• Preventive Nutrition and Food Science
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• v.18 no.2
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• pp.145-149
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• 2013

We tested for residual pesticide levels in dried vegetables in Seoul, Korea. A total of 100 samples of 13 different types of agricultural products were analyzed by a gas chromatography-nitrogen phosphate detector (GC-NPD), an electron capture detector (GC-${\mu}ECD$), a mass spectrometry detector (GC-MSD), and a high performance liquid chromatography- ultraviolet detector (HPLC-UV). We used multi-analysis methods to analyze for 253 different pesticide types. Among the selected agricultural products, residual pesticides were detected in 11 samples, of which 2 samples (2.0%) exceeded the Korea Maximum Residue limits (MRLs). We detected pesticide residue in 6 of 9 analyzed dried pepper leaves and 1 sample exceeded the Korea MRLs. Data obtained were then used for estimating the potential health risks associated with the exposures to these pesticides. The estimated daily intakes (EDIs) range from 0.1% of the acceptable daily intake (ADI) for bifenthrin to 8.4% of the ADI for cadusafos. The most critical commodity is cadusafos in chwinamul, contributing 8.4% to the hazard index (HI). This results show that the detected pesticides could not be considered a serious public health problem. Nevertheless, an investigation into continuous monitoring is recommended.

• Journal of Veterinary Clinics
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• v.27 no.5
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• pp.565-568
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• 2010

Sulfaquinoxaline (SQX) and trimethoprim (TMP) are chemotherapeutics that are extensively used in various animal species for the treatment or prevention of coccidia and coccidia-like parasites. Little information about the depletion kinetics of these compounds in chickens exists in the literature. In this study, a new commercial liquid concentrate of SQX in combination with TMP (100 g/l of SQX and 33.4 g/l of TMP) was administered with drinking water at a dose of 0.75 ml/l or 1.5 ml/l. The edible tissue concentrations of the drugs were determined by the validated high-performance liquid chromatography/mass spectrometric method. Residue concentrations of SQX and TMP were lower than their maximum residual limits (MRLs) in all tissues from both dose groups at 5 days after the treatment. The optimal withdrawal time of SQX/TMP combination was suggested to be over 5 days after cessation of medication in broilers.

• Toxicological Research
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• v.26 no.2
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• pp.149-155
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• 2010

The pesticide trichlorfon is readily degraded under experimental conditions to dichlorvos. A method has therefore been developed by which residues of trichlorfon in milk are determined as dichlorvos, using gas chromatography with ${\mu}$-electron capture detection. The identification of dichlorvos was confirmed by mass spectrometry. Milk was extracted with acetonitrile followed by centrifugation, freezing lipid filtration, and partitioning into dichloromethane. The residue after partitioning of dichloromethane was dissolved in ethyl acetate for gas chromatography. Recovery concentration was determined at 0.5, 1.0, and 2.0 of times the maximum permitted residue limits (MRLs) for trichlorfon in milk. The average recoveries (n = 6) ranged from 92.4 to 103.6%. The repeatability of the measurements was expressed as relative standard deviations (RSDs) ranging from 3.6%, to 6.7%. Limit of detection (LOD) and limit of quantification (LOQ) were 3.7 and $11.1{\mu}g/l$, respectively. The accuracy and precision (expressed as RSD) were estimated at concentrations from 25 to $250{\mu}g/l$. The intra- and inter-day accuracy (n = 6) ranged from 89.2% to 91% and 91.3% to 96.3%, respectively. The intra- and inter-day precisions were lower than 8%. The developed method was applied to determine trichlorfon in real samples collected from the seven major cities in the Republic of Korea. No residual trichlorfon was detected in any samples.

• Korean Journal of Veterinary Research
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• v.62 no.2
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• pp.18.1-18.8
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• 2022

This study investigated dexamethasone (DXM) residues in the milk from intramuscularly dosed dairy cows and established the withdrawal time (WT) of DXM in milk. Eighteen healthy Holstein cows were injected with 20 (DXM-1) or 40 mL (DXM-2) of a drug containing 1 mg/mL of DXM. After administering DXM, milk samples were collected from all cows at 12-hour intervals for five days. The DXM residue concentrations in milk were determined by liquid chromatography-tandem mass spectrometry. The correlation coefficient of the calibration curve was 0.9966, and the limits of detection and quantification (LOQ) were 0.03 and 0.1 ㎍/kg, respectively. The recoveries were 97.0% to 104.0%, and the coefficient of variations was less than 7.22%. After treatment, DXM in DXM-1 was detected above the LOQ in two milk samples at 36 hours and below the LOQ in all milk samples of DXM-2 at 48 hours. Using the WT calculation program WT 1.4, the withdrawal periods of DXM-1 and DXM-2 in milk were established to be two days. In conclusion, the developed analytical method is sensitive and reliable for detecting DXM in milk. The estimated WT of DXM in bovine milk is shorter than the current milk WT recommendation of three days for DXM in lactating dairy cows.

