• Korean Journal of Food Science and Technology
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• v.45 no.3
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• pp.285-292
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• 2013

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.

• Journal of Food Hygiene and Safety
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• v.34 no.1
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• pp.30-39
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• 2019

An analytical method was developed for the determination of sedaxane in agricultural products using liquid chromatograph-tandem mass spectrometry (LC-MS/MS). The samples were extracted with acetonitrile and partitioned with dichloromethane to remove the interference, and then purified by using silica SPE cartridges to clean up. The analytes were quantified and confirmed by using LC-MS/MS in positive ion mode using multiple reaction monitoring (MRM). The matrix-matched calibration curves were linear over the calibration ranges ($0.001-0.25{\mu}g/mL$) into a blank extract with $r^2$>0.99. For validation, recovery tests were carried out at three different concentration levels (LOQ, 10LOQ, and 50LOQ, n=5) with five replicates performed at each level. The recoveries were ranged between 74.5 to 100.8% with relative standard deviations (RSDs) of less than 12.1% for all analytes. All values were consistent with the criteria ranges requested in the Codex guidelines (CAC/GL 40, 2003) and Food Safety Evaluation Department guidelines (2016). The proposed analytical method was accurate, effective and sensitive for sedaxane determination in agricultural commodities.

• Korean Journal of Materials Research
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• v.13 no.9
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• pp.572-580
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• 2003

Synthesizing behavior and microstructural evolution of $CaZrO_3$and $m-ZrO_2$in a thermal reaction process of $ZrSiO_4$-$xCaCO_3$mixtures, where x is 7 and 19, were investigated to determine the addition amount of CaO in CaO:$ZrO_2$:$SiO_2$ternary composition. CaZrO$_3$-Ca$_2$SiO$_4$precursor prepared by the mixture of $ZrSiO_4$and CaCO$_3$in aqueous suspending media was controlled to the acidic (pH=4.0) condition with HCI solution to enhance the thermal reaction. The addition amount of dispersant into the $ZrSiO_4$-$xCaCO_3$slip increased with increasing mole ratio of $CaCO_3$, which was associated with the viscosity of slip. Decarbonation reaction was activated with an increase of the addition amount of $CaCO_3$, showing different final temperatures in $ZrSiO_4$-$7CaCO_3$and $ZrSiO_4$-$19CaCO_3$mixtures as about 980 and 116$0^{\circ}C$, respectively, for finishing decarbonation reaction. The grain morphology was changed to spherical shape for all samples with an increase of sintering temperature. The grain size and phase composition of the synthesized composites depended on the mixture ratio of Zrsi04 and CacO3 powders, indicating that the main crystals were m-ZrO2 ($\leq$3 $\mu\textrm{m}$) and $CaZrO_3$ ($\leq$ 7 $\mu\textrm{m}$) in $ZrSiO_4$$>-7CaCO_3$and $ZrSiO_4$-$19CaCO_3$mixtures, respectively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.3
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• pp.277-284
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• 2012

In this study, a heat-transfer performance analysis is carried out for a multi-channel volumetric air receiver for a solar power tower. On the basis of a series of reviews regarding the relevant literature, a calculation process is proposed for the prediction of the wall- and air- temperature distributions of a single channel at given geometric and input conditions. Furthermore, a unique mathematical model of the receiver effectiveness is presented through analysis of the temperature profile. The receiver is made of silicon carbide. A total of 225 square straight channels per module are molded to induce the air flow, and each channel has the dimensions of $2mm(W){\times}2mm(H){\times}0.2mm(t){\times}320mm(L)$. The heat-transfer rate, temperature distribution and effectiveness are presented according to the variation of the channel and module number under uniform irradiation and mass flow rate. The available air outlet temperature applied to the solar power tower should be over $700^{\circ}C$. This numerical model was actually used in the design of a 200 kW-level commercial solar air receiver, and the required number of modules satisfying the thermal performance could be obtained for the specified geometric and input conditions.

