Efficient porphyrin integrated UiO-66 probes for ratiometric fluorescence sensing of antibiotic residues in milk.

Dual-emissive fluorescence probes were designed by integrating porphyrin into the frameworks of UiO-66 for ratiometric fluorescence sensing of amoxicillin (AMX). Porphyrin integrated UiO-66 showed dual emission in the blue and red region. AMX resulted in the quenching of blue fluorescence component, attributable to the charge neutralization and hydrogen bonds induced energy transfer. AMX was detected using (F438/F654) as output signals. Two linear relationships were observed (from 10 to 1000 nM and 1 to 100 µM), with a limit of detection of 27 nM. The porphyrin integrated UiO-66 probe was used to detect AMX in practical samples. This work widens the road for the development of dual/multiple emissive fluorescence sensors for analytical applications, providing materials and theoretical supporting for food, environmental, and human safety.

[Simultaneous determination of 31 banned veterinary drugs during egg-laying period in poultry eggs by ultra performance liquid chromatography-tandem mass spectrometry].

The consumption of poultry eggs has increased in recent years owing to the abundance of production and improvements in living standards. Thus, the safety requirements of poultry eggs have gradually increased. At present, few reports on analytical methods to determine banned veterinary drugs during egg-laying period in poultry eggs have been published. Therefore, establishing high-throughput and efficient screening methods to monitor banned veterinary drugs during egg-laying period is imperative. In this study, an analytical method based on ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) combined with QuEChERS-based techniques was developed for the simultaneous determination of 31 banned veterinary drugs encompassing nine drug classes (macrolides, antipyretic and analgesic drugs, sulfonamides, antibacterial synergists, anticoccidials, antinematodes, quinolones, tetracyclines, amphenicols) in different types of poultry eggs. The main factors affecting the response, recovery, and sensitivity of the method, such as the extraction solvent, purification adsorbent, LC separation conditions, and MS/MS parameters, were optimized during sample pretreatment and instrumental analysis. The 31 veterinary drug residues in 2.00 g eggs were extracted with 2 mL of 0.1 mol/L ethylene diamine tetraacetic acid disodium solution and 8 mL 3% acetic acid acetonitrile solution, and salted out with 2 g of sodium chloride. After centrifugation, 5 mL of the supernatant was cleaned-up using the QuEChERS method with 100 mg of octadecylsilane-bonded silica gel (C18), 50 mg of N-propylethylenediamine (PSA), and 50 mg of NH2-based sorbents. After nitrogen blowing and redissolution, the 31 target analytes were separated on a Waters CORTECS UPLC C18 analytical chromatographic column (150 mm×2.1 mm, 1.8 µm) at a flow rate, column temperature, and injection volume of 0.4 mL/min, 30 ℃, and 5 µL, respectively. Among these analytes, 26 analytes were acquired in dynamic multiple reaction monitoring (MRM) mode under positive electrospray ionization (ESI+) conditions using (A) 5 mmol/L ammonium acetate (pH 4.5) and (B) acetonitrile as mobile phases. The gradient elution program was as follows: 0-2.0 min, 12%B-30%B; 2.0-7.5 min, 30%B-50%B; 7.5-10.0 min, 50%B; 10.0-10.1 min, 50%B-100%B; 10.1-12.0 min, 100%B; 12.0-12.1 min, 100%B-12%B; The five other target analytes were acquired in MRM mode under negative electrospray ionization (ESI-) conditions using (A) H2O and (B) acetonitrile as mobile phases. The gradient elution program was as follows: 0-2.0 min, 12%B-40%B; 2.0-6.0 min, 40%B-80%B; 6.0-6.1 min, 80%B-100%B; 6.1-8.0 min, 100%B; 8.0-8.1 min, 100%B-12%B. Matrix-matched external standard calibration was used for quantification. The results showed that all the compounds had good linear relationships within their respective ranges, with correlation coefficients of >0.99. The limits of detection (LODs) and quantitation (LOQs) were 0.3-3.0 µg/kg and 1.0-10.0 µg/kg, respectively. The average recoveries of the 31 banned veterinary drugs spiked at three levels (LOQ, maximum residue limit (MRL), and 2MRL) in poultry eggs ranged from 61.2% to 105.7%, and the relative standard deviations (RSDs) ranged from 1.8% to 17.6%. The developed method was used to detect and analyze banned veterinary drugs in 30 commercial poultry egg samples, including 20 eggs, 5 duck eggs, and 5 goose eggs. Enrofloxacin was detected in one egg with a content of 12.3 µg/kg. The proposed method is simple, economical, practical, and capable of the simultaneous determination of multiple classes of banned veterinary drugs in poultry eggs.

