title: Extraction and isolation of avermectins and milbemycins from liver samples using unmodified supercritical CO2 with in-line trapping on basic alumina.
abstract: A multi-residue supercritical fluid extraction (SFE) method has been developed for the extraction and isolation of eprinomectin, moxidectin, abamectin, doramectin and ivermectin residues from animal liver. Liver samples are mixed with hydromatrix and packed into a vessel containing 2 g of basic alumina. The samples are extracted at 100 degrees C using unmodified supercritical carbon dioxide (SF-CO2) at a pressure of 300 bar and flow-rate of 5.0 l/min. The analytes are adsorbed in-line on the basic alumina trap, which is later eluted with 4 ml of methanol-ethyl acetate (70:30, v/v). After evaporating to dryness, sample extracts are derivatised using methylimidazole, trifluoroacetic anhydride and acetic acid at 65 degrees C for 30 min. Derivatised sample extracts are analysed by high-performance liquid chromatography (HPLC) with fluorescence detection. The method was validated using bovine liver fortified at levels of 4 and 20 microg/kg with the drugs. The mean recovery ranged between 76 and 97%. The intra- and inter-assay variations showed RSD values <10 and <16%, respectively. The procedure was also applied to ovine and porcine liver, giving similar results. The limit of quantitation of the method is 2 microg/kg.
authors.affiliation: Teagasc, The National Food Centre, Dunsinea, Dublin, Ireland.
authors.forename: M
authors.initials: M
authors.lastname: Danaher
authors.forename: M
authors.initials: M
authors.lastname: O'Keeffe
authors.forename: J D
authors.initials: JD
authors.lastname: Glennon
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000032:analysis*; D002245:Carbon Dioxide; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D025924:Chromatography, Supercritical Fluid / Q000379:methods*; D007559:Ivermectin / Q000031:analogs & derivatives / Q000032:analysis*; D008099:Liver / Q000737:chemistry*; D018942:Macrolides; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012756:Sheep; D013050:Spectrometry, Fluorescence; D013552:Swine
chemical_list: D000900:Anti-Bacterial Agents; D018942:Macrolides; D002245:Carbon Dioxide; D007559:Ivermectin; C019264:avermectin; D000537:Aluminum Oxide; C027837:moxidectin