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Sub-chronic toxicity studies using rats have been conducted for Cynanchum wilfordii (Maxim.) Hemsley (CW) and Cynanchum auriculatum Royle ex Wight (CA). CW water extract didn’t show any adverse effects whereas administering CW powder decreased body weights in complication with decreased food consumptions. In the case of CA water extract, triglyceride and absolute/relative liver weights were elevated and vacuolation was observed in liver. Treated CA powder in male rats increased alanine aminotransferase and aspartate aminotransferase and induced single cell necrosis and multinucleated hepatocyte in liver. As for female rats, increased absolute/relative weights and hypertrophy/vacuolation in adrenal glands and vacuolation in ovaries were observed when administered CA powder. In conclusion, no observed adverse effect level (NOAEL) of CW water extract was over 5000 mg/kg/day, while NOAEL of CW powder was 700 mg/kg/day for female and 150 mg/kg/day for male. In case of CA, NOAEL of water extract was 1500 mg/kg/day for male and 2000 mg/kg/day for female, while NOAEL of powder was 150 mg/kg/day for both gender. To the best of our knowledge, this is the first sub-chronic toxicity study on the adverse effects, target organs and its dose levels of C. wilfordii (Maxim.) Hemsley and C. auriculatum Royle ex Wight following GLP protocols.

Korean firms have been vigorously searching and exploring overseas market opportunities through export and overseas investment. As of end of 2019, there were more than 80,000 Korean overseas subsidiaries all over the world. With Korean overseas direct investment increasing recently, it became one of the important issues for overseas investors to be successful in the global market. There are a lot of studies on factors influencing the performance of overseas subsidiaries such as ‘firm’ and ‘country’ factors. This study empirically examines subsidiary performance determinants with ‘industry architectures’ by using a sample of 292 overseas Korean firm subsidiaries. Industry architectures are the stable but evolving sets of rules and roles through which labor is divided within a sector. This article considers how industry architectures shape success in international expansion. Industry architectures differ between countries, are not necessarily technologically determined, shape firms’ capabilities and their competitive environment, and constitute a distinct level of analysis. We extract antecedents of related theory and empirically test its impact with a survey of Korean firms expanding in emerging economies. We would say this is the first study which tries to focus on industry architectures with the performance of Korean overseas subsidiaries. We find that separability and similarity of industry architectures across countries and localization of subsidiaries are robust and important predictors of success in international expansion. Our results suggest that industry architectures should be added to firm and country as an intermediate level of analysis that helps explain success in international expansion. While we established a pattern, much more remains to be done. We focus on the success of foreign operations, but we do not consider the broader benefits of going abroad, such as the learning or network effects that accrue at the level of the entire firm. The next obvious question is whether the results would differ in the developed market context. These we leave for future research to consider.

BACKGROUND: Pinoxaden is the phenylpyrazoline herbicide developed by Syngenta Crop Protection, Inc. and marketed on 2006. The maximum residue levels for wheat and barley were set by import tolerance. Thus, Ministry of Food and Drug Safety (MFDS) official analytical method determining Pinoxaden residue was necessary in various food matrixes. Satisfaction of international guideline of CODEX (Codex Alimentarius Commission CAC/GL 40) and National Institute of Food and Drug Safety Evaluation- MFDS (2017) are additional pre-requirements for analytical method. In this study, liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was investigated to analyze residue of Pinoxaden (M4), which is defined as pesticide residue in Korea, in foods. METHODS AND RESULTS: Pinoxaden (M4) was extracted followed by acid digestion (2hr reflux with 1N HCl) and pH adjusting (pH 4-5 with 3% ammonium solution). To remove oil, additional clean-up step with hexane saturated with acetonitrile was required to high oil contained sample before purification. HLB cartridge and nylon syringe filter were used for purification. Then, samples were analyzed by LC-MS/MS using reserve phase column C18. Five agricultural group representative commodities (mandarin, potato, soybean, hulled rice, and red pepper) were used to verify the method in this study. The liner matrix-matched calibration curves were confirmed with coefficient of determination (r2) > 0.99 at calibration range 0.002-0.2 mg/kg. The limits of detection and quantitation were 0.004 and 0.01 mg/kg, respectively, which were suitable to apply Positive List System (PLS). Mean average accuracies of pinoxaden (M4) were shown to be 74.0-105.7%. The precision of pinoxaden and its metabolites were also shown less than 14.5% for all five samples. CONCLUSION: The method investigated in this study was suitable to CODEX (CAC/GL 40) and National Institute of Food and Drug Safety Evaluation-MFDS (2017) guideline for residue analysis. Thus, this method can be useful for determining the residue in various food matrixes in routine analysis.

