Determination of residual pharmaceuticals in edible animal tissues by continuous solid-phase extraction and gas chromatography-mass spectrometry.

A sensitive, reliable method using continuous solid-phase extraction and gas chromatography-mass spectrometry was developed for the simultaneous determination of twenty pharmaceuticals including antibacterials, anti-epileptics, antiseptics, β-blockers, lipid regulators, hormones and non-steroidal anti-inflammatories at trace levels in edible animal tissues. The procedure involves deproteination and delipidation of samples by precipitation/centrifugation/filtration, followed by sample enrichment and cleanup by continuous solid-phase extraction. The proposed method was validated with quite good analytical results including low limits of detections (0.4-2.7 ng kg(-1) for 2g of sample) and good linearity (r(2)>0.995) throughout the studied concentration ranges. In addition, the method is quite accurate (recoveries ranged from 92 to 101%) and precise (within-day and between-day RSD values were less than 7%), which allows the determination of residual pharmaceuticals in tissues from agricultural farm and fish hatchery animals (pig, veal, lamb and chicken muscle, kidney and liver; and salmon, sea bass and sole flesh). The analytes most frequently found in the studied samples were the hormones estrone and 17β-estradiol, and the antibacterials florfenicol and pyrimethamine.