• Food Science of Animal Resources
• /
• v.38 no.5
• /
• pp.1055-1063
• /
• 2018

The aim of study was to investigate the correlation between the level of 17 antibiotic residues and 6 antibiotic resistances of Escherichia coli isolates in chicken meats. A total of 58 chicken meats were collected from retail grocery stores in five provinces in Korea. The total detection rate of antibiotic residues was 45% (26 out of 58). Ten out of 17 antibiotics were detected in chicken meats. None of the antibiotics exceeded the maximum residue level (MRLs) in chicken established by the Ministry of Food and Drug Safety (MFDS). The most detected antibiotics were amoxicillin (15.5%), followed by enrofloxacin (12.1%) and sulfamethoxazole (10.3%). In a total of 58 chicken meats, 51 E. coli strains were isolated. E. coli isolates showed the highest resistance to ampicillin (75%), followed by tetracycline (69%), ciprofloxacin (65%), trimethoprim/sulfamethoxazole (41%), ceftiofur (22%), and amoxicillin/clavulanic acid (12%). The results of study showed basic information on relationship between antibiotic residue and resistance for 6 compounds in 13 chicken samples. Further investigation on the antibiotic resistance patterns of various bacteria species is needed to improve food safety.

• Korean Journal of Environmental Agriculture
• /
• v.39 no.3
• /
• pp.246-252
• /
• 2020

BACKGROUND: Pesticides are broadly used to control weeds and pests, and the residues remaining in crops are managed in accordance with the MRLs (maximum residue limits). Therefore, an analytical method is required to quantify the residues, and we conducted a series of analyses to select and validate the quick and simple analytical method for tolpyralate in five agricultural products using QuEChERS (quick, easy, cheap, effective, rugged and safe) method and LC-MS/MS (liquid chromatography-tandem mass spectrometry). METHODS AND RESULTS: The agricultural samples were extracted with acetonitrile followed by addition of anhydrous magnesium sulfate, sodium chloride, disodium hydrogencitrate sesquihydrate and trisodium citrate dihydrate. After shaking and centrifugation, purification was performed with d-SPE (dispersive-solid phase extraction) sorbents. To validate the optimized method, its selectivity, linearity, LOD (limit of detection), LOQ (limit of quantitation), accuracy, repeatability, and reproducibility from the inter-laboratory analyses were considered. LOQ of the analytical method was 0.01 mg/kg at five agricultural products and the linearity of matrix-matched calibration were good at seven concentration levels, from 0.0025 to 0.25 mg/L (R²≥0.9980). Mean recoveries at three spiking levels (n=5) were in the range of 85.2~112.4% with associated relative standard deviation values less than 6.2%, and the coefficient of variation between the two laboratories was also below 13%. All optimized results were validated according to the criteria ranges requested in the Codex Alimentarius Commission (CAC) and Ministry of Food and Drug Safety (MFDS) guidelines. CONCLUSION: In conclusion, we suggest that the selected and validated method could serve as a basic data for detecting tolpyralate residue in imported and domestic agricultural products.

• Asian-Australasian Journal of Animal Sciences
• /
• v.14 no.3
• /
• pp.378-381
• /
• 2001

Sulfamethazine has been widely used in swine for prevention or treatment of infections. Recently, the safety of the drug to consumers has been questioned because of carcinogenic effects. To prevent unwanted drug residues entering the human food chain, both government authorities and industries have established extensive control measures. The demands for reliable, simple, sensitive, rapid and low-cost methods for residue analysis of foods are increasing nowadays. In this study, we established a rapid prediction test for the detection of cattle with violative tissue residues of sulfamethazine. The recommended therapeutic dose of sulfamethazine (withdrawal time, 15 days) was administered to each of 10 cattle. Blood was sampled before drug administration and during the withdrawal period. The concentration of sulfamethazine in plasma, determined by a semi-quantitative ELISA, was compared to that of an internal standard (10 ppb). The absorbance ratio of internal standard to sample (B/Bs) was employed as an index to determine whether drug residues in cattle tissues were negative or positive. That is, a B/Bs ratio less than 1 was considered residue positive and if larger than 1 was considered negative. All 10 plasma samples from non-treated cattle showed negative to sulfamethazine. Sulfamethazine was detected in plasmas of treated cattle until Day 7 of withdrawal period. The present study showed that the semi-quantitative ELISA could be easily adapted in predicting residues of sulfamethazine in live cattle.