[Determination of 12 prohibited veterinary drug residues in pig urine by ultra high performance liquid chromatography-tandem mass spectrometry].

A method was established for the simultaneous detection of 12 prohibited veterinary drugs, including ß2-receptor agonists, nitrofuran metabolites, nitroimidazoles, chlorpromazine, and chloramphenicol, in pig urine. The sample was pretreated by enzymolysis, acid hydrolysis/derivatization, and liquid-liquid extraction combined with solid-phase extraction. Detection was performed using ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Ammonium acetate solution (0.2 mol/L, 4.5 mL) and ß-glucuronidase/aryl sulfatase (40 µL) were added to the sample, which was subsequently enzymolized at 37 ℃ for 2 h. Then, 1.5 mL of 1.0 mol/L hydrochloric acid solution and 100 µL of 0.1 mol/L o-nitrobenzaldehyde solution were added to the sample. The mixture was incubated at 37 ℃ for 16 h, and the analytes were extracted with 8 mL of ethyl acetate by liquid-liquid extraction. The lower aqueous phase obtained after extraction was extracted and purified using a mixed cation-exchange solid-phase extraction column. The extracts were combined, the extraction solution was blow-dried with nitrogen, and the residue was redissolved for determination. The samples were analyzed under multiple-reaction monitoring mode with both positive and negative electrospray ionization, and quantified using an isotope internal standard method. The correlation coefficients (r) of the 12 compounds were >0.99. The limits of detection (LODs) and quantification (LOQs) of chloramphenicol were 0.05 and 0.1 µg/L, respectively, and the LODs and LOQs of the other compounds were 0.25 and 0.5 µg/L, respectively. The mean recoveries and RSDs at 1, 2, and 10 times the LOQ were 83.6%-115.3% and 2.20%-12.34%, respectively. The proposed method has the advantages of high sensitivity, good stability, and accurate quantification; thus, it is suitable for the simultaneous determination of the 12 prohibited veterinary drug residues in pig urine.

Solid phase extraction technology combined with UPLC-MS/MS: a method for detecting 20 ß-lactamase antibiotics traces in goat's milk.

We develop and validate a method for the rapid determination and identification of 20 ß-lactamase antibiotics traces in goat's milk by combining the solid phase extraction technology with ultra-high performance liquid chromatography-tandem mass spectrometry. Goat milk samples were extracted with acetonitrile twice. The supernatant was then extracted and cleaned by solid-phase extraction using divinylbenzene and N-vinylpyrrolidone copolymer. The method was validated, with limits of quantification (LOQs) of 0.3 µg kg-1, specificities of 1/3 LOQ, linearities (R2) > 0.99, recoveries of 80-110%, repeatabilities <10.0%, and intermediate precisions <10.0%. The developed method was suitable for the routine analysis of ß-lactamase antibiotics residues in goat's milk and was used to test 76 goat milk samples produced in China.

State-of-the-art nanosensors and kits for the detection of antibiotic residues in milk and dairy products.

Antibiotic resistance is increasingly seen as a future concern, but antibiotics are still commonly used in animals, leading to their accumulation in humans through the food chain and posing health risks. The development of nanomaterials has opened up possibilities for creating new sensing strategies to detect antibiotic residues, resulting in the emergence of innovative nanobiosensors with different benefits like rapidity, simplicity, accuracy, sensitivity, specificity, and precision. Therefore, this comprehensive review provides pertinent and current insights into nanomaterials-based electrochemical/optical sensors for the detection of antibitic residues (ANBr) across milk and dairy products. Here, we first discuss the commonly used ANBs in real products, the significance of ANBr, and also their binding/biological properties. Then, we provide an overview of the role of using different nanomaterials on the development of advanced nanobiosensors like fluorescence-based, colorimetric, surface-enhanced Raman scattering, surface plasmon resonance, and several important electrochemical nanobiosensors relying on different kinds of electrodes. The enhancement of ANB electrochemical behavior for detection is also outlined, along with a concise overview of the utilization of (bio)recognition units. Ultimately, this paper offers a perspective on the future concepts of this research field and commercialized nanomaterial-based sensors to help upgrade the sensing techniques for ANBr in dairy products.

