Occurrence of macrocyclic lactones in milk and yogurt from Brazilian market

Avermectins and milbemycins belong to a family of compounds called macrocyclic lactones (ML) and are highly used as antiparasitic agents in the treatment of cattle for control of gastrointestinal nematodes, ticks and myiasis. In Brazil, there are five substances (ivermectin, abamectin, doramectin, eprinomectin and moxidectin) registered for bovines. The use of these compounds may bring benefits to the cows but indiscriminate use might result in the presence of residues in milk and dairy products. In this context, the objective of the study was to validate an analytical method for determination of five ML in dairy products and verify the occurrence of these compounds in milk and yogurt available in the Brazilian market. The method involved QuEChERS sample preparation, derivatization and determination by high performance liquid chromatography with fluorescence detection. The methodology was validated using organic samples of milk and yogurt for the following parameters: linearity, precision, accuracy, repeatability and limits of detection (LOD) and quantification (LOQ). The method showed good linearity. Average recovery, performed at three different levels varied from 83% to 112% (RSDs < 14%). The method provides LOD ranging from 0.4 to 3.2 μg L^?1 for milk and 0.6 to 0.9 μg kg^?1 for yogurt. The LOQ was established according to the lower spike level (0.2–10 μg L^?1 for milk and 2.5 μg kg^?1 for yogurt). Repeatability and within-laboratory reproducibility were in satisfactory for both matrixes. In order to monitor milks and yogurts marketed in Campinas, SP, Brazil, 13 brands of UHT milk (135 samples), 8 brands of pasteurized milk (103 samples) and 13 brands of yogurt (104 samples) were acquired. A total of 342 samples were analyzed in duplicate for the presence of ivermectin, abamectin, doramectin, eprinomectin and moxidectin. Moxidectin was detected in one sample of pasteurized milk. No residue of the analyzed compounds was found in UHT milk or yogurt. Results indicate that the consumption of milk and yogurt does not represent a health risk for Brazilian consumers.