Nowadays, various industries using nanomaterials are growing rapidly, and in particular, as the commercialization and use of nanomaterials increase in the cosmetic field, the possibility of exposure of nanomaterials to the skin of product producers and consumers is increasing. Due to the unique properties of nanomaterials with a very small size, they can act as hapten and induce immune responses and skin sensitization, so accurate identification of toxicity is required. Therefore, we selected silica nanomaterials used in various fields such as cosmetics and biomaterials and evaluated the skin sensitization potential step-by-step according to in-vitro and in-vivo alternative test methods. KeratinoSensTM cells of modified keratinocyte and THP-1 cells mimicking dendritic-cells were treated with silica nanoparticles, and their potential for skin sensitization and cytotoxicity were evaluated, respectively. We also confirmed the sensitizing ability of silica nanoparticles in the auricle-lymph nodes of BALB/C mice by in-vivo analysis. As a result, silica nanoparticles showed high protein binding and reactive oxygen species (ROS) mediated cytotoxicity, but no significant observation of skin sensitization indicators was observed. Although more studies are needed to elucidate the mechanism of skin sensitization by nanomaterials, the results of this study showed that silica nanoparticles did not induce skin sensitization.

A rapid and simple analytical method for triflumezopyrim, a new class of mesoionic insecticides and commercialized molecules from DuPont, was developed with a modified QuEChERS method. The pH adjustment was used to improve the extraction efficiency of acetonitrile solvent, and dispersive solid-phase extraction was employed for the clean-up process. The five selected food commodities were used to verify the present optimized method, which displayed good linearity with an excellent correlation coefficient (R2 = 0.9992–0.9998) in the 0.003–0.30 mg/kg calibration range. The method limits of detection (LOD) and quantification (LOQ) were determined to be a value of 0.003 and 0.01 mg/kg, respectively. The mean recovery for the triflumezopyrim was in the 89.7–104.3% range. The relative standard deviations were ≤9.8% for intra- (n = 5) and inter-day (n = 15) precisions at concentrations of 0.01, 0.1, and 0.5 mg/kg in the five representative samples. The matrix effect has been calculated to confirm the effect during ionization of the analyte in the UPLC-MS/MS. The matrix effects of the instrumental analysis showed that triflumezopyrim was less susceptible to matrices. The proposed analytical method in this study has effectively improved the accuracy, selectivity, and sensitivity for the determination of triflumezopyrim in agricultural commodities, therefore, it can serve as a reference method for the establishment of maximum residue limits (MRLs).

Bromochlorophene (BCP) has shown good properties in sterilization and antibacterial activity and is widely used as a household chemical. We evaluated the genotoxicity, single and repeated-dose 28-day oral toxicity, and dermal application of a BCP suspension in Sprague–Dawley (SD) rats. For the single-dose toxicity study, a dose of 25–1,000 mg per kg of bodyweight (mg/kg b.w.) of BCP was given once orally to SD rats. Mortality and clinical signs were observed and recorded for the first 30 min after treatment, at 4 h post-administration, and then at least once daily for 14 days after administration. For the repeated-dose 28-day toxicity study, the high dose was set at 1,000 mg/kg b.w. and the middle, middle-low, and low dose were set to 500, 250, and 125 mg/kg, respectively. Hematology and biochemistry parameters were examined. Gross pathologic and histopathologic examinations were performed on selected tissues from all animals. A bacterial reverse mutation assay, in vitro chromosomal aberration assay, and in vivo micronucleus assay were performed to assess genotoxicity-dermal application exposure assessment of BCP in rats. A high oral approximate lethal dose (ALD) of 1,000 mg/kg was observed in the single-dose toxicity test. During the repeated-dose 28-day time period, most animal deaths after administration occurred during the first 3 weeks. The 1,000 mg/kg b.w. oral dose caused the death of six male rats (6/7) and four female rats (4/7). At 500 mg/kg b.w., the female rats showed mortality (1/7). For the biochemistry assays, cholesterol was increased significantly compared to vehicle in both sexes in the 250 and 500 mg/kg groups. Histopathological changes with treatment-related findings were observed in the pancreas in female rats treated with a high dose of BCP compared with the vehicle group. BCP showed no genotoxic effect. These data suggested that the ALD of BCP, estimated as a non-genotoxic substance, was over 1,000 mg/kg b.w. in the single-dose toxicity study, and the NOAEL of BCP was considered to be 250 mg/kg b.w. for male and female rats after repeated oral administration for 28 days under the present study conditions.