Detection of selected antimicrobial residues in red meat and kidney of beef cattle slaughtered at Nekemte municipal abattoir, Ethiopia.

BACKGROUND: Antibiotics are commonly used drugs in farm animals for therapeutic, prophylactic and diagnosis purposes. As a result of the use of antibiotics in livestock, residues of antibiotics may be present in animal-derived foods, especially in meat. This study aimed at determining the antibiotic residues in cattle slaughtered at Nekemte municipal abattoir and assessing the knowledge, attitude and practice (KAP) level of the community about antibiotic residue in food of cattle origin. MATERIALS AND METHODS: A cross-sectional study was conducted on randomly selected kidney and muscle samples slaughtered at Nekemte municipal abattoir. The samples were collected aseptically and analysed using liquid chromatography mass spectrometer. In addition the KAP of cattle handlers, butcher men and meat users were collected using structured questionnaire. The data was analysed by SPSS and intercooled Stata version 7.0, 2001. RESULTS: Results are presented as percentages and frequency distributions in tabular and graphical form. From 120 individuals interviewed, only 25.83% knew about withdrawal time and had limited knowledge on effect of antibiotic residue on human health, whereas about 47.5% did not heard about antibiotic residue in meat. Tetracycline was detected in all the sampled meat 60 (100%), whereas oxytetracycline residues were detected in half 15 (50%) of the samples. In the current study doxycycline, sulphadiazine, penicillin G and enrofloxacin were not detected in all samples. Oxytetracycline residue levels ranged from 0.00 to 463.35 µg/kg for the kidney and 0.00 to 354.55 µg/kg for muscle samples. About 10% of kidney and 3.33% muscle samples collected had oxytetracycline residues above maximum residue limits. CONCLUSION: In general, the study revealed that oxytetracycline residues were prevalent among antimicrobial residues analysed from the study area. The study indicated the presence of high antimicrobial residue and hence exposes for antimicrobial resistance of pathogens warranting coordinated effort to mitigate its health effect on the animal and hence human being.

The two faces of antibiotics: an overview of the effects of antibiotic residues in foodstuffs.

Antibiotics, which have been used for many years to treat infections, also play an important role in food contamination with antibiotic residues. There is also unnecessary use of antibiotics, particularly to increase production efficiency. Non-compliance with withdrawal periods and maximum residue limits (MRLs) for antibiotics used in food-producing animals results in undesirable events, such as allergic reactions, teratogenicity, carcinogenicity, changes in the microbiota and, in particular, antibiotic resistance. Therefore, it may be useful to avoid unnecessary use of antibiotics, to limit the use of antibiotics and to turn to alternatives that can be used instead of antibiotics. The aim of this review is to provide information on the undesirable effects of antibiotic residues in food-producing organisms and in the environment, their determination, and the precautions that can be taken.

A high-throughput UPLC-MS-MS Bio-analytical method for the analysis of veterinary pharmaceutical residues in Chicken Tissues, Application of efficient-valid-green (EVG) Framework as a Competence Tool.