• Journal of Food Hygiene and Safety
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• v.31 no.6
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• pp.432-438
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• 2016

Ethoxyquin (EQ, 1,2-dihydro-6-ethoxy-2,2,4-trimethyl-quinoline) is quinoline-based antioxidant used in the animal feed and food industry to protect the raw materials and final products against oxidation. In recent years the use of synthetic antioxidants in fishmeal ingredients carry-over to farmed fish fillets has received increasing attention in food safety. This study was conducted to develop an analytical method to determine EQ in aquatic products. The analytes were confirmed and quantified via liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the positive ion mode using multiple reaction monitoring (MRM). The sample was extracted with 1 N HCl (in case of flatfish extracted with 1 N HCl containing 10% acetonitrile). Then, solid phase extraction (SPE) was used for the cleanup. Standard calibration curves presented linearity with the correlation coefficient ($r^2$) > 0.99, analyzed at 0.005-0.2 mg/kg concentration. The developed method was validated according to the Codex Alimentarius Commission (CAC) guideline. The limits of quantitation for EQ were 0.01 mg/kg. Average recoveries ranged from 81.3% to 107%. The repeatability of measurements, expressed as the coefficient of variation (CV, %), was below 10%. The analytical method was characterized with high accuracy and acceptable sensitivity to meet CODEX guideline requirements and would be applicable to analyze the EQ residue in aquatic products.

• Journal of Food Hygiene and Safety
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• v.32 no.4
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• pp.298-305
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• 2017

Benzovindiflupyr is a new pyrazole carboxamide fungicide that inhibits succinate dehydrogenase of mitochondrial respiratory chain. This study was carried out to develop an analytical method for the determination of benzovindiflupyr residues in agricultural commodities using LC-MS/MS. The benzovindiflupyr residues in samples were extracted by using acetonitrile, partitioned with dichloromethane, and then purified with silica solid phase extraction (SPE) cartridge. Correlation coefficient ($r^2$) of benzovindiflupyr standard solution was 0.99 over the calibration ranges ($0.001{\sim}0.5{\mu}g/mL$). Recovery tests were conducted on 5 representative agricultural commodities (mandarin, green pepper, potato, soybean, and hulled rice) to validate the analytical method. The recoveries ranged from 79.3% to 110.0% and then relative standard deviation (RSD) was less than 9.1%. Also the limit of detection (LOD) and limit of quantification (LOQ) were 0.0005 and 0.005 mg/kg, respectively. The recoveries of interlaboratory validation ranged from 83.4% to 117.3% and the coefficient of variation (CV) was 9.0%. All results were followed with Codex guideline (CAC/GL 40) and Ministry of Food and Safety guideline (MFDS, 2016). The proposed new analytical method proved to be accurate, effective, and sensitive for benzovindiflupyr determination and would be used as an official analytical method.

• Journal of Food Hygiene and Safety
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• v.38 no.5
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• pp.361-372
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• 2023

Organotin pesticide is used as an acaricide in agriculture and may contaminate livestock products. This study aims to develop a rapid and straightforward analytical method for detecting organotin pesticides, specifically azocyclotin, cyhexatin, and fenbutatin oxide, in various livestock products, including beef, pork, chicken, egg, and milk, using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The extraction process involved the use of 1% acetic acid in a mixture of acetonitrile and ethyl acetate (1:1). This was followed by the addition of anhydrous magnesium sulfate (MgSO₄) and anhydrous sodium chloride. The extracts were subsequently purified using octadecyl (C₁₈) and primary secondary amine (PSA), after which the supernatant was evaporated. Organotin pesticide recovery ranged from 75.7 to 115.3%, with a coefficient of variation (CV) below 25.3%. The results meet the criteria range of the Codex guidelines (CODEX CAC/GL 40). The analytical method in this study will be invaluable for the analysis of organotin pesticides in livestock products.

