Yoon-Jae Cho

Determination of optical purity of 3,5-dimethoxybenzoyl-leucine diethylamide by chiral chromatography and 1H and 13C NMR spectroscopy

(R)-N-3,5-dinitrobenzoyl (DNB) leucine derived chiral selector was used as an HPLC chiral stationary phase for the resolution of various racemic amino acids derivatives. In this study, determination of optical purity of an amino acid derivative was performed by chiral high performance liquid chromatography and 1H and 13C NMR spectroscopy by using the DNB leucine derived chiral selector. The accuracy and precision of each optical purity value are calculated and the data are compared to each other.

A triple-isotope approach for discriminating the geographic origin of Asian sesame oils.

The aim of this study was to investigate the effects of the geographic location and climatic characteristics of the sesame-producing sites on the carbon, hydrogen, and oxygen stable isotope ratios of Korean sesame oil. In addition, the study aimed to differentiate Korean sesame oil from Chinese and Indian sesame oils using isotopic data in combination with canonical discriminant analysis. The isotopic data were obtained from 84 roasted oil samples that were prepared from 51 Korean, 19 Chinese, and 14 Indian sesame seeds harvested during 2010-2011 and distributed in Korea during the same period. The δ(13)C, δD, and δ(18)O values of Korean sesame oil were negatively correlated with latitude, distance from the sea, and precipitation (May-September), respectively. By applying two canonical discriminant functions, 89.3% of the sesame oil samples were correctly classified by their geographic origin, indicating that the triple-isotope approach is a useful tool for the traceability of the oils.

Development and validation of an analytical method for pyrimisulfan determination in agricultural commodities by LC-MS/MS

The maximum residue limits of pyrimisulfan is set as 0.05 mg/kg in rice in 2011, so very reliable and sensitive analytical method for pyrimisulfan residues is required for ensuring the food safety of pyrimisulfan residues in agricultural products. In this study, a rapid and sensitive analytical method was developed and validated using liquid chromatography electrospray ionization tandem mass spectrometry (LC-MS/MS) for the determination of herbicide pyrimisulfan residues in agricultural products. Average recoveries of pyrimisulfan ranged from 88.7 to 99.3% at the spiked level of 0.005 mg/kg and from 90.1 to 94.2% at the spiked level of 0.05 mg/kg, while the relative standard deviation was less than 10%. Linear range of pyrimisulfan was between 0.01~1.0 with the correlation coefficient () 0.999 and limit of quantification was 0.005 mg/kg. The results of method validation were satisfied Codex guideline. The results revealed that the developed and validated analytical method is possible for pyrimisulfan determination in agricultural product samples and will be used as an official analytical method.

Development and Validation of an Analytical Method for the Insecticide Sulfoxaflor in Agricultural Commodities using HPLC-UVD

Sulfoxaflor is a new active ingredient within the sulfoximine insecticide class that acts via a unique interaction with the nicotinic receptor. The MRLs (maximun residue limit) of sulfoxaflor in apple and pear are set at 0.4 mg/kg and that in pepper is set at 0.5 mg/kg. The purpose of this study was to develop an analytical method for the determination of sulfoxaflor residues in agricultural commodities using HPLC-UVD and LC-MS. The analysis of sulfoxaflor was performed by reverse phase-HPLC using an UV detector. Acetone and methanol were used for the extraction and aminopropyl (NH2) cartridge was used for the clean-up in the samples. Recovery experiments were conducted on 7 representative agricultural products to validate the analytical method. The recoveries of the proposed method ranged from 82.8% to 108.2% and relative standard deviations were less than 10%. Finally, LC-MS with selected ion monitoring was also applied to confirm the suspected residues of sulfoxaflor in agricultural commodities.