Antibacterial medications are receiving the most attention due to hypersensitivity reactions and the emergence of bacterial mutants resistant to antibiotics. Treating Animals with uncontrolled amounts of antibiotics will extend beyond their lives and affect humans. This study aims to determine the concentration of the residues of sulfadimidine, sulfaquinoxaline, diaveridine, and vitamin K3 in the tissues of poultry (muscles and liver) after treatment with the combined veterinary formulation. A UPLC-MS-MS method was developed using Poroshell 120 ECC18 and a mobile phase composed of acetonitrile and distilled water, containing 0.1 % formic acid, in the ratio of (85:15 v/v) at a flow rate of 0.6 mL/min. Sample extraction solvent was optimized using response surface methodology (RSM) to be acetonitrile: methanol in the ratio (49.8: 50.2 v/v), and the method was validated according to the FDA bioanalytical method validation protocol over the range (50-1000 µg/Kg) for sulfaquinoxaline and (50-750 µg/Kg) for the other 3 drugs. The greenness of the sample preparation and analytical method was assessed by applying Analytical Eco-scale (AES) and AGREE coupled with AGREEprep. The Competence of the study was evaluated via the EVG framework known as Efficiency, validation, and greenness, to achieve a balance point represented by a radar chart. The method was applied to decide the time required for poultry products to be safe for human use after administration of the studied drugs. It was found that, after the administration of the last dose, minimally 7 days are required till the levels of the drugs drop to the maximum residue limit determined by the FDA/WHO in animal tissues.

Advances in magnetic analytical extraction techniques for detecting antibiotic residues in edible samples.

The widespread use of antibiotics in agricultural and animal husbandry to treat bacterial illnesses has resulted in a rise in antibiotic-resistant bacteria. These bacteria can grow when antibiotic residues are present in food items, especially in edible animal products. As a result, it is crucial to monitor and regulate the amounts of antibiotics in food. Magnetic analytical extractions (MAEs) have emerged as a potential approach for extracting antibiotic residues from food using magnetic nanoparticles (MNPs). Recent improvements in MAEs have resulted in the emergence of novel MNPs with better selectivity and sensitivity for the extraction of antibiotic residues from food samples. Consequently, this review paper addresses current developments in MAE for extracting antibiotic residues from edible samples. It also provides a critical analysis of contemporary MAE practices. The current issues and potential future developments in this field are also discussed, thereby providing a framework for future study paths.

Stability of thirteen antimicrobials in incurred samples of animal tissues, milk, eggs, and honey after freeze-storage.

Monitoring of antimicrobials residues in food of animal origin is performed by control laboratories to ensure public health, and knowledge of the stability of antimicrobials during storage is essential for the reliability of results. For stability studies, analysis of incurred samples is preferential to fortified samples due to the possible conversion of antimicrobial metabolites back to parent compounds during sample preparation, storage, and analysis of the incurred samples, resulting in an increased concentration of the analyte. We have analyzed the concentrations of 13 antimicrobials from 8 groups (tetracyclines, fluoroquinolones, phenicols, sulfonamides, aminoglycosides, penicillins, macrolides, and nitroimidazoles) at different time points of freeze-storage (1 week; 1, 2, and 3 months) using HPLC-MS/MS. Incurred samples were prepared from muscle tissue, liver, kidneys, eggs, and milk taken from different animals (cows, pigs, poultry, goats, and fish). Incurred and fortified samples of honey were investigated as well. The results have shown that all analytes in all samples were stable during the investigated periods regardless of animal species, matrix, and concentration levels.

Extention and interlaboratory comparison of an LC-MS/MS multi-class method for the determination of 15 different classes of veterinary drug residues in milk and poultry feed.

An HPLC-MS/MS multi-class method for quantitation of 15 different classes of veterinary drug residues (>140 analytes) in milk and poultry feed was developed and validated. Accuracy criteria for routine laboratories were met for the majority of analytes, > 83 % in milk and between 50 and 60 % in chicken feed, with an apparent recovery of 60-140 %. Extraction efficiency criteria were met for >95 % of the analytes for milk and > 80 % for chicken feed. Intermediate precision meets the SANTE criterion of RSD < 20 % for 80-90 % of the analytes in both matrices. For all analytes with an existing MRL in milk, the LOQ was below the related MRL. Twenty-nine samples of commercial milk and chicken feed were analyzed within the interlaboratory comparison. No residues of veterinary drugs were found in the milk samples. However, the feed samples exhibited high levels of nicarbazin, salinomycin, and decoquinate.

Comparison of gamithromycin residue depletion in yellow-feather and white-feather broilers after one single subcutaneous injection.

