Analysis of nitrofuran drug residues in animal tissues using liquid chromatography coupled to tandem mass spectrometry

In this research, an analytical method for the determination of eight bound nitrofuran residues in meat was developed and validated using ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). The method has addressed the traditionally narrow scope of nitrofuran analysis by including new marker chemistries. Full chromatographic separation was achieved for the metabolites of all eight nitrofurans, using phenyl-hexyl column chemistry and a systematic optimisation of the mobile phase additives and gradient profile. The conventional, lengthy sample preparation was substantially shortened by replacing the overnight waterbath derivatisation with a rapid 2 h microwave-assisted reaction, followed by a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) extraction, which is a simplified approach that uses less solvent per sample. The new marker residues of two nitrofuran drugs were confirmed in vivo for the first time in literature. Aminoguanidine was detected in porcine and avian tissues following treatment with nitrovin, and liver was identified as the most suitable target matrix for its analysis. Oxamic acid hydrazide was confirmed as a suitable marker for monitoring nifuraldezone abuse in poultry, and both muscle and liver tissues were found to be appropriate matrices for detection of the residues. Overall, the research presented in this thesis can play a major role in the surveillance of the illegal use of nitrofuran drugs in food-producing animals.