Date of Award

2011

Document Type

Doctoral Thesis

Degree Name

Doctor of Philosophy

Department

Chemistry

First Advisor

Dr. Ambrose Furey

Second Advisor

Dr. Martin Danaher

Abstract

Ultra high pressure liquid chromatography coupled to triple quadrupole mass spectrometry (UHPLC-MS/MS) technology was utilized for the development of analytical methods for the detection of veterinary drug residues in foods of animal origin. Initial work focused on the development of the mass spectrometry (MS) method for the detection of the analytes of interest and subsequent chromatographic separation. The MS method was optimised to detect both positively and negatively ionised analytes from different classes in a single injection in a 13 minute run time at μg kg-1levels.

Sample preparation procedures were modified to extract the residues from muscle and milk matrices and the quantitative and qualitative methods were validated according to 2002/657/EC. Milk was validated at banned and MRL levels, the CCα of the method was in the range of 0.14-1.9 and 11-123 μg kg-1 respectively. The method was applied to monitoring and surveillance samples through the Irish National monitoring plan. The method was also applied to incurred milk produced from animal studies. Three animal studies were carried out to investigate the presence of nitroxynil in milk, levamisole and oxyclozanide in milk and cheese, and ivermectin and clorsulon in milk and cheese. In general, it was found that residues concentrated more in cheese compared with milk. The data generated by these studies would be useful for decision makers if action limits are to be set, and for animal health companies to set suitable withdrawal periods.

The method for the detection of anthelmintic drugs in muscle was applied to a Europe wide retail survey (n >1000 samples). 2.45% of samples tested were found to contain residues above the reporting limit of the method, only one of these samples was non- compliant for ivermectin as there is no MRL in muscle, however, a newly proposed action limit of 20 μg kg-1 indicates the sample is compliant. The overall results signify that European beef is safe for consumption.

Finally, a specific method for the determination of triclabendazole and its metabolites was developed for liver, muscle and milk around the MRL. This method resulted in an increase in the linearity from 1 to 10 μg kg-1 for the sulphone metabolite to 1-200 and 5-1000 μg kg-1 for milk and tissue respectively. This method was successfully validated according to 2002/657/EC.

Access Level

info:eu-repo/semantics/openAccess

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