This study aimed to compare the residue depletion of gamithromycin in yellow-feather and white-feather broilers, using Sanhuang and Arbor Acres chickens as typical examples, respectively. Each breed (54 chickens) received a single subcutaneous dose of gamithromycin at 7.5 mg/kg bodyweight (BW). Tissues, including muscle, skin + fat, liver, kidney, and injection site, were collected at 6 h, 3, 5, 7, 10, 14, 21, 28, and 35 d postdrug administration. Gamithromycin concentrations in these tissues were determined using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The kinetics of gamithromycin were analyzed in different tissues using a noncompartmental method in the Phoenix software. Differences were observed in gamithromycin concentrations and kinetic characteristics in both breeds of chickens, with higher residue concentrations and longer residue times found in yellow-feathered broilers. In Sanhuang broilers, the elimination rates of gamithromycin followed this order: injection site > muscle > liver > kidney > skin + fat. The corresponding elimination half-lives (t1/2λzs) in these samples were 1.22, 1.30, 1.71, 2.04, and 2.52 d, respectively. In contrast, in Arbor Acres broilers, a different order was noted: muscle > injection site > kidney > liver > skin + fat, with corresponding t1/2λzs of 1, 1.23, 1.88, 1.93, and 2.21 d, respectively. These differences may be related to variations in pigments in various tissues of chickens of the 2 breeds. However, further investigations are warranted to discern the underlying reasons.

An immunochromatographic strip sensor for marbofloxacin residues.

Marbofloxacin (MBF) was once widely used as a veterinary drug to control diseases in animals. MBF residues in animal food endanger human health. In the present study, an immunochromatographic strip assay (ICSA) utilizing a competitive principle was developed to rapidly detect MBF in beef samples. The 50% inhibitory concentration (IC50) and the limit of detection (LOD) of the ICSAs were 2.5 ng/mL and 0.5 ng/mL, respectively. The cross-reactivity (CR) of the MBF ICSAs to Ofloxacin (OFL), enrofloxacin (ENR), norfloxacin (NOR), and Ciprofloxacin (CIP) were 60.98%, 32.05%, 22.94%, and 23.58%, respectively. The CR for difloxacin (DIF) and sarafloxacin (SAR) was less than 0.1%. The recovery rates of MBF in spiked beef samples ranged from 82.0% to 90.4%. The intra-assay and interassay coefficients of variation (CVs) were below 10%. In addition, when the same authentic beef samples were detected in a side-by-side comparison between the ICSAs and HPLC‒MS, no statistically significant difference was observed. Therefore, the proposed ICSAs can be a useful tool for monitoring MBF residues in beef samples in a qualitative and quantitative manner.

Detection of antibiotic residues in groundwater with a validated multiresidue UHPLC-MS/MS quantification method.

The occurrence of antibiotic residues in the environment has received considerable attention because of their potential to select for bacterial resistance. The overuse of antibiotics in human medicine and animal production results in antibiotic residues entering the aquatic environment, but concentrations are currently not well determined. This study investigates the occurrence of antibiotics in groundwater in areas strongly related to agriculture and the antibiotic treatment of animals. A multiresidue method was validated according to EU Regulation 2021/808, to allow (semi-)quantitative analysis of 78 antibiotics from 10 different classes: ß-lactams, sulfonamides, tetracyclines, lincosamides, amphenicols, (fluoro)quinolones, macrolides, pleuromutilins, ansamycins and diaminopyrimidines using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). This method was used to test different storage conditions of these water samples during a stability study over a period of 2 weeks. Sulfonamides, lincosamides and pleuromutilins were the most stable. Degradation was most pronounced for ß-lactam antibiotics, macrolides and ansamycins. To maintain stability, storage of samples at -18 °C is preferred. With the validated method, antibiotic residues were detected in groundwater, sampled from regions associated with intensive livestock farming in Flanders (Belgium). Out of 50 samples, 14% contained at least one residue. Concentrations were low, ranging from < LOD to 0.03 µg/L. Chloramphenicol, oxolinic acid, tetracycline and sulfonamides (sulfadiazine, sulfadoxine, sulfamethazine and sulfisoxazole) were detected. This study presents a new method for the quantification of antibiotic residues, which was applied to investigate the presence of antibiotic residues in groundwater in Flanders.

Comparison of filter membranes in the analysis of 183 veterinary and other drugs by liquid chromatography-tandem mass spectrometry.