• Food Science of Animal Resources
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• v.43 no.5
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• pp.914-937
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• 2023

The objective of this study was to establish a multi-residue quantitative method for the analysis of anthelmintic and antiprotozoal drugs in various livestock products (beef, pork, and chicken) using ultra-high-performance liquid chromatography-tandem mass spectrometry. Each compound performed validation at three different levels i.e., 0.5, 1, and 2× the maximum residue limit according to the CODEX guidelines (CAC/GL 71-2009). This study was conducted according to the modified quick, easy, cheap, effective, rugged, and safe procedure. The matrix-matched calibrations gave correlation coefficients >0.98, and the obtained recoveries were in the range of 60.2%-119.9%, with coefficients of variation ≤32.0%. Furthermore, the detection and quantification limits of the method were in the ranges of 0.03-3.2 and 0.1-9.7 ㎍/kg, respectively. Moreover, a survey of residual anthelmintic and antiprotozoal drugs was also carried out in 30 samples of beef, pork, and chicken collected in Korea. Toltrazuril sulfone was detected in all three samples. Thus, our results indicated that the developed method is suitable for determining the anthelmintic and antiprotozoal drug contents in livestock products.

• Toxicological Research
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• v.24 no.3
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• pp.207-212
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• 2008

Pesticide residues play several key roles as environmental and food pollutants and it is crucial to develop a method for the rapid determination of pesticide residues in environments. In this study, a simple, effective, and sensitive method has been developed for the quantitative analysis of methoxyfenozide in water and soil when kept under laboratory conditions. The content of methoxyfenozide in water and soil was analyzed by first purifying the compound through liquid-liquid extraction and partitioning followed by florisil gel filtration. Upon the completion of the purification step the residual levels were monitored through high performance liquid chromatography(HPLC) using a UV absorbance detector. The average recoveries of methoxyfenozide from three replicates spiked at two different concentrations and were ranged from 83.5% to 110.3% and from 98.1% to 102.8% in water and soil, respectively. The limits of detection(LODs) and limits of quantitation(LOQs) were 0.004 vs. 0.012 ppm and 0.008 vs. 0.024 ppm, respectively. The method was successfully applied to evaluate the behavioral fate of a 21% wettable powder(WP) methoxyfenozide throughout the course of 14 days. A first-order model was found to accurately fit the dissipation of methoxyfenozide in water with and a $DT_{50}$ value of 3.03 days was calculated from the fit. This result indicates that methoxyfenozide dissipates rapidly and does not accumulate in water.

• Korean Journal of Veterinary Service
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• v.34 no.4
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• pp.429-439
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• 2011

This article described the comparison of a quick, easy, cheap, effective, rugged and safe (QuEChERS) sample preparation and the classical method established by National Veterinary Research and Quarantine Service (NVRQS) for the determination of pesticide residues in livestock products using GC-tandem mass spectrometry. The classical method by NVRQS used liquid-liquid partioning followed by evaporizing. The modified QuEChERS entailed extraction of 2 g sample with 15 ml acetonitrile containing 1% acetic acid followed by addition of 6 g anhydrous magnesium sulfate and 1.5 g sodium acetate. After centrifugation, 6 ml of the extract underwent a cleanup step (in a technique known as column-based solid phase extraction) using 400 mg each of $C_{18}$ and primary secondary amine sorbents plus 1,200 mg magnesium sulfate. The quantitation of individual pesticides by both methods was based on tissue standard calibration curves with a correlation coefficient in excess of 0.98 for the 24 pesticides. The detection limits by the classical method were ranged 1.3~5.0 ${\mu}g$/kg, with mean recoveries between 76.2% and 114.3% except aldrin (59.3%) and deltamethrin (63.6%). The detection limits by modified QuEChERS were ranged 0.3~6.2 ${\mu}g$/kg, with mean recoveries between 68.0% and 114.3% except dimethipin (152.6%), chlorfenvinphos (138.1%), 4,4-DDT (61.5%), aldrin (60.4%) and chinomethionate (30.3%).

