Comprehensive screening and quantification of veterinary drugs in milk using UPLC-ToF-MS

Microbial screening methods for detection of antibiotic residues in slaughter animals

Monitoring of food products from animal origin for the presence of antimicrobial residues is preferably done using microbial screening methods because of their high cost-effectiveness. Traditionally applied methods fail to detect the maximum residue limits which were established when EU Council Regulation 2377/90 came into effect. Consequently, during the last decade this has led to the development of improved microbial screening methods. This review provides an overview of the efforts expended to bring antibiotic screening methods into compliance with EU legislation. It can be concluded that the current situation is still far from satisfactory.

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Determination of dissolved domoic acid in seawater with reversed-phase extraction disks and rapid resolution liquid chromatography tandem mass spectrometry with head-column trapping

Domoic acid (DA) is the principal neurotoxin responsible for amnesic shellfish poisoning (ASP) and is produced, among other species, by marine diatoms of the genus Pseudo-nitzschia. In this work, a method for the determination of dissolved DA and its isomers present in seawater has been developed, based on a solid-phase extraction (SPE) disks followed by rapid resolution liquid chromatography coupled with tandem mass spectrometry. SPE provided sample desalting and 20-fold concentration of dissolved DA, while complete resolution between DA and its isomers was achieved in less than 3 min with rapid resolution chromatography thus providing high sample throughput. Additionally, a simple on-column chromatographic procedure allowed head-column trapping of DA providing 15-fold higher sensitivity. The conditions developed in this work have shown appropriate quality parameters in a within-laboratory validation. The detection limit was 0.02 ng mL(-1) for the whole method, while trueness ranged between 92.1% and 110.6% recovery and precision between 8.4% and 19.0% relative standard deviation. Expanded uncertainty measured was 1.92, 0.23 and 0.03 for 10.0, 1.0 and 0.1 ng mL(-1) DA concentrations, respectively, which demonstrated the accuracy of this method for confirmation and quantification of DA present at very low concentration levels in seawater.

Simultaneous determination of (fluoro)quinolones antibacterials residues in bovine milk using ultra performance liquid chromatography-tandem mass spectrometry

The ultra performance liquid chromatography-tandem mass spectrometry (UPLC) method had been developed for 22 (fluoro)quinolone(QNs) antibacterials in milk with multiple reaction monitoring (MRM) as acquisition mode. The analytes were extracted from the sample using Mcllvaine buffer by ultrasonic bath, and purified by solid-phase extraction (SPE) cartridge. The residue were dried under nitrogen and dissolved in mobile phase before UPLC-MS/MS final analysis. The calibration curve of six concentrations for 22 QNs showed good linearity and the good correlation coefficients (r> or =0.9851) were achieved. The limit range of quantification was 0.008-0.339microg/kg. The recovery range was 63.1-94.6% except flumequine, nalidixic acid and nadifloxacin. The method was precise: the relative standard deviations of the method for milk were not more than 13.12%. The accuracies and sensitivity of the method were good for simultaneous determination of 22 QNs.