge. The method was validated using pepper, sweet pepper, mandarin, hulled rice,soybean, and potato spiked with 0.02 or 0.2 mg/kg flutianil. The average recovery of flutianil was 76.5-108.0% with arelative standard deviation of less than 10%. The limit of detection and limit of quantification were 0.004 and 0.02 mg/kg, respectively. The result of recoveries and relative standard deviation were in line with Codex Alimentarius CommissionGuidelines (CAC/GL 40). These results show that the method developed in this study is appropriate for flutianilidentification and can be used to maintain the safety of agricultural products containing flutianil residues.Keywords: flutianil, fungicide, GC-ECD, GC-MS, agricultural commodities

Establishment of Analytical Method for Dichlorprop Residues, a Plant Growth Regulator in Agricultural Commodities Using GC/ECD

BACKGROUND: This study focused on the development of an analytical method about dichlorprop (DCPP; 2-(2,4-dichlorophenoxy)propionic acid) which is a plant growth regulator, a synthetic auxin for agricultural commodities. DCPP prevents falling of fruits during their growth periods. However, the overdose of DCPP caused the unwanted maturing time and reduce the safe storage period. If we take fruits with exceeding maximum residue limits, it could be harmful. Therefore, this study presented the analytical method of DCPP in agricultural commodities for the nation-wide pesticide residues monitoring program of the Ministry of Food and Drug Safety.

Simultaneous Determination of Aminoglycoside Antibiotics in Meat using Liquid Chromatography Tandem Mass Spectrometry

A simultaneous determination was developed for 9 aminoglycoside antibiotics (amikacin, apra- mycin, dihydrostreptomycin, gentamicin, hygromycin B, kanamycin, neomycin, spectinomycin, and streptomycin) in meat by liquid chromatography tandem mass spectrometry (LC-MS/MS). Each parameter was established by multiple reaction monitoring in positive ion mode. The developed method was validated for specificity, linearity, accuracy, and precision based on CODEX validation guideline. Linearity was over 0.98 with calibration curves of the mixed stan- dards. Recovery of 9 aminoglycosides ranged on 60.5~114% for beef, 60.1~112% for pork and 63.8~131% for chicken. The limit of detection (LOD) and limit of quantification (LOQ) were 0.001~0.009 mg/kg and 0.006~ 0.03 mg/kg, respectively in livestock products including beef, pork and chicken. This study also performed survey of residual aminoglycoside antibiotics for 193 samples of beef, pork and chicken collected from 9 cities in Korea. Ami- noglycosides were not found in any of the samples.

Establishment of an Analytical Method for Determination of Fungicide Oxathiapiprolin in Agricultural Commodities using HPLC-UV Detector

An analytical method was developed for the determination of oxathiapiprolin in agricultural commodities. Oxathiapiprolin is a new oomycide (fungicide of piperidinyl thiazole isoxazoline class) which controls downy mildew in cucurbits caused by Pseudoperonospora cubensis (oomycete plant pathogen). Agricultural commodities were extracted with acetonitrile and partitioned with dichloromethane to remove the interference, adjusting pH between 9 and 10 by 1 N sodium hydroxide. After purification by silica SPE cartridge to clean up the interference of organic compounds, they were finally quantified by HPLC-UVD (high performance liquid chromatograph ultraviolet detector) using a wavelength at 260 nm and confirmed by LC-MS (liquid chromatograph mass spectrometer) in electro-spray ionization positive ion mode. The standard calibration curve was linear with coefficients of determination (r) 1.00 over the calibration ranges (0.025-2.5 mg/L). Recoveries were ranged between 86.7 to 112.7%, with relative standard deviations less than 10% at three concentration levels (LOQ, 10LOQ, and 50LOQ) performing five replicates. The overall results were determined and estimated according to the CODEX guidelines (CAC/GL40). The proposed method for determination of oxathiapiprolin residues in agricultural commodities can be used as an official method.

Development of analytical method for determination of spinetoram residues in livestock using LC-MS/MS

Abstract: An analytical method was developed to determine the amount of spinetoram (spinetoram J andspinetoram L) in livestock samples. The spinetoram was extracted with acetonitrile and purified through a primarysecondary amine (PSA) sorbent. The spinetoram residues were then quantified and confirmed using a liquidchromatography–tandem mass spectrometer (LC-MS/MS) in the positive ion mode using multiple reactionsmonitoring (MRM). Matrix-matched calibration curves were linear over the calibration ranges (0.005-0.5 mg/kg)into a blank extract with r 2 > 0.994. The limits of detection and quantification were 0.002 and 0.01 mg/kg,respectively. The recovery results of spinetram ranged between 81.9-106.4% at different concentration levels (LOQ,10LOQ, 50LOQ, n=5) with relative standard deviations (RSDs) less than 10%. All values were consistent withthe criteria ranges requested in the Codex guidelines (CAC/GL40, 2003). An interlaboratory study was conductedto validate the method. The proposed analytical method proved to be accurate, effective, and sensitive for spinetoramdetermination. The method will be used as an official analytical method in Korea.요약: 이 연구는 수입을 포함한 국내 유통 축산물 중 spinetoram의 안전관리를 위한 공정시험법을 확립하기 위해 수행하였으며 시험법의 선택성, 검출한계 및 정량한계, 회수율에 대한 검증을 통하여 공정시험법으로의 유효성을 확인하였다. Spinetoram을 효과적으로 분석하기 위하여 LC-MS/MS를 분석기기로 사용하였고, acetonitrile으로 추출 후 PSA를 이용한 d-SPE정제법을 적용하여 시료의 불순물을 정제하

Development and Validation of an Official Analytical Method for Determination of Ipfencarbazone in Agricultural Products using GC-ECD

Abstract Ipfencarbazone is a herbicide of the tetrazolinone class, and is believed to be an inhibitor of verylong chain fatty acids (VLCFAs), which control cell division in weeds. The objective of this study was todevelop and validate an official analytical method for ipfencarbazone determination in agricultural products.The ipfencarbazone residues in agricultural products were extracted with acetone, partitioned with n-hexane,and then purified through silica SPE cartridge. Finally, the analyte was quantified by gas chromatograph-electron capture detector (GC-ECD) and confirmed with gas chromatograph/mass spectrometer(GC/MS). Thelinear range of ipfencarbazone was 0.01 to 1.0 mg/L with the coefficient of determination (r 2 ) of 0.9999. Thelimit of detection (LOD) and quantification (LOQ) was 0.003 and 0.01 mg/kg, respectively. In addition,average recoveries of ipfencarbazone ranged from 80.6% to 112.3% at the different concentration levels LOQ,10LOQ and 50LOQ, while the relative standard deviation was 2.2-8.6%. All values were consistent with thecriteria ranges requested in the CODEX guidelines. Furthermore, and inter-laboratory study was conducted tovalidate the method. This proposed method for determination of ipfencarbazone residues in agriculturalproducts can be used as an official analytical method.Key words Ipfencarbazone, GC-ECD, GC/MS, Herbicide, Maximum Residue Limits

Establishment of Analytical Method for Residues of Ethychlozate, a Plant Growth Regulator, in Brown Rice, Mandarin, Pepper, Potato, and Soybean Using HPLC/FLD

Received: 8 April 2015 / Revised: 20 April 2015/ Accepted: 12 June 2015 Copyright c 2015 The Korean Society of Environmental Agriculture This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.