Teresa Szprengier-Juszkiewicz, Piotr Jedziniak, Małgorzata Olejnik and Jan Żmudzki
A sensitive and reliable method has been developed and validated to determine residues of abamectin, doramectin, eprinomectin, ivermectin, and moxidectin in bovine milk. Isolation of the analytes from milk was performed with the use of liquidliquid extraction with acetonitrile in the presence of sodium chloride. The extract was defatted with hexane and cleaned up using solid phase extraction (C8 cartridge) after forming ion pairs with triethylamine. The analytes were derivatized with N, Ndimethylformamide, acetic acid anhydride, and N-methylimidazole (100°C, 90 min). The derivatives were determined by reverse phase liquid chromatography with fluorescence detection (excitation and emission wavelength 365 nm and 475 nm, respectively). Recoveries of the lactones from milk samples fortified at 10-30 μg kg-1 ranged from 52% to 80% with intra-laboratory reproducibility (CV) of 12.7%-22.8%. The critical concentrations (decision limit, CCα and detection capability, CCβ) were in accordance with target limits. The method has been verified in the proficiency studies by EURL/CVL Berlin (all z-scores in the range of ±2). The method was transferred to routine laboratories, verified in inter-laboratory comparison and successfully applied in the National Residue Control Plan.
Piotr Jedziniak, Małgorzata Olejnik, Jolanta G. Rola and Teresa Szprengier-Juszkiewicz
A multiresidue method (LC-MS/MS) for determination of wide range of anthelmintics was developed. The method covered benzimidazoles: albendazole (and metabolites), cambendazole, fenbendazol (and metabolites), flubendazole (and metabolites), mebendazole (and metabolites), oxibendazole, thiabendazole (and metabolites), triclabendazole (and metabolites); macrocyclic lactones: abamectin, doramectin, emamectin, eprinomectin, ivermectin, moxidectin; salicylanilides: closantel, ioxynil, nitroxynil, oxyclosamide, niclosamide, rafoxanid and others: clorsulon, derquantel, imidocarb, monepantel (and metabolites), morantel, praziquantel, and pyrantel. The method was used to examine the potential presence of anthelmintics in goat and sheep milk and dairy products from the Polish market. A total of 120 samples of milk, yoghurt, cottage cheese, cream cheese, and curd were analysed. None of the samples were found positive above CCα (1-10 μg/kg) except for one cottage cheese in which traces of albendazole sulfone were detected (5.2 ug/kg) and confirmed. The results of the study showed negligible anthelmintic residues in the goat and sheep milk and dairy products and confirm their good quality.