Human skins are exposed to nanomaterials in everyday life from various sources such as nanomaterial-containing cosmetics, air pollutions, and industrial nanomaterials. Nanomaterials comprising metal haptens raises concerns about the skin sensitization to nanomaterials. In this study, we evaluated the skin sensitization of nanomaterials comparing metal haptens in vivo and in vitro. We selected five metal oxide NPs, containing copper oxide, cobalt monoxide, cobalt oxide, nickel oxide, or titanium oxide, and two types of metal chlorides (CoCl2 and CuCl2), to compare the skin sensitization abilities between NPs and the constituent metals. The materials were applied to KeratinoSensTM cells for imitated skin-environment setting, and luciferase induction and cytotoxicity were evaluated at 48 h post-incubation. In addition, the response of metal oxide NPs was confirmed in lymph node of BALB/C mice via an in vivo method. The results showed that CuO and CoO NPs induce a similar pattern of positive luciferase induction and cytotoxicity compared to the respective metal chlorides; Co3O4, NiO, and TiO2 induced no such response. Collectively, the results implied fast-dissolving metal oxide (CuO and CoO) NPs release their metal ion, inducing skin sensitization. However, further investigations are required to elucidate the mechanism underlying NP-induced skin sensitization. Based on ion chelation data, metal ion release was confirmed as the major “factor” for skin sensitization.

To manage the safety of the herbicide metazachlor, analytical methods are required for the determination of metazachlor metabolites in agricultural crops. Herein, a liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed for the simultaneous determination of metazachlor metabolites (479M04, 479M08, and 479M16) in various agricultural commodities. After extraction using acetonitrile and adjusting the pH to 3, the samples were purified using a hydrophilic–lipophilic balance cartridge. The matrix-matched calibration curves (0.002–0.2 μg/mL) were linear (r2 > 0.99). For validation, recovery tests were carried out at three fortification levels (limit of quantification (LOQ), 10 LOQ, and 50 LOQ) in various agricultural samples. The recoveries of 479M04, 479M08, and 479M16 were 79.6–113.0, 76.9–97.7, and 79.1–102.1%, respectively, with relative standard deviation values of less than 17.0%. Furthermore, inter-laboratory testing was conducted to validate the method. All the values corresponded to the criteria of both the CODEX (CAC/GL 40-1993, 2003) and Ministry of Food and Drug Safety guidelines. Therefore, the proposed LC–MS/MS method can be used as an analytical method for the determination of metazachlor.

This study was performed to optimize the analytical method for multi-residues of 60 compounds in flatfish samples. Three sample preparation methods were tested to identify the optimal recovery conditions for target analytes. As a result, 10 mL of water/acetonitrile (1:4, v/v) was used to extract analytes from fish samples. For purification, C18 and 10 mL of acetonitrile saturated hexane were used to treat the samples. After evaporation and reconstitution, the fish samples were analyzed by ultra-performance liquid chromatography-tandem mass spectrometry. The proposed method was validated according to the CODEX guidelines (CAC/GL-71). Our results showed the recoveries of 73.2%&ndash, 115% and coefficients of variation of 1.6%&ndash, 22.1%. The limit of quantification was 0.0005&ndash, 0.005 mg/kg in the fishery products. In analysis of real samples, no samples exceeded the limit of quantification. This analytical method can be used for multi-residue screening and confirmation of the residues of veterinary drugs in fishery products.