• Korean Journal of Environmental Agriculture
• /
• v.41 no.4
• /
• pp.288-309
• /
• 2022

BACKGROUND: The objective of this study was to develop a comprehensive and simple method for the simultaneous determination of 59 veterinary drug residues in livestock products for safety management. METHODS AND RESULTS: For sample preparation, we used a modified liquid extraction method, according to which the sample was extracted with 80% acetonitrile followed by incubation at -20℃ for 30 min. After centrifugation, an aliquot of the extract was evaporated to dryness at 40℃ and analyzed using liquid chromatography combined with tandem mass spectrometry. The method was validated at three concentration levels for beef, pork, chicken, egg, and milk in accordance with the Codex Alimentarius Commission/Guidelines 71-2009. Quantitative analysis was performed using a matrix-matched calibration. As a results, at least 52 (77.6%) out of 66 compounds showed the proper method validation results in terms of both recovery of the target compound and coefficient of variation required by Codex guidelines in livestock products. The limit of quantitation of the method ranged from 0.2 to 1119.6 ng g-1 for all matrices. CONCLUSION(S): This method was accurate, effective, and comprehensive for 59 veterinary drugs determination in livestock products, and can be used to investigate veterinary drugs from different chemical families for safety management in livestock products.

• Korean Journal of Environmental Agriculture
• /
• v.34 no.3
• /
• pp.230-237
• /
• 2015

BACKGROUND: To identify the sources of inaccuracy in LC/MS/MS methods used in the routine quantitation of small molecules are described and discussed. METHODS AND RESULTS: Various UPLC coupled to triple quadrupole mass spectrometer and time of flight (TOF) were used to identify the potential sources of inaccuracy and inducing the pitfalls of qualification and quntitation during the veterinary drug residue analysis. Some of stable isotope labelled veterinary drugs, which were used as internal standards, presented "cross-talk", regardless of manufactures of mass spectrometer and types of spectrometer. Group of sulfonamides also presented inaccuracy qualification and quantitation due to the multi-residue analytical method with the same fragment ions at the close retention times. CONCLUSION: The phenomena of "cross-talk" occurring between subsequently monitored transition from stable isotope labelled and isotope non-labelled authentic chemical were identified. To prevent errors and achieve more accurate data during the analysis of small molecules by LC/MS/MS SRM method, Followings should be taken care of and kept checking; purity and concentration of stable isotope as an internal standard, prevention of carry-over during the separation in column, minimizing the ion suppression by matrix effect, identification of retention time, precursor ion and product ion, and full knowledge of data processing including smoothing and peak integration.

• Journal of Food Hygiene and Safety
• /
• v.35 no.2
• /
• pp.109-117
• /
• 2020

This study aimed to develop an analytical method for determination of 18 dyes in livestock and fishery products by liquid chromatograph-tandem mass spectrometry (LC-MS/MS). The developed method was validated for linearity, accuracy, limit of quantifications (LOQ) and recovery based on the CODEX guideline (CAC/GL-71). Target matrices (beef, pork, chicken, egg, milk, flatfish, eel, and shrimp) were extracted using acetonitrile (containing 1% of acetic acid) and then, purified with C₁₈ and primary secondary amine (PSA). Calibration linearity was obtained (r²>0.98) and LOQs were 0.002 mg/kg in animal products. The recoveries of dyes were ranged from 63 to 112% and relative standard deviations (RSDs, %) were less than 15%. The residues of 18 dyes were investigated in real samples (n=124) collected from retail markets in South Korea. As a result, a total of seven samples showed positive results for target analytes in fish samples. However, there was no violation according to the maximum residue limits set by the Korean Food Code. The proposed method will be used for routine analysis of dye residues in livestock and fishery products.

