Validação intralaboratorial de método quantitativo para determinação múltipla de resíduos de avermectinas em leite bovino por cromatografia líquida de alta eficiência com detecção de fluorescência

Ivermectin and albendazole withdrawal period in goat milk

SUMMARY Theaimthis study was to determine the excretion profile of albendazole and ivermectin residues in milk from goats submitted to antiparasitic treatment. Twenty-four Brazilianmongrel lactating and pluriparous goats, maintained extensively on native pasture were orally treatedwith albendazole or ivermectin. Milk samples were collected before and after vermifuges application, in the days 0, 2, 3 e 4 to albendazole and 0, 3, 7, 14, 21, 28, 35 and 42 to ivermectin. The vermifuges residues were detected by high performance liquid cromatography with ultravioletdetector. The amount of residues contained in themilk was decreasing in function of time. The mean daily rates of decrease of albendazole residues were 63.34%, 40.18 and 100.0%, from the 2ndto the 4thday, respectively; on the 3rdday after treatment, 50% of the samples showed concentrations ≥ 47.61 μg.mL–1, and on the 4thday, no sample had albendazole residue. The amount excreted of ivermectin was similar between the 3rdand 21stday when all samples presented values ≥ 51.90 μg.mL-1; on the 35th day, 50% of the samples showed values above of recommended levels, and on the 42nd day, no sample had detectable ivermectin residue. In conclusion, the milk of Brazilian mongrel goats treated orally with albendazole or ivermectin does not contain its respective residues in detectable amounts from the 4th and 42nddays, respectively, after antiparasitic treatment.

An alternative derivatization reaction to the determination of doramectin in bovine milk using spectrofluorimetry

The doramectin (DOR), which belongs to the avermectins group (AVM), has a high antiparasitic activity and so it has been widely used in food-producing animals. The DOR shows low fluorescence quantum efficiency and as a consequence, chemical derivatization reactions are necessary to produce derivatives with improved luminescent properties before its determination by fluorimetry. As the presence of this compound in food represents a risk to human health, an easy, clean and low cost derivatization reaction, which is alternative to those usually employed and that enables its spectrofluorimetric determination in milk samples, was developed. Ethanolic solutions of DOR, containing sodium hydroxide at a final concentration of 0.25 mol L(-1), after 60 min of heating at 50 °C, produced fluorescent signals 1000 times higher than the original ethanolic solution. Using these optimized conditions, a linear response range that extended from 50.00 to 1000 μg L(-1), with a value of (R(2)) equal to 0.9970, was obtained. Average recovery of DOR was 92.5±1.5% (n=3) in bovine milk fortified samples submitted to a liquid-liquid extraction at low temperature and pre concentration process, indicating the usefulness and effectiveness of the proposed method. The proposed spectrofluorimetric method is an alternative to high-performance liquid chromatography (HPLC) based methods, allowing rapid and simple detection of doramectin in milk samples.