LC-MS in food safety analysis

In this chapter, the role of LC-MS in various aspects of food safety analysis is discnssed. LC-MS is important in the quantification and confirmation of identity of food contaminants, e.g., residues of pesticides and related substances in frait and vegetables (Ch. 7.7), antibiotic and antibacterial compounds, other veterinary dmgs, anabolic steroids, and various toxins in feed and food. In addition, attention is paid to the analysis of heterocychc aromatic amines in food. 

An important issue in food