Capillary zone electrophoresis determination of oxytetracycline in pig tissue samples at maximum residue limits

The determination of the antibiotic oxytetracycline (OTC), in pig tissues was investigated by capillary zone electrophoresis (CZE) with a prior solid-phase extraction (SPE) using alkyl-bonded silica and polymeric cartridges. The methodology developed allows determination of OTC in pig kidney, liver and muscle samples with defection limits below maximum residue limit values, and the procedures to extract OTC and clean-up the matrix are simple and reliable. The limit of detection for OTC was 160,120 and 85 mug kg(-1) for kidney, liver and muscle samples, respectively. The average recoveries from spiked samples (200 mug kg(-1) and 1600 mug kg(-1)) were in excess of 63% with coefficients of variation between 2.0 and 9.8%. This method would be useful for routine monitoring of oxytetracycline residues in pig tissues.