Post-run target screening strategy for ultra high performance liquid chromatography coupled to Orbitrap based veterinary drug residue analysis in animal urine

The performance of liquid chromatography coupled to high resolution mass spectrometry (LC–HRMS) post-run target screening for veterinary drug residue analysis (sulfonamides, tetracyclines and quinolones) in animal urine has been critically evaluated. It was found that retention time information still remains an essential information and that accurate masses together with relative isotopic abundance data alone are not sufficient for many residue applications. Post-run target screening requires the careful setting of parameters to achieve near zero false negative (above a defined threshold level) and a manageable numbers of false positive findings. HRMS offers many possibilities for the reduction of false positives (e.g. isotopic ratio, isotopic fine structure, exact mass of fragment ions). However, the successful use of such tools requires a sufficient ion intensity. This is often not available when trace level compounds are to be detected. Nevertheless, the proposed method is sufficiently sensitive to detect the veterinary drugs at the relevant concentration levels in urine. This means that the approach is well suited to significantly reduce the number of corresponding meat samples which have to be analyzed in a final step for the regulatory relevant quantification of residue levels in meat. The semi-quantitative screening of many samples for a large number of analytes within a short period of time requires the availability of software tools which provide fast and reliable answers.

► The capabilities of post-target screening with UHPLC–HRMS are critically discussed.
► UHPLC was found to be a mature technology capable in handling “quick and dirty” samples.
► HRMS still requires analyte retention time information, otherwise too many false positive findings are obtained.