Multiresidue determination of veterinary drugs in aquaculture fish samples by ultra high performance liquid chromatography coupled to tandem mass spectrometry.

A simple, selective and fast multiresidue method was developed for the determination of 32 veterinary drug residues belonging to several families, in gilthead sea bream (Sparus aurata) by ultra high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). The extraction was based on modified QuEChERS (quick, easy, cheap, effective, rugged and safe) procedure, using as extraction solution a mixture of acetonitrile and methanol (75:25, v/v), and it reduces sample handling, increasing sample throughput in relation to current methodologies. The developed method was validated and mean recovery ranged from 69% to 125% (at 10, 25, 50 and 100 µg/kg). Intra and interday precision, estimated as the same levels and expressed as relative standard deviation, RSD, were lower than 20% and 30%, respectively. Limits of detection (LODs) and quantification (LOQs) were lower than 7.5 and 25 µg/kg, respectively, except for danofloxacin, oxytetracycline and tetracycline (LOD and LOQ of 15.0 and 50 µg/kg, respectively). Decision limit (CC(α)) and detection capability (CC(ß)) were also calculated and ranged from 16.7 µg/kg (levamisole) to 605.0 (flumequine) µg/kg and from 23.5 µg/kg (levamisole) to 611.5 µg/kg (flumequine), respectively. The expanded uncertainty, U, was also evaluated ant it was below 25% at 100 µg/kg level, except for tetracycline (28%). Finally, the method was applied to ten samples obtained from local supermarkets in Almería (Spain) and traces of some compounds were detected.

Development and validation of a multiclass method for the determination of veterinary drug residues in chicken by ultra high performance liquid chromatography-tandem mass spectrometry.

A multiclass method has been optimized and validated for the simultaneous determination of 20 veterinary drug residues belonging to several classes, as quinolones, sulfonamides, macrolides, anthelmintics, avermectins and diamino derivatives, and benzathine, used as a marker of the presence of penicillin, in muscle chicken. It has been based on QuEChERS methodology (quick, easy, cheap, effective, rugged and safe) and ultra high performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UHPLC-MS/MS). Several chromatographic conditions were optimized, obtaining a running time <8.5 min. The developed method was validated on the basis of international guidelines. Mean recoveries ranged from 70 to 120%, except for benzathine (65.6% at 20 µg kg(-1)) and sulfadimidine (69.0% at 100 µg kg(-1)). Repeatability was lower than 20.0% except for sulfachlorpyridazine (22.1% at 20 µg kg(-1)) and tylosin (20.5% and 20.6% at 30 and 50 µg kg(-1), respectively), whereas reproducibility was lower than 25% except for flumequine (27.4% at 20 µg kg(-1)) and benzathine (37.8% and 27% at 20 and 50 µg kg(-1), respectively). Limits of detection (LODs) and quantification (LOQs) ranged from 3.0 to 6.0 µg kg(-1) and 10.0 to 20.0 µg kg(-1), respectively, except for tylosin that showed a LOD and LOQ of 9.0 and 30.0 µg kg(-1). Decision limit (CC(α)) and detection capability (CC(ß)) were calculated and CC(ß) ranged from 24.1 µg kg(-1) (mebendazole) to 423.6 µg kg(-1) (flumequine). Finally, the method was applied to real samples and traces of some compounds were found in eight samples of chicken and benzathine was detected in one sample at 29.9 µg kg(-1).