High-performance liquid chromatography (HPLC) with fluorescence detection was used for the quantification of ivermectin residues in bovine milk intended for human consumption. After liquid–liquid extraction of ivermectin and purification of the extract, the compound was derivatized with 1-methylimidazol in N,N-dimethyl formamide to form a fluorescent derivative, which was separated by HPLC, using reversed-phase C 18 , with methanol:water (96:4 v/v) mobile phase at a flow rate 0.7mlmin −1 . The excitation and emission wavelengths of the fluorescence detector were adjusted at 360 and 470nm, respectively. The linearity of the method was in the range 10–100ng ivermectin ml −1 . Based on a sample of 5.0ml, the limit of detection and the limit of quantification for ivermectin in milk were 0.6 and 2ngml −1 , respectively. The recovery rate varied from 76.4 to 87.2%, with an average of 77.9±3.2%, at four fortification levels. The inter-day precision of the method was 13% ( n =5). Of 168 samples analysed, 17.8% contained ivermectin above the limit of quantification. Nevertheless, none of the samples contained ivermectin above the maximum residue limit (10ngml −1 ) established by the Brazilian Ministry of Agriculture.
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residues of veterinary drugs
Document Type: Research Article
Department of Food Science, Federal University of Lavras (UFLA), PO Box 37, 37200-000 Lavras, MG, Brazil
Department of Analytical Chemistry, Institute of Chemistry, State University of Campinas, PO Box 6154, 13084-971 Campinas, SP, Brazil
Department of Food Science, Faculty of Food Engineering, State University of Campinas, PO Box 6121, 13084-971 Campinas, SP, Brazil
July 1, 2006
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