Quinolones identity confirmation
The MS-MS system is well suited for analyte identity confirmation. The ability to provide high-quality data, by exact mass measurements can make the ToF a very compelling instrument for use as confirmatory method [14-16] in the context of EU legislation [17]. According to this regulation, confirmatory methods for organic residues in food shall provide information about the chemical structure of the analytes and mass spectrometric detection is considered suitable in this context. The use of MS techniques of low and high resolution can fulfill the criteria to confirm the identity of residues based on the established system of identification points (IPs) that is related to fragment masses [24-30]. For MS techniques of low resolution three or four ions, depending on the analyte, are necessary for confirmation, whereas techniques of high resolution need only two ions. Wish this system, a minimum of three IPs is required for authorized substances and four for banned compounds [17, 23]. Therefore, use of the QToF system could provide the required IPs by the sum of two ions, the protonated molecular ion and a fragment ion produced by in-source collision-induced dissociation (CID). In addition, similar to other MS techniques with high selectivity (i.e. QqQ) [21, 22], the QTof-system can confirm the presence of residual antimicrobials in food matrices and even though the sensitivity is lower than that achieved by QqQ [23], it can be sufficient to detect substances at levels lower than the maximum residue limits (MRL) established by EU legislation [4, 17].