The development of a universal, label-free, and reliable in vitro toxicity testing method for nanoparticles is urgent because most nanoparticles can interfere with toxicity assays. In this regard, the colony-forming efficacy (CFE) assay has been suggested as a suitable in vitro toxicity assay for testing nanoparticles without such interference. Recently, the Organisation for Economic Co-operation and Development (OECD) developed a 60 × 15 mm Petri dish-based CFE assay for testing nanoparticles in MDCK-1 cells. However, further investigations are needed, including testing with other cell types, at a smaller scale for greater efficiency, and the application of the co-culture technique. In this study, we selected TiO2, CuO, CeO2, and SiO2 as test nanoparticles and successfully developed a 6-well plate-based CFE assay using HepG2 and A549 cells and a co-culture assay for combinations of HepG2 cells and THP-1 macrophages or A549 cells and THP-1 monocytes. The results suggest that the 6-wellplate-based CFE assay for HepG2 and A549 cells can be applied to nanoparticles, but the co-culture CFE assay has limitations in that it is not different from the single culture study, and it inhibits colony-formation by A549 cells in the presence of macrophages; this warrant further study.

Objective To evaluate the compliance and satisfaction of rehabilitation recommendations for advanced cancer patients hospitalized in the palliative care unit. Methods Advanced cancer patients admitted to a hospice palliative care unit were recruited. Patients with advanced cancer and a life expectancy of less than 6 months, as assumed by the oncologist were included. Patients who were expected to die within 3 days were excluded. ECOG and Karnofsky performance scales, function ambulatory category, level of ambulation, and survival days were evaluated under the perspective of comprehensive rehabilitation. Problem-based rehabilitations were provided categorized as physical therapy at the gym, bedside physical therapy, physical modalities, medications and pain intervention. Investigation of compliance for each category was completed. Patient satisfaction was surveyed using a questionnaire. Results Forty-five patients were recruited and received evaluations for rehabilitation perspective. The subjects were reported to have gait-related difficulties (71.1%), pain (68.9%), poor medical conditions (68.9%), bladder or bowel problems (44.4%), dysphagias (11.1%), mental status issues (11.1%), edemas (11.1%), spasticity (2.2%), and pressure sores (2.2%). In the t-test, patients with good compliance for GymPT showed higher survival days (p

Graphene nanoplatelets (GNPs) are one of the major types of carbon based nanomaterials that have different industrial and biomedical applications. There is a risk of exposure to GNP material in individuals involved in their large-scale production and in individuals who use products containing GNPs. Determining the exact toxicity of GNP nanomaterials is a very important agenda. This research aimed to evaluate the skin sensitization potentials induced by GNPs using two types of alternative to animal testing. We analyzed the physicochemical characteristics of the test material by selecting a graphene nanomaterial with a nano-size on one side. Thereafter, we evaluated the skin sensitization effect using an in vitro and an in vivo alternative test method, respectively. As a result, we found that GNPs do not induce skin sensitization. In addition, it was observed that the administration of GNPs did not induce cytotoxicity and skin toxicity. This is the first report of skin sensitization as a result of GNPs obtained using alternative test methods. These results suggest that GNP materials do not cause skin sensitization, and these assays may be useful in evaluating the skin sensitization of some nanomaterials.

We aimed to estimate the dietary exposure level of ethoxyquin (EQ) and its main metabolite ethoxyquin dimer (EQDM) in 6 kinds of farmed aquatic animals based on the residues and aquatic animal consumption data from Korea. The residues were measured in 143 aquatic animal samples by LC-MS/MS. The dietary exposure level was estimated under four scenarios based on the WHO guidelines. The residue concentrations of EQ and EQDM were in the ranges of 0.14–24.2 and 0.1–315 μg/kg, respectively. The sum of aquatic animal consumption for six aquatic animals was 6.38 g/day (whole group) and 372 g/day (consumer only) in the national food consumption survey. Based on our results, there is no significant risk resulting from EQ and EQDM exposure of humans under all scenarios. This is the first study to present the residue concentrations and exposure levels of EQ and EQDM in farmed aquatic animals in Korea.