Although filtration is one of the most common steps in sample preparation for chemical analysis, filter membrane materials can leach contaminants and/or retain some analytes in the filtered solutions. In multiclass, multiresidue analysis of veterinary drugs, it is challenging to find one type of filter membrane that does not retain at least some of the analytes before injection in ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). In this study, different filter membranes were tested for use in UHPLC-MS/MS analysis of 183 diverse drugs in bovine muscle, kidney, and liver tissues. Membranes evaluated consisted of polytetrafluoroethylene (PTFE), polyvinylidene difluoride (PVDF), polyethersulfone, nylon, and regenerated cellulose. Drug classes represented among the analytes included ß-agonists, ß-lactams, anthelmintics, macrolides, tetracyclines, sulfonamides, tranquilizers, (fluoro)quinolones, anti-inflammatories, nitroimidazoles, coccidiostats, phenicols, and others. Although the presence of a matrix helped reduce the binding of analytes on surface active sites, all of the filter types partially retained at least some of the drugs in the final extracts. In testing by flow-injection analysis, all of the membrane filters were also observed to leach interfering components. Ultimately, filtration was avoided altogether in the final sample preparation approach known as the quick, easy, cheap, effective, rugged, safe, efficient, and robust (QuEChERSER) mega-method, and ultracentrifugation was chosen as an alternative.

An account of the occurrence of residues from veterinary drugs and contaminants in animal-derived products: a case study on Brazilian supply chains.

Brazil plays an important role in ensuring its position on the international market by assuring high food safety standards for its products, and all products should meet the requirements for residues from veterinary drugs and contaminants in animal products. Statutory monitoring provides insights into the compliance of the Brazilian industry regarding these legal requirements. The objective of this study was to provide insight into the safety of Brazilian animal products by reporting the occurrence of residues from veterinary drugs and contaminants according to an analysis of an 11-year report published by the Brazilian Ministry of Agriculture, Livestock and Food Supply (MAPA). Between 2010 and 2021, 166,647 samples from animal-derived products were analyzed in Brazil, and 624 of those samples were non-compliant (0.37%) exceeding maximum residue limits (>MRLs) or showed the presence of prohibited substances. The most common types of substances found in the non-compliant samples were heavy metals, parasiticides, and antimicrobials, accounting for 82% of all documents from the MAPA. Among Brazilian products, the challenge related to occurrence of substances varied across the food supply chain, with highest incidence rates observed in the fish chain, followed by eggs, milk, equids, sheep/goat, honey, bovine, swine, and broilers chains in decreasing order. Considering the type of substance, heavy metals were found to be more prevalent in fish products, mainly arsenic in wild fish. The prevalence of contaminants and heavy metals decreased, while that of veterinary drugs increased in Brazilian products from 2010 to 2021. From these results, it can be concluded that the number of accidental incidents including those associated with environmental contaminants decreased over the last decade, opposed to those involving human adversaries and deliberate illegal actions, such as the abuse of veterinary drugs, increased. Future monitoring plans need to take this paradigm shift into account.

Determination of marker residues of quinoxaline-1,4-di-N-oxides and its prototype identification by liquid chromatography tandem mass spectrometry.

Quinoxaline-1,4-di-N-oxides (QdNOs), such as carbadox, olaquindox, mequindox, quinocetone, etc. are a class of antibacterial drugs. Prototype drugs residues can not be detected due to their rapid metabolism in animals. Quinoxaline-2-carboxylic acid (QCA) and 3-methyl-QCA (MQCA) are their common marker residues, so it has been always a challenge to trace the specific QdNOs drug used in food animal production. Herein, a liquid chromatography tandem mass spectrometry method was developed to determine QCA and MQCA, and meanwhile, the prototype drugs were identified by analyzing bis-desoxy QdNOs metabolites in single ion-pair monitoring mode. The method indicated that the average recoveries for QCA and MQCA were from 90 % to 105 % with relative standard deviations below 10 %, and the limits of quantification were 1.0 µg/kg. The limits of detection of five bis-desoxy QdNOs (qualitative markers) reached 0.5 µg/kg. This new analytical strategy can effectively solve the identification problem of QdNOs drugs in animal-derived food.

Occurence of antimicrobial residues in milk and labneh consumed in Lebanon.

