Multi-residue veterinary drug analysis of >200 compounds using MRM Spectrum mode by LC-MS/MS
Veterinary drugs are used for therapeutic, metaphylactic, prophylactic and growth promotion purposes. To provide an assurance that food from animals is safe with regards to residues of veterinary medicines, regulatory authorities have established Maximum Residue Limits (MRL’s) for certain drugs in target tissues and animal species and has also identified pharmacologically active compounds that are prohibited and considered a hazard at any level (EU regulation EC 37/2010; Commission Decision 2003/181/EC; 21CFR Part 556 Tolerances for Residues of New Animal Drugs in Food). In this work, we describe a method that delivers highly sensitive and selective triple quadrupole detection together with MRM Spectrum mode to reduce false positive and false negative reporting. MRM Spectrum mode acquires a high number of fragment ion transitions for each target compound generating a fragmentation spectra that could be used in routine library searching and compound verification using reference library match scores. To reduce false negative and false positive reporting a higher number of MRM transitions were used for each veterinary drug target to increase the level of confidence in compound identification and verification. The number of fragment ion transitions monitored for each target pesticide was dependent upon the chemical structure with typically more than 10 fragment ions for each compound. MRM Spectrum mode combines conventional MRM quantitation with the generation of a high quality MRM product ion spectrum which can be used in routine library searching and compound verification and identification. MRM Spectrum mode was used to quantify and identify 212 drugs (the method included 2,009 MRM transitions) without compromising limits of detection, linearity or repeatability compared to a conventional 2MRM method.