Occurrence of ivermectin in bovine milk from the Brazilian retail market.
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 C18, with methanol : water (96 : 4 v/v) mobile phase at a flow rate 0.7 ml min-1. The excitation and emission wavelengths of the fluorescence detector were adjusted at 360 and 470 nm, respectively. The linearity of the method was in the range 10-100 ng ivermectin ml-1. Based on a sample of 5.0 ml, the limit of detection and the limit of quantification for ivermectin in milk were 0.6 and 2 ng ml-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 (10 ng ml-1) established by the Brazilian Ministry of Agriculture.
Lobato
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Department of Food Science, Federal University of Lavras (UFLA), PO Box 37, 37200-000 Lavras, MG, Brazil.
Rath
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Reyes
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D000818:Animals; D000977:Antiparasitic Agents / Q000032:analysis*; D001938:Brazil; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004350:Drug Residues / Q000032:analysis*; D005504:Food Analysis / Q000379:methods; D005506:Food Contamination / Q000032:analysis*; D007559:Ivermectin / Q000032:analysis*; D008892:Milk / Q000737:chemistry*
D000977:Antiparasitic Agents; D007559:Ivermectin