A SPREAD STUDY ON THE PRESENCE, IN DIFFERENT ANIMAL MATRICES, OF RESIDUES OF DIFFERENT ORIGIN: PSEUDO-ENDOGENOUS SUBSTANCES AND ENVIRONMENTAL CONTAMINANTS

The presence of xenobiotic residues in food of animal origin represents an issue for both producers and consumers. Many are the classes of substances, which could be present as residues; the most important are veterinary drugs, substances having anabolic effects, or those not authorized, and environmental contaminants. Several European and National legislations are available with the aim of proposing monitoring plans and maximum residue levels. Over the years, new substances become the subject of Control Authorities, which require the development of state-of-the-art methods for the detection of these compounds and, where necessary, the evaluations of their occurrence and the related risk for the consumer’s health. Based on these considerations, this PhD thesis is focused on the development and validation of new analytical methods for the analyses of these compounds in different matrices of animal origin, considering that innovative and sophisticated techniques are always required in order to investigate their presence. The first part of the project is focused on two “pseudo-endogenous”: prednisolone investigated in urine and adrenal gland of pigs and thiouracil in urine and thyroid gland of cows. Concerning prednisolone, it was detected in urine both at the farm and at the slaughterhouse, with a concentration and frequency higher at slaughter, while in the adrenal glands it was detected in 89% of the samples. Regarding thiouracil, and for other thyreostatic drugs, two simple methods without the derivatisation step were developed for their analyses in both cow urine and in thyroid glands. The validated methods showed satisfactory results for the recovery (96–104 % for both the matrices), precision (coefficients of variation were less than 20 % for urine and 21 % for thyroid glands). The decision limit and detection capability for all the compounds were lower than the recommended values. In urine, the decision limit ranged from 6.9 to 7.3 μg L−1, and the detection capability from 8.5 to 9.7 μg L−1, while in thyroid glands these values varied from 6.6 μg kg−1 to 7.4 μg kg−1 and from 8.0 μg kg−1 to 9.7 μg kg−1, respectively. The second part of the project takes in consideration the presence of environmental contaminants in food of animal origin (in particular fish and honey). The first study was focused on the evaluation of the distribution of persistent organic pollutants (POPs) in tuna samples (Thunnus thynnus) from different FAO areas. The results obtained showed that POPs contamination of tuna reflects FAO area contamination, in particular for FAO area 37, Mediterranean and Black seas, which is an enclosed bacin, with heavily populated shores. The second study assessed the occurrence of different classes of contaminants in 59 organic honeys. Residues of many contaminants were found in most of the samples investigated. The majority of honey samples contained at least one of the contaminants, even if their concentrations were found to be lower than its maximum residue level (MRL). Diazinon, Mevinphos, Coumaphos, Chlorpyrifos and Quinoxyfen were the pesticide residues frequently detected in samples. The third study evaluated the effectiveness of accelerated solvent extraction (ASE) compared to QuEChERS methods for the analysis of pesticides in organic honey by gas chromatography-triple quadrupole mass spectrometry. Two simple and rapid ASE methods with “in-line” clean-up, with two different extraction solvents and fat retainers, were optimized and then compared to QuEChERS. The three methods were validated and showed that QuEChERS and ASE with PSA as retainer had better repeatability than ASE with Hexane:EtylAcetate and Florisil. In particular, QuEChERS and ASE (ACN and PSA) showed good recovery, according to the SANTE criteria, for the majority of investigated pesticides. Conversely, when ASE with Hexane:EtylAcetate and Florisil was used as the retainer, several compounds showed recoveries lower than the acceptable value of 70% The last study considered the presence of environmental contaminants in mussels and clams. As done in the previous studies, the analytical methods were validated, showing recovery in the range 70-100 %, coefficients of variation between 2-20 %, and good linearity. The contaminants were detected in most of the samples with the highest prevalence (58 %) in mussels for polychlorinated biphenyls (PCBs), which were also the contaminants with the highest concentration (Σ PCBs = 49.02 ng g-1).