Development and validation of rapid multiresidue and multi-class analysis for antibiotics and anthelmintics in feed by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry

Validation of a LC-MS/MS method for the quantitative analysis of four antibiotics in pig tissues and plasma to assess the risk of transfer of residues to edible matrices after exposure to cross-contaminated feed

Cross-contamination between medicated and non-medicated feed can occur during production, processing, transport or storage of animal feed. This may lead to the presence of low concentrations of antibiotics in supposedly drug-free feed for food production animals, which potentially could also harm consumers due to residues. In addition, consumption of sub-therapeutic concentrations of antibiotics may increase the risk of emergence of resistant bacteria. In this study, LC-MS/MS methods were developed to quantify four antibiotics (sulfadimethoxine, oxytetracycline, trimethoprim and amoxicillin) in several pig matrices, i.e. plasma, muscle, liver, kidneys and faeces. All methods were validated using the accuracy profile, except for amoxicillin in faeces, for which extraction could not be optimised for low concentrations. These methods were then applied as part of an animal study during which several pigs received contaminated feed at a concentration corresponding to 2% of therapeutic dose, in order to evaluate the risk of the presence of residues in animal faeces and tissues. The results showed that sulfadimethoxine is well absorbed and accumulates in the muscle, kidneys and liver, where concentrations were higher than the maximum residue limits (MRLs) authorised in EU legislation. Conversely, oxytetracycline was mostly found in faeces as its oral absorption is very low. Trimethoprim concentrations were slightly higher than the tolerated MRL in the kidneys, but they were below this level in the other tissues. Finally, amoxicillin concentrations remained below the lower limit of quantification of the methods in all matrices.

Recent Advances in Sensing Applications of Molecularly Imprinted Photonic Crystals

Photonic crystals (PhCs) with a brightly colored structure are novel materials and are widely used in chemical and biological sensing. Combining PhCs with molecular imprinting technology (MIT), the molecularly imprinted PhC (MIPC) sensors are fabricated, which can specifically recognize the target molecules. Aside from high sensitivity and selectivity, the MIPC sensors could recognize the naked eye detection because of its optical properties. In this review, an overview of recent advances in sensing applications of MIPC sensors including the responsive mechanisms, application in environmental monitoring, and the application to human health were illustrated. The MIPC sensors all responded to the analytes specifically and also showed high sensitivity in real samples, which provided a method to realize the rapid, convenient, naked eye, and real-time detection. Furthermore, the current limitations and potential future directions of MIPC sensors were also discussed.

Suitability of High-Resolution Mass Spectrometry for Routine Analysis of Small Molecules in Food, Feed and Water for Safety and Authenticity Purposes: A Review

During the last decade, food, feed and environmental analysis using high-resolution mass spectrometry became increasingly popular. Recent accessibility and technological improvements of this system make it a potential tool for routine laboratory work. However, this kind of instrument is still often considered a research tool. The wide range of potential contaminants and residues that must be monitored, including pesticides, veterinary drugs and natural toxins, is steadily increasing. Thanks to full-scan analysis and the theoretically unlimited number of compounds that can be screened in a single analysis, high-resolution mass spectrometry is particularly well-suited for food, feed and water analysis. This review aims, through a series of relevant selected studies and developed methods dedicated to the different classes of contaminants and residues, to demonstrate that high-resolution mass spectrometry can reach detection levels in compliance with current legislation and is a versatile and appropriate tool for routine testing.

Control of Antimicrobials in Feed Using Liquid Chromatography-Tandem Mass Spectrometry: Assessment of Cross-Contamination Rates at the Farm Level

Antimicrobial cross-contamination of animal feed may occur during feed manufacturing, because shared production lines can be used for the production of medicated and nonmedicated feeds, and also during feed transport, storage at the farm level, and usage. This is a major issue in the current context in which antimicrobial usage must be controlled to maintain their effectiveness. The purpose of this study was to assess the antimicrobial cross-contamination rate of feed at the farm level. Here, we optimized a liquid chromatography-tandem mass spectrometry method for the determination of 11 antimicrobials in feed for pigs, poultry, and rabbits, which were strategically chosen. The method was validated according to European regulations in terms of mass spectrometry identification criteria and quantification criteria (linearity, trueness, precision, limit of quantification, and limit of decision). The results were in compliance with these regulations except for doxycycline, which may be quantified with higher uncertainty. This method was applied to the analysis of 192 nonmedicated pig, poultry, and rabbit feed samples that were collected directly from farms to assess antimicrobials animal exposure. Cross-contamination rates were relatively high with 44% of the samples being contaminated at a concentration above the quantification limit of 0.125 mg/kg and 15% of the samples being contaminated above 1 mg/kg. This result suggests that the current regulations and feed processing recommendations need to be improved, taking into account the risks arising from these contaminations.

Identification and Quantification of Tylosin in Animal Feed by Liquid Chromatography Combined with Electrospray Ionisation Mass Spectrometry

Introduction

The authorisation of tylosin as feed additive was withdrawn for reasons of human health concerning resistance of pathogenic bacteria. An analytical method for the identification and quantification of tylosin in animal feed was developed and validated.

Material and Methods

The samples were extracted using an acidified methanol:water mixture and solid-phase extraction was employed for the isolation of the antibiotic from diluted feed samples. Tylosin was analysed by liquid chromatography with electrospray ionisation mass spectrometric detection. The method's performance was evaluated in adherence to the Commission Decision 2002/657/EC.

Results

The recovery of the analyte from spiked samples was determined to be in the range from 78.9% to 108.3% depending on tylosin concentrations. The CCα and CCβ values for tylosin in feeds were determined at 0.085 mg kg^-1 and 0.091 mg kg^-1, respectively. The method detection limit was found to be 0.035 mg kg^-1 and the quantification limit 0.05 mg kg^-1. The applicability of the developed method was tested by analysing real feed samples.

Conclusion

A reliable LC-MS method was developed to identify and quantify tylosin in animal feed with a good repeatability and a high specificity and sensitivity. Because of these characteristics, the proposed method is applicable and could be deemed necessary within the field of feed control and safety.

Advances in the Analysis of Veterinary Drug Residues in Food Matrices by Capillary Electrophoresis Techniques

In the last years, the European Commission has adopted restrictive directives on food quality and safety in order to protect animal and human health. Veterinary drugs represent an important risk and the need to have sensitive and fast analytical techniques to detect and quantify them has become mandatory. Over the years, the availability of different modes, interfaces, and formats has improved the versatility, sensitivity, and speed of capillary electrophoresis (CE) techniques. Thus, CE represents a powerful tool for the analysis of a large variety of food matrices and food-related molecules with important applications in food quality and safety. This review focuses the attention of CE applications over the last decade on the detection of different classes of drugs (used as additives in animal food or present as contaminants in food products) with a potential risk for animal and human health. In addition, considering that the different sample preparation procedures have strongly contributed to CE sensitivity and versatility, the most advanced sample pre-concentration techniques are discussed here.

Determination of Florfenicol, Thiamfenicol and Chloramfenicol at Trace Levels in Animal Feed by HPLC⁻MS/MS

Administration of florfenicol and thiamfenicol through medicated feed is permitted within the European Union, always following veterinary prescription and respecting the withdrawal periods. However, the presence of low levels of florfenicol, thiamfenicol, and chloramfenicol in non-target feed is prohibited. Since cross-contamination can occur during the production of medicated feed and according to Annex II of the European Regulation 2019/4/EC, the control of residue levels of florfenicol and thiamfenicol in non-target feed should be monitored and avoided. Based on all the above, a sensitive and reliable method using liquid chromatography tandem mass spectrometry was developed for the simultaneous detection of chloramfenicol, florfenicol, and thiamfenicol at trace levels in animal feed. Analytes were extracted from minced feed with ethyl acetate. Then, the ethyl acetate was evaporated, the residue was resuspended in Milli-Q water and the extract filtered. The method was in-house validated at carryover levels, with concentration ranging from 100 to 1000 µg/kg. The validation was conducted following the European Commission Decision 2002/657/EC and all performance characteristics were successfully satisfied. The capability of the method to detect amfenicols at lower levels than any prior perspective regulation literature guarantees its applicability in official control activities. The developed method has been applied to non-compliant feed samples with satisfactory results.

Liquid Chromatography Analysis of Common Nutritional Components, in Feed and Food

Food and feed laboratories share several similarities when facing the implementation of liquid-chromatographic analysis. Using the experience acquired over the years, through application chemistry in food and feed research, selected analytes of relevance for both areas were discussed. This review focused on the common obstacles and peculiarities that each analyte offers (during the sample treatment or the chromatographic separation) throughout the implementation of said methods. A brief description of the techniques which we considered to be more pertinent, commonly used to assay such analytes is provided, including approaches using commonly available detectors (especially in starter labs) as well as mass detection. This manuscript consists of three sections: feed analysis (as the start of the food chain); food destined for human consumption determinations (the end of the food chain); and finally, assays shared by either matrices or laboratories. Analytes discussed consist of both those considered undesirable substances, contaminants, additives, and those related to nutritional quality. Our review is comprised of the examination of polyphenols, capsaicinoids, theobromine and caffeine, cholesterol, mycotoxins, antibiotics, amino acids, triphenylmethane dyes, nitrates/nitrites, ethanol soluble carbohydrates/sugars, organic acids, carotenoids, hydro and liposoluble vitamins. All analytes are currently assayed in our laboratories.

Safety assessment of antibiotic and probiotic feed additives for Gallus gallus domesticus

Antibiotics in feed select for resistant strains and is thus a threat to human health. In this study, the effect of a multi-strain probiotic and antibiotics on the growth and health of broilers was studied. Equal numbers of broilers received on a daily basis either a multi-strain probiotic or a combination of sulphadiazine, colistin and trimethoprim, whereas the control group received standard feed. The villi of immature broilers (19 days old) administered antibiotics had a larger surface area and their lymphocyte and basophil counts were higher compared to broilers from the probiotic and control groups. The cecal microbiomes of mature broilers (29 days old) that received probiotics had higher levels of Enterobacteriaceae, but lower numbers of Clostridiales, Brucellaceae, Synergistaceae, Erysipelotrichaceae and Coriobacteriaceae compared to the antibiotic-treated group. A decline in the bioluminescence of Listeria monocytogenes observed for broilers on probiotics suggested that the probiotic may be used to control bacterial infections. No significant differences in total red blood cell, haemoglobin and haematocrit content, and mean values for corpuscular volume, corpuscular haemoglobin and corpuscular haemoglobin numbers were recorded amongst broilers from the different treatment groups. This study provides valuable information on the health and performance of broilers when administered probiotics and antibiotics as additives.