Young male pigs (25-40 kg bw) were treated experimentally with a single 0.4 mg/kg bw, s.c. dose of ivermectin (Ivomec vet. inj., MSD). The disappearance of the drug from the edible tissues 7-21 days after treatment was studied using a sensitive high-performance liquid chromatographic method. The highest residue levels were found at the injection site (up to 59 and 2.6 mg/kg 7 and 14 days post-injection, respectively). Among the other tissues studied, the residue levels 7 days post-injection showed the following order: liver (less than or equal to 50 micrograms/kg) greater than kidney (less than or equal to 25 micrograms/kg) greater than muscle (less than or equal to 20 micrograms/kg). After 21 days only traces of ivermectin (less than or equal to 2 micrograms/kg) could be detected in the muscle and other edible tissues, including the injection site. Similar residue concentrations were found in slaughterhouse material from sows therapeutically treated with ivermectin for parasite infestation. An ordinary culinary preparation of the minced beef muscle from a bull treated with ivermectin resulted in a 45% (boiling) or 50% (frying) decrease in the drug residue. Based on the known toxic effects of the drug and the results of the present and other residue studies, the suggested withdrawal time for Ivomec in edible tissues of swine and cattle is 21 and 28 days, respectively.
The purpose of this investigation is to develop a rapid and simple method for the assessment of organophosphorus pesticides in bovine muscle by using solid-phase extraction (SPE). After extraction with ethyl acetate (EtOAc) the homogenate is centrifuged and filtered through sodium sulfate. The fat is precipitated in methanol by cooling and the extract is diluted with water and passed through a SPE column (Isolute ENV+). After elution with EtOAc, evaporation, and redissolution, the sample is injected into a gas chromatographic (GC) capillary column DB-1701 and detected by a flame photometric detector. Recoveries from bovine muscle fortified with 12 pesticides between 4 and 65 microg/kg include three levels ranging between 59% and 109% for ten of them. The two most polar pesticides (metamidophos and acephate) are not successful. The relative standard deviations are between 1% and 10% for the ten pesticides. A simplex method is used to optimize the GC conditions.
A method has been developed for the determination of clopidol residues in chicken tissues. After extraction and cleanup, clopidol is esterified in a 2-phase system to clopidol propionate, which is determined by gas chromatography. The 2-phase system includes, in addition to the clopidol dissolved in methanol, aqueous borax solution, hexane, propionic anhydride, and pyridine. Use of these reagents precludes the use of explosive or carcinogenic chemicals in the derivatization step, and the method is therefore suitable for routine laboratory analysis. Levels of 0.5 ppb clopidol in tissue can be determined.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.