Development and Validation of an Analytical Method for Ametoctradin Residue Determination in Domestic Agricultural Commodities by HPLC-PDA

This study was carried out to validate the safety of ametoctradin residues in agricultural commodities by developing an official analysis method. An analytical method was developed and validated using HPLC-PDA detectors. The samples were extracted with methanol, subsequently partitioned with dichloromethane and purified with florisil column chromatograph using acetone/hexane (30/70, v/v) as solvent. The method was validated by using grape, hulled rice, mandarin, and potato spiked with ametoctradin at 0.05 and 5.0 mg/kg, and pepper at 0.05 and 2.0 mg/kg. Average recoveries were 76-114.8% with relative standard deviation less than 10%, and the limit of detection and limit of quantification were 0.0125 and 0.05 mg/kg, respectively. The result of recoveries and overall coefficient of variation of the laboratory results from Gwangju regional Food and Drug Administration (FDA) and Daejeon regional FDA was accorded with Codex Alimentarius Commission Guideline (CAC/GL 40). Based on these results, this method was found to be appropriate for ametoctradin residue determination and can be used as the official method of analysis.

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

Improvement of an Simultaneous Determination for Clenbuterol and Ractopamine in Livestock Products using LC-MS/MS

Clenbuterol and ractopamine, which are β-agonists, have been misused as a growth promoting agent in meat producing animals. Clenbuterol was banned for veterinary drug in Korea because of its problems regarding safety. Due to their adverse effects, such as cardiovascular and central nervous diseases on human health proper control and monitoring should be conducted. The existing analytical method of clenbuterol and ractopamine in the Food code was improved through our present study. The bovine muscle samples were subjected to enzymatic hydrolysis, extracted with ethyl acetate and defatted by hexane-methanol partitioning. A molecular imprinted polymer (MIP) solid phase extraction cartridge was used for clean-up and LC-MS/MS was operated in positive multiple reaction monitoring (MRM). Clenbuterol-d 9 and ractopamine-d3 were used as an internal standard. The renewed method was validated according to the CODEX guideline. The limits of quantitation for clenbuterol and ractopamine were 0.2 and 0.5 µg/kg, respectively. The mean recoveries ranged in 104.2-113.5% for clenbuterol and in 107.6-118.1% for ractopamine. The improved method was able to save both time and expenses.

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.

Development and validation of analytical methods for pyrifluquinazon residues determination on agricultural commodities by HPLC-UVD

Pyrifluquinazon is classified with a quinazoline insecticide that regulates food intake by controling the feeding behavior acting on the endocrine or nervous system of pests such as aphids and white fly. To keep safety on pyrifluquinazon residues in agricultural commodities a simple, accurate and rapid analytical method was developed and validated using high performance liquid chromatograph (HPLC-UVD). The pyrifluquinazon residues acidified with 1% formic acid in samples were extracted with acetonitrile and partitioned with hexane subsequently to dichloromethane then purified with silica solid phase extraction (SPE) cartridge. The purified samples were detected using HPLC-UVD. The method was validated using apple and pear spiked with pyrifluquinazon at 0.02, 0.05 and 0.1 mg/kg and hulled rice, pepper, soybean at 0.05 and 0.1 mg/kg. Average recoveries were 70.5~107.9% with relative standard deviation less than 10%. The result of recoveries and overall coefficient of variation of a laboratory results in Gwangju regional FDA and Daejeon regional FDA was followed with Codex guideline (CODEX CAC/GL 40). This method is appropriated at pyrifluquinazon residues determination and will be used as official method of analysis.

A Study on Stable Isotope Ratio of Circulated Honey in Korea

This study examines the authenticity discrimination of the circulated honey by using stable isotope ratio methods. In the case of domestic honey, the range of δ 13 C for the samples labeled as pure honey was about −27- −21‰ at the C 3 origin, and the range of that for artificial honey was over −19‰ at the C 4 origin. The range of δ 13 C for all imported honey was over −27- −23‰ originating from the C3 plant. According to the nectar-source, δ 2 H and δ 18 O for domestic honey were significantly different for 6 and 5 groups, respectively. However, we could not explain the detailed relationship as well as the geographical feature of δ 2 H and δ 18 O. The difference for δ 2 H and δ 18 O in the wide range of latitude, such as between Australia and Canada, was more or less shown. However, it was difficult to find out the trends of δ 2 H and δ 18 O for imported honey versus the geographical information in the similar latitudinal country.