In May 2012, a safety hazard issue arose because some kiwifruit growers in New Zealand had sprayed streptomycin to prevent kiwifruit canker. Therefore, for food safety management, analytical methods to determine streptomycin residues in kiwifruits are required. We developed an analytical method to determine streptomycin residues in kiwifruit samples using liquid chromatograph tandem mass spectrometer (LC-ESI-MS/MS). Streptomycin residues in samples were extracted using 1% formic acid in methanol, centrifugation for 10 min, and subsequent supernatant filtration. Purified samples were subjected to LC-ESI-MS/MS to confirm presence of and quantify streptomycin residues. Average streptomycin recoveries (6 replicates each sample) were in the range of 94.8%-110.6% with relative standard deviations of 2 = 0.9995. The limit of quantification (LOQ) was 0.01 mg/kg. Results showed that our analytical method is rapid, simple, and sensitive, with easy sample preparation.

Tridemorph is a systemic morpholine fungicide for crops. The objective of this study was to develop reliable and sensitive analytical method for determination of tridemorph residues in tea samples for ensuring the food safety. Tridemorph residues in samples were extracted with acetonitrile after hydration, partitioned with saline water, and then purified using an aminopropyl (NH2) SPE cartridge. The purified samples were detected and quantified using LC-ESI-MS/MS. The linear detection limits for tridemorph ranged from 0.02 to 1.0 mg L �1 with a correlation coefficient of 0.9999. The method was validated using tea samples spiked with tridemorph at different con- centration levels (0.02 and 0.05 µ gm L �1 ). The average recovery ranged between 75.0 and 84.7% with relative standard deviations less than 10%. The LOD and LOQ were 0.01 and 0.02 mg L �1 , respectively. The developed method was applied successfully to the identification of tridemorph in real tea samples obtained from different sources, and tride- morph was not detected in any of the samples. The results show that the developed analytical method is accurate and suitable for tridemorph determination in tea samples.

Saflufenacil is a low-volatile and uracil-based herbicide. This herbicide is used for pre-and post- emergence control of major broadleaf weeds. The objective of present study was to develop and validate an analytical method for saflufenacil determination in agricultural products for ensuring the food safety. The saflufenacil residues in samples were extracted with acetone, dichloromethane, and then purified with silica and graphitized carbon car- tridge. The purified samples were analyzed by HPLC-UVD and confirmed with LC-MS. The linear range of saflufenacil was 0.1~5.0 µ gm L �1 with the correlation coefficient (r) = 0.999. Average recoveries of saflufenacil ranged from 80.5% to 110.2% at the spiked level of 0.02~0.5 mg kg �1 , while the relative standard deviation was 0.3~7.3%. In addition, the limit of detection and limit of quantification were 0.005 and 0.02 mg L �1 , respectively. Furthermore, an interlaboratory study among three labs was conducted to validate the method, and the results were satisfactory.

Imicyafos which is a nematicide for controlling root-knot nematodes has been registered in theRepublic of Korea in 2012, and the maximum residue limits of imicyafos are set to watermelon and koreanmelon as each 0.05 mg/kg. Extremely reliable and sensitive analytical method is required for ensuring foodsafety on imicyafos residues in agricultural commodities. Imicyafos residues in samples were extracted withacetone, partitioned with hexane and dichloromethane, and then purified with florisil. The purified samples wereanalyzed by HPLC-UVD and confirmed with LC-MS. Linear range was between 0.1~5 mg/kgwith thecorrelation coefficient (r 2 ) 0.99997. Average recoveries of imicyafos ranged from 77.0 to 115.4% at the spikedlevels of 0.02 and 0.05 mg/kg with the relative standard deviations of 2.2~9.6%. Limit of detection andquantification were 0.005 and 0.02 mg/kg, respectively. An inter-laboratory study was conducted to validatethe determination method in depth, and the results were satisfactory. All of the validation results revealed thatthe developed analytical method in this study is relevant for imicyafos determination in agricultural commoditiesand will be used as an official analytical method.요약: Imicyafos는 뿌리혹선충류, 뿌리선충류, 뿌리썩이선충류 등의 방제에 효과적인 살선충제로 국내에는 2012년에 처음 사용 등록되었으며, 식품의약품안전처에서 수박과 참외에 신규 잔류허용기준(0.05mg/kg)을 신설·고시하였다 . Imicyafos는 증기압이 1.9×10

