Report for 2013 on the results from the monitoring of veterinary medicinal product residues and other substances in live animals and animal products

Determination of 105 antibiotic, anti-inflammatory, antiparasitic agents and tranquilizers by LC-MS/MS based on an acidic QuEChERS-like extraction

A procedure for screening 105 veterinary drugs in foods by liquid chromatography tandem mass-spectrometry (LC-MS/MS) is presented. Its scope encompasses raw materials of animal origin (milk, meat, fish, egg and fat) but also related processed ingredients and finished products commonly used and manufactured by food business operators. Due to the complexity of the matrices considered and to efficiently deal with losses during extraction and matrix effects during MS source ionisation, each sample was analysed twice, that is 'unspiked' and 'spiked at the screening target concentration' using a QuEChERS-like extraction. The entire procedure was validated according to the European Community Reference Laboratories Residues Guidelines. False-negative and false-positive rates were below 5% for all veterinary drugs whatever the food matrix. Effectiveness of the procedure was further demonstrated through participation to five proficiency tests and its ruggedness demonstrated in quality control operations by a second laboratory.

Oral Fluid as a Biological Material for Antemortem Detection of Oxytetracycline in Pigs by Liquid Chromatography-Tandem Mass Spectrometry

The presence of antibiotic residues in pig tissues requires a search for new methods for their antemortem detection. To find an alternative for postmortem pig carcass analysis, an oral fluid was tested. To prove the suitability of oral fluid for the detection of antibiotics administered by injection, oxytetracycline was chosen. Research was conducted on two groups of animals: group 1, 100% treated; and group 2, 50% treated and 50% untreated. Oxytetracycline was assayed by a high-performance liquid chromatography-tandem mass spectrometry method. The antibiotic was detectable 2 h post administration in group 1 and group 2 at the concentrations of 10653 ± 1421 μg/kg and 7457 ± 1145 μg/kg, respectively. At withdrawal period (21st day), oxytetracycline concentrations in oral fluid (30.8 ± 9.4 μg/kg in group 1 and 11.6 ± 5.6 μg/kg in group 2) were similar to those determined in muscle (34.5 ± 8.2 μg/kg). The concentrations of oxytetracycline in liver and kidney were 76.8 ± 22 μg/kg and 204 ± 49 μg/kg, respectively. The results of this study indicate that oral fluid analysis can be used for antemortem oxytetracycline detection in pigs, even if the half of animals in one pen are treated.