• Korean Journal of Veterinary Research
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• v.63 no.3
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• pp.23.1-23.9
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• 2023

This study was conducted to investigate tiamulin (TML) residues in the edible tissues of orally dosed broiler chickens and to re-establish the withdrawal time (WT). Thirty-six healthy Ross broiler chickens were administered 0.5 (TML-1) and 2.5 kg (TML-2) per ton feed, respectively, of the drug containing TML 78 g/kg for 10 days. Twenty-four tissue samples were collected from 6 chickens in each of the TML-1 and TML-2 groups on 0, 1, 3, and 5 days after drug administration, respectively. The residual concentrations of TML were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The correlation coefficient of the calibration curves was 0.9978 to 0.9998, and the limits of detection and the limits of quantification (LOQ) were in the range of 0.03 to 0.06, and 0.1 to 0.2 ㎍/kg, respectively. Recoveries ranged between 89.0% to 116.7%, and the coefficients of variation were less than 13.9%. After the drug administration, TML in the TML-1 and TML-2 groups was detected above the LOQ in 1 and 6 samples of liver, respectively, at day 0, and in 1 liver sample from both groups on day one. At 3 days after administration, TML was detected below the LOQ in all samples of TML-1 and TML-2. The calculated WT of TML in both TML-1 and TML-2 using the WT calculation program WT 1.4 was 0 days. In conclusion, the developed analytical method is suitable for detection, and the calculated WT of TML in poultry edible tissues is shorter than the current recommended WT of 7 days for TML in broiler chickens.

• Analytical Science and Technology
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• v.28 no.3
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• pp.175-181
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• 2015

Cyantraniliprole, which is an ananthranilic diamide insecticide that was developed by the DuPont Corporation, was registered in the Republic of Korea in 2012. It offers exceptional insecticidal activity on a broad range of Lepidopera, Coleoptera, Diptera, and Isoptera. The maximum residue limits are set to pepper, peach, apple, sweet pepper, welsh onion, and so on (0.2~2.0 mg/kg). Therefore, an analytical method for determining cyantraniliprole residue in agricultural products was developed to ensure food safety. In previous studies, welsh onions were among vegetables included in the allium species, which is a representative plant with sulfur organic compounds. In this study, the analytical method was developed and evaluated for the elimination of sulfur compounds from the test solution of allium species during pesticide residue analysis. In order to inactivate the enzyme allinase and produce sulfur compounds, sample extraction was made in the base state pH 10 by reducing the activity of the enzyme. The recoveries of the developed method ranged from 81.9% to 83.2%, and the relative standard deviations were less than 10%. Therefore, based on the results, the method developed in this study is accurate and appropriate for use in cyantraniliprole determination. It will be used as the official method for managing the safety of cyantraniliprole residues in agricultural products.

• The Korean Journal of Pesticide Science
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• v.17 no.4
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• pp.271-282
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• 2013

This is the result of pesticide residue monitoring certified Good Agricultural Practice (GAP) by national agricultural cooperative federation (NACF) from 2009 to 2012. NACF evaluated simultaneously 283 pesticide multi-analysis method with GC (ECD, NPD) and HPLC. 6,590 agricultural products were analyzed in this period. As the results 1) detected 20.27% in 2009, 23.42% in 2010, 28.07% in 2011 and finally 31.75% in 2012, respectively. There was the total detected pesticide residue in the agricultural products. The violated ratio of agricultural products were 2.25% in 2009, 1.82% in 2010, 1.67% in 2011 and 3.47% in 2012, respectively. 13 pesticides went over the maximum residue limits (MRLs); carbendazim was the predominant violation. 40 pesticides; endosulfan was the predominant detected pesticide did not registered respectively crops in Korea. Most agricultural products that were under the MRLs met the safety standard, however agricultural products that contain neither registered nor set up MRL any level for example endosulfan in strawberry. Agricultural products that go over the MRLs with permitted pesticides, for example carbendazim in apple, are rejected. Because of these intricacies continual observation and evaluation will be need during GAP agricultural cultivation.