Fenpyrazamine which is a pyrazole fungicide class for controlling gray mold, sclerotinia rot, and Monilinia in grapevines, stone fruit trees, and vegetables has been registered in republic of Korea in 2013 and the maximum residue limits of fenpyrazamine is set to grape, peach, and mandarin as 5.0, 2.0, and 2.0 mg/ kg, respectively. Very reliable and sensitive analytical method for determination of fenpyrazamine residues is required for ensuring the food safety in agricultural products. Fenpyrazamine residues in samples were extracted with acetonitrile, partitioned with dichloromethane, and then purified with silica-SPE cartridge and eluted with hexane and acetone mixture. The purified samples were determined by HPLC-UVD and confirmed with LC- MS and quantified using external standard method. Linear range of fenpyrazamine was between 0.1~5.0 µg/mL with the correlation coefficient (r) 0.999. The average recovery ranged from 71.8 to 102.7% at the spiked level of 0.05, 0.5, and 5.0 mg/kg, while the relative standard deviation was between 0.1 and 7.3%. In addition, limit of detection and limit of quantitation were 0.01 and 0.05 mg/L, respectively. The results revealed that the developed and validated analytical method is possible for fenpyrazamine determination in agricultural product samples and will be used as an official analytical method.

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

BACKGROUND: This study was conducted to develop analytical method with reproducibility, accuracy and applicability to agricultural products than the existing methods. METHODS AND RESULTS: Mean recoveries of thidiazuron ranged from 89.2 to 91.2 in hulled rices, 87.2 to 92.1 in peppers, from 76.4 to 86.9 in potatoes, from 91.2 to 95.7 in watermelons, from 86.5 to 88.5 in kiwi fruits, and from 89.5 to 94.0 in grapes, with less than 10% of relative standard deviations. In addition, the limit of quantitation was set to be 0.05 mg/kg and there were no interfering peaks in integrating the thidiazuron peak. CONCLUSION(S): These results represent that the enhanced analytical method has reliable accuracy, precision, selectivity, and sensitivity.

A simple and sensitive analytical method was developed using gas chromatograph with electroncapture detector (GC-ECD) and gas chromatograph-mass spectrometer (GC-MS) for determination and identificationof chloropicrin. Because of small molecular weight and high volatile properties of chloropicrin, analytical method wasdeveloped utilizing headspace extraction and direct injection to the GC. The developed method was validated usinghulled rice sample spiked with chloropicrin at different concentration levels, 0.1 and 0.5 mg/kg. Average recoveriesof chloropicrin (using each concentration three replicates) ranged 77.7~79.3% with relative standard deviations lessthan 10% and calibration solutions concentration in the range 0.005~0.5 µ g/mL, and limit of detection (LOD) andlimit of quantification (LOQ) were 0.004 and 0.01 mg/kg, respectively. The result showed that developed analyticalmethods was successfully applied to detect a small amount of chloropicrin in hulled rice.Key words: chloropicrin, headspace extraction, hulled rice, GC-ECD, GC-MS

Validated analytical methods for isopyrazam are meager or lacking. In the present study, a singleresidual analytical method was developed for isopyrazam in selected commodities. Isopyrazam was analyzedin brown rice, soybean, green pepper, mandarin, cucumber, and Korean melon. We tried different solventsand methods through extraction, partition and purification steps to obtain best analytical results. Forisopyrazam samples were extracted with acetonitrile, concentrated and partitioned with n-hexane, clean-upusing florisil with n-hexane/ethylacetate (70/30) and analyzed with HPLC/UVD. The limit of quantitation(LOQ) for isopyrazam was 1.0 ng (S/N > 10) and method LOQ (MLOQ) was 0.04 mg kg Š 1 . Recovery rangedthrough 81.0~105.3% (syn-isomer) and 80.8~105.6% (anti-isomer) at fortification level of 0.04 (MLOQ), 0.4(10 × MLOQ), and 2.0 (50 × MLOQ). The coefficient of variation (CV) for isopyrazam was less than 10%regardless of sample types. These results were further confirmed with LC/MS, respectively. The proposedmethod is highly reproducible and sensitive and is suitable for routine analysis.Key words Agricultural products, Isopyrazam, Limit of quantitation, Pesticide, Single residual analytical method

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.