The Animal and Plant Quarantine Agency conducts a targeted sampling plan and analysis for veterinary drugs within the country every year. Target compounds included tetrachlorvinphos as an organophosphate, diminazene as an anti-infective medication, ketoprofen as a nonsteroidal anti-inflammatory drug, triclabendazole and clorsulon as flukicides in 2022. These compounds were not included in National Residues Program (NRP), despite their high sales ranking. A total of 94 bovine muscle samples and 20 equine muscle samples were collected from various locations across the country. The analysis of target compounds in muscle was performed using LC-MS/MS coupled with Food code 8.3.1 revised in 2022. A 2 g sample of muscle tissue was extracted using a water: acetonitrile (1:4, v/v) solution, then cleaned up with C18 and hexane saturated with acetonitrile. Compounds were separated with C18 column and mobile phases consisted of 0.1% formic acid in water (A) and 0.1% formic acid in acetonitrile (B). All analytes exhibited good linearity with correlation coefficients (R2) higher than 0.992. The limit of quantification (LOQ) of these compounds ranged from 0.21 to 2.79 μg/kg except for diminazene (3.85~6.86 μg/kg). The average recoveries of these analytes were 89.45~129.13% in muscle at spiked level of 10 or 20 μg/kg. Relative standard deviations (%) (intra-day and inter-day) were lower than 20% for all target compounds, except for diminazene and triclabendazole, whose intra-day RSD % was slightly higher than 20% in equine muscle. Testing confirmed that all 94 bovine and 20 equine muscle samples from 9 provinces were free from residues of veterinary drugs. Monitoring of compounds not included in the NRP should continue to ensure consumer health and food safety.

A simple and fast analytical method based on liquid chromatography-tandem mass spectrometry was developed for detection of the veterinary drugs acetanilide, anthranilic acid, antipyrine, cyproheptadine, diphenhydramine, DLmethylephedrine, and phenacetin in bovine milk. The target analytes were extracted from milk samples by using acetonitrile followed by clean-up with C18 and liquid-liquid purification with saturated n-hexane. A reverse-phase analytical column was employed with a mobile phase comprising (A) 0.1% formic acid in distilled water and (B) 0.1% formic acid in acetonitrile to achieve the best chromatographic separation. Matrix-matched calibration curves (r2 ≥ 0.9986) were constructed using six concentrations (1, 2, 5, 10, 20, and 40 μg/kg) of drugs in the milk matrix. Recoveries at three drug-spiking levels (5, 10, and 20 μg/kg) ranged from 71.2% to 103.8% with intra-day and inter-day relative standard deviation (RSD) values of ≤ 8.6%. The calculated limits of quantification (LOQ) were 0.19-7.1 μg/kg.

In this study, we described a suitable prioritisation scheme on these exempted drugs and established fundamental rules for residue monitoring enforcement in Korea. The principles of exempted materials were established. Based on these established criteria, 75 materials with high priority were selected and grouped. Among these materials, we have decided that 25 substances required further review for monitoring. Important factors for determining the priority for monitoring, product factor during the recent 4 years, veterinary medicine factors, including applied symptoms and component conditions, animal factors, including applied animals, and toxicological factors including acceptable daily intake (ADI), establishment of residual quantity permitted (MRL) or withdrawal periods, various provisory clauses and so on were set. High priority substances were acethylsalicylic acid, bromhexine, chlorpheniramine, and acetaminophen. In addition, we surveyed and provided analysis on the above mentioned materials in this study. The derived results will be suggested to the Animal and Plant Quarantine Agency (QIA) for development of guidelines of policy direction and the effective targeting for their monitoring program.

The Korean National Residue Program (KNRP) use three plans for the sampling of domestic meats: monitoring, surveillance, and exploratory testing. We analyzed the results of monitoring and surveillance for residual veterinary drugs and pesticides in meat during 2012 and 2013. KNRP targets food-producing animals including cattle, pigs, chickens, ducks, sheep (goats), and horses. Sampling mainly focuses on veterinary drugs and pesticide residues found in tissues such as muscle, kidney, and liver. A total of 548 residue violations occurred between 2012 and 2013, mainly in pigs (427 violations) and cattle (113 violations). The most commonly found compounds were antimicrobials such as penicillins, fluoroquinolones, aminoglycosides, tetracyclines, sulfonamides, and macrolides. Pig residue violations were mainly for the presence of penicillins (34%) and fluoroquinolones (28%), while most residue violations in cattle were due to the presence of penicillins (32%) and aminoglycosides (27%). The overall rates of violations were 0.21% in 2012 and 0.10% in 2013. A major cause of violations was the failure to follow the appropriate withdrawal periods (68.8%). The results of the KNRP were analyzed to provide information on agricultural chemical residues that are of public health concern and to help control and prevent residue violations for ensuring food safety.