• Korean Journal of Veterinary Research
• /
• v.39 no.6
• /
• pp.1180-1186
• /
• 1999

The 102 farms received a positive result of the bulk milk drug residue test were selected to investigate the reasons of drug residues in bulls milk. The most frequent causes of drug residues were milker or producer mistakes (28.4%), failure to observe withdrawal time (21.5%), and withholding milk from treated quarters only (19.6%). Milker or producer mistakes occurred high at the farms having a parlor system (4 cases out of 11 farms), and related to the inadequate records and marking of treated cows. The lack of knowledge on the absorption of antibiotic from treated quarters and its excretion from untreated quarters caused mainly withholding milk from treated quarters only. Among the 91 farms identified the cause of drug residues, most of the route of drug administration was intramammary infusion (81.3%), and mostly drug used for the treatment of cows was ${\beta}$-lactam antibiotic (57.1%)

• Analytical Science and Technology
• /
• v.34 no.1
• /
• pp.1-8
• /
• 2021

An analytical method was developed and optimized for the quantification of a plant growth regulator, 2,6-diisopropylnaphthalene (2,6-DIPN), in agricultural products using gas chromatography-tandem mass spectrometry. The samples were extracted, partitioned, and were purified using a Florisil® cartridge. To validate the analytical method, its specificity, linearity, limit of detection (LOD) and limit of quantification (LOQ) of the instrument, LOQ of the analytical method (MLOQ), accuracy, and repeatability were considered. The method displayed excellent results during validation, and is suitable for the determination and quantification of the low residual levels of the analyte in the agricultural samples. All of the results with the optimized method were satisfactory and within the criteria ranges requested in the Codex Alimentarius Commission guidelines and the Ministry of Food and Drug Safety guidelines for pesticide residue analysis. The developed method is simple and accurate and can be used as a basis for safety management of 2,6-DIPN.

• Korean Journal of Environmental Agriculture
• /
• v.41 no.4
• /
• pp.261-275
• /
• 2022

BACKGROUND: Prior to implementing a positive list system (PLS), there is a need to establish acceptable daily intake (ADI) and maximum residue limit (MRL) for veterinary drugs that have been approved a few decades ago in South Korea. On top of that, chronic dietary exposure assessment of veterinary drug residues should be performed to determine whether the use of these veterinary drugs would cause health concerns or not. METHODS AND RESULTS: To establish the ADI, the relevant toxicological data were collected from evaluation reports issued by international organizations. A slightly modified global estimate of chronic dietary exposure (GECDE) model was employed in the exposure assessment owing to the limited residual data. Therefore, only the ADI of ephedrine was established due to insufficient data for the other veterinary drugs. Thus, instead of ADI, the threshold of toxicological concern (TTC) value was used for the other drugs. Lastly, the hazard index (HI) was calculated, except for etizazole hydrochloride, due to the potential of mutagenicity. CONCLUSION(S): The HI values of ephedrine, menichlopholan, and anacolin were found to be as high as 6.4%, suggesting that chronic dietary exposure to the residues from these uses was unlikely to be a public health concern. Further research for exposure assessment of veterinary drug residues should be performed using up-todate Korean national health and nutrition examination survey (KNHANES) food consumption data. In addition, all relevant available data sources should be utilized for identifying the potentials of toxicity.

• Journal of Food Hygiene and Safety
• /
• v.38 no.3
• /
• pp.131-139
• /
• 2023

In this study, we investigated pesticide residue levels in 535 domestically distributed agricultural products in South Korea using multi-residue analysis. Agricultural products from 13 regions, including Seoul, were pretreated using QuEChERS and d-SPE, and subsequently analyzed using LC-MS/MS and GC-MS/MS. Residual pesticides were detected in 288 (53.8%) out of the 535 samples, including 40 of apples, 40 of peppers, 33 of mandarins, 31 of peaches, and 144 other commodities. Furthermore, one sample of Korean cabbage exceeded the permitted maximum residue limit (MRL), diniconazole (0.18 mg/kg), detected at about twice the MRL. In total, 91 types of residual pesticides were detected, including fungicides (42), insecticides (48), and a nematicide. The most frequently detected pesticides were dinotefuran (91), carbendazim (75), tebuconazole (61), and pyraclostrobin (59). Our results showed that continuous monitoring of agricultural products is necessary.