Antimicrobials are administered in livestock for different uses leading to milk contamination and several undesirable effects. Because there is a lack of surveillance of antimicrobial residues (AMRs) in milk and dairy products in Lebanon, this study aims to determine the occurrence of AMRs in 90 Lebanese samples of milk and labneh (concentrated yoghurt). Multi-residue screening methods with suitable sample preparations were applied to detect 71 AMRs in milk and labneh, respectively, using LC-MS/MS. Of the total number of samples, 71% was contaminated with AMRs and (fluoro)quinolones and macrolides were the most detected families. Additional confirmation tests proved that 6.7% of the milk samples were non-compliant for the macrolides tilmicosin, tulathromycin and spiramycin. Moreover, some labneh prepared from contaminated milk samples was analysed to determine the fate of AMRs during the manufacturing process. The results showed that some AMRs could be concentrated, eliminated or degraded, based on their physicochemical characteristics.

Depletion of dexamethasone in cattle: Food safety study in dairy and beef cattle.

Dexamethasone is approved for cattle in Canada for several conditions, but no withdrawal times are currently provided on the approved labels. Recently, the list of Maximum Residues Limits for Veterinary Drugs in Foods in Canada was amended to include dexamethasone. The objectives of this study were to determine the residue depletion profile of dexamethasone after an extra-label dosage regimen in milk of healthy lactating dairy cattle (n = 18) and in edible tissues of healthy beef cattle (n = 16) and to suggest withdrawal intervals. Dexamethasone was administered intramuscularly at 0.05 mg/kg daily for 3 days. Milk samples were collected prior to treatment and every 12 h up to 96 h post-dose. Muscle, liver, kidney, and peri-renal fat tissues were collected from beef cattle at 3, 7, 11, or 15 days post-dose. Dexamethasone analysis was performed by liquid chromatography/mass spectrophotometry. Dexamethasone residues were detected in milk samples up to 36 h. Muscle and fat had no detectable dexamethasone residues while kidney and liver had detectable residues only on day 3 post-dose. A withdrawal interval of 48 h for milk in Canadian dairy cattle and 7 days for meat in Canadian beef cattle are suggested for the dexamethasone treatment regimen most commonly requested to CgFARAD™.

Determination of Tilmicosin in Bovine, Swine, Chicken, and Turkey Tissues by Liquid Chromatography With Tandem Mass Spectrometry, Single-Laboratory Validation.

BACKGROUND: An LC-MS/MS method was developed for determination and confirmation of tilmicosin in bovine, swine, chicken, and turkey tissues (liver, kidney, muscle, and skin/fat) and bovine milk. OBJECTIVE: The method was subjected to single-laboratory validation to establish method performance parameters. METHOD: Animal tissues and bovine milk were fortified at four concentrations ranging from 0.5 times the lowest maximum residue limit (MRL) or tolerance to 2 times the highest MRL or tolerance considering the Codex and EU MRLs and the US tolerances in the various tissues and milk studied. Incurred tissues were analyzed to verify the precision of the method. RESULTS: The data demonstrated linearity of matrix-matched calibration curves using a weighted (1/×) regression. Recoveries varied from 83.3 to 107.1%. Repeatability precision (RSDr) ranged from 0.465 to 13.4% and intermediate precision (RSDi) ranged from 2.24 to 14.7% in fortified tissue. Repeatability of the method was verified in incurred tissues, ranging from 3.41 to 16.0%. The limits of detection and quantitation of the method are presented and vary by matrix. One confirmatory transition ion was examined across all matrixes and met US and EU criteria for mass spectrometry confirmation. The method was shown to be robust when small changes in method parameters were made, and stability of the analyte in fortified tissues, extracts, standard solutions, and matrix-matched standards was estimated. CONCLUSIONS: The data satisfy the requirements of the AOAC Stakeholder Panel for Veterinary Drug Residue Methods for single-laboratory validation studies and the U.S. Food and Drug Administration Center for Veterinary Medicine Guidance for Industry #208 (VICH GL49). HIGHLIGHTS: The LC-MS/MS method was demonstrated to be suitable for determination and confirmation of tilmicosin residues in bovine, swine, chicken, and turkey tissues and bovine milk based on Codex and EU MRLs and US tolerances.