• Journal of Food Hygiene and Safety
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• v.34 no.3
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• pp.227-234
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• 2019

An analytical method was developed for the determination of oxytetracycline in agricultural products using the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method by liquid chromatography-tandem mass spectrometry (LC-MS/MS). After the samples were extracted with methanol, the extracts were adjusted to pH 4 by formic acid and sodium chloride was added to remove water. Dispersive solid phase extraction (d-SPE) cleanup was carried out using $MgSO_4$ (anhydrous magnesium sulfate), PSA (primary secondary amine), $C_{18}$ (octadecyl) and GCB (graphitized carbon black). The analytes were quantified and confirmed with LC-MS/MS using ESI (electrospray ionization) in positive ion MRM (multiple reaction monitoring) mode. The matrix-matched calibration curves were constructed using six levels ($0.001{\sim}0.25{\mu}g/mL$) and coefficient of determination ($r^2$) was above 0.99. Recovery results at three concentrations (LOQ, $10{\times}LOQ$, and $50{\times}LOQ$, n=5) were from 80.0 to 108.2% with relative standard deviations (RSDs) less than of 11.4%. For inter-laboratory validation, the average recovery was in the range of 83.5~103.2% and the coefficient of variation (CV) was below 14.1%. All results satisfied the criteria ranges requested in the Codex guidelines (CAC/GL 40-1993, 2003) and the Food Safety Evaluation Department guidelines (2016). The proposed analytical method was accurate, effective and sensitive for oxytetracycline determination in agricultural commodities. This study could be useful for safety management of oxytetracycline residues in agricultural products.

• Journal of Food Hygiene and Safety
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• v.33 no.2
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• pp.110-117
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• 2018

The aim of this study was to develop an analytical method for the quantification of diazepam residues in fishery products, using liquid and gas chromatography-tandem mass spectrometry (LC-MS/MS and GC-MS/MS). The sample utilized in the study was extracted from the fish sample (crucian carp) using 0.1% formic acid in acetonitrile. For the utilization of the purification process, the dispersive solid phase extraction (dSPE) was used for LC-MS/MS, dSPE and SPE was used for GC-MS/MS, respectively. To be sure, the standard calibration curves showed a good linearity as the noted correlation coefficients, $r^2$ was > 0.99. The average recoveries for accuracy ranged in 99.8~124% for the samples which were fortified at three different levels (0.001, 0.002 and 0.010 mg/kg). The correlation coefficient for the precision effect was measured at a range of 4.01~11.8%. The limit of detection (LOD) for the diazepam analysis was 0.0004 mg/kg, and the limit of the quantification (LOQ) was 0.001 mg/kg. The proposed analytical method was characterized with a high accuracy and acceptable sensitivity to meet the established Codex Alimentarius Commission (CAC/GL71-2009) guideline requirements. We therefore established the optimal analysis method for the determination of diazepam in the fishery products using LC-MS/MS and GC-MS/MS. It would be applicable to analyze the diazepam residues in fishery products in further studies on this subject.

• Journal of Food Hygiene and Safety
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• v.34 no.2
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• pp.124-134
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• 2019

An analytical method was developed for the determination of broflanilide and its metabolites in agricultural products. Sample preparation was conducted using the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method and LC-MS/MS (liquid chromatograph-tandem mass spectrometer). The analytes were extracted with acetonitrile and cleaned up using d-SPE (dispersive solid phase extraction) sorbents such as anhydrous magnesium sulfate, primary secondary amine (PSA) and octadecyl ($C_{18}$). The limit of detection (LOD) and quantification (LOQ) were 0.004 and 0.01 mg/kg, respectively. The recovery results for broflanilide, DM-8007 and S(PFP-OH)-8007 ranged between 90.7 to 113.7%, 88.2 to 109.7% and 79.8 to 97.8% at different concentration levels (LOQ, 10LOQ, 50LOQ) with relative standard deviation (RSD) less than 8.8%. The inter-laboratory study recovery results for broflanilide and DM-8007 and S (PFP-OH)-8007 ranged between 86.3 to 109.1%, 87.8 to 109.7% and 78.8 to 102.1%, and RSD values were also below 21%. All values were consistent with the criteria ranges requested in the Codex guidelines (CAC/GL 40-1993, 2003) and the Food and Drug Safety Evaluation guidelines (2016). Therefore, the proposed analytical method was accurate, effective and sensitive for broflanilide determination in agricultural commodities.