Methodologies for the analysis of veterinary drugs and growth promoters in the scope of food safety control

Veterinary drugs and growth promoters are a part of many chemical hazards that can be found in the modern food chain, and they pose risks to human health such as antimicrobial resistance. The presence of these drug residues increased with intensive farming practices and is an issue of global concern. Food safety authorities around the world establish control programs by scientifically assessing the risk for each drug and set maximum levels for each drug in various matrices. The testing laboratories and analytical methods to test samples from food and feed chain form the core of such programs and provide evidence for regulatory authorities to take decisions. In the drug residue testing, there is a need for improved methods of testing that can provide high selectivity, high throughput, robustness and affordability. In that sense, one main goal of this thesis was to develop analytical methodologies for various families of veterinary drugs and growth promoters in feed, food and biological samples from food producing animals. First three chapters form the introduction of this thesis. Chapter 1 provides an overview on food safety hazards, food safety authorities, legislations for control of veterinary drugs and growth promoters and the role of analytical laboratories in the control program. Chapter 2 covers sample preparation techniques and the typically used chromatographic (LC) and detection (MS) techniques for drug residue testing. Chapter 3 reviews various applications in literature and focus on trends in developing analytical methodologies for food safety testing which move in the direction of comprehensive analysis of samples owing to very high number of contaminants and increasing number of unknown contaminants. Chapter 4 presents a method developed and validated for analyzing eight sulphonamides in six types of feed based on liquid chromatography (LC) and ultraviolet detection. Chapter 5 presents the results from a systematic study of various hydrophilic interaction chromatography (HILIC) stationary phases for analysis of aminoglycosides and also reports two analytical methods based on HILIC- tandem mass spectrometry (MS/MS) for analysis of ten aminoglycosides in honey and animal kidney samples. This work was carried out in collaboration with laboratory of Agencia Salut Publica de Barcelona (ASPB) and the methods were validated according to Decision 2002/657/EC and implemented for routine analysis of samples in accordance with the requirements of ISO 17025: 2005. The laboratory of ASPB acquired an LC- high resolution mass spectrometry (HRMS) instrument and in order to incorporate the instrument for routine targeted analysis, an exploration of various parameters of the equipment was necessary. In that sense, a systematic study to explore various modes of acquisition has been conducted and a method to analyze nine hormones in urine has been transferred to HRMS and is reported in Chapter 6. Gaining understanding about the functioning of the instrument, an improved method to analyze aminoglycosides based on HRMS was developed and reported in Chapter 5.4. Moreover, the LC- HRMS instrument with quadrupole-orbitrap hybrid analyzer has been incorporated in the laboratory for resolving ambiguous test results. A case study of resolving a false positive result from the analysis of ronidazole in meat was presented in Chapter 7. This case study highlights the pitfalls with low resolution mass spectrometry and existing confirmation criteria for identification with mass spectrometric detection. The HRMS in food safety testing for comprehensive analysis of samples, a non targeted screening workflow using various HRMS data mining and analysis tools have been developed and presented in Chapter 8. At the end of this thesis, conclusions and outlook are presented followed by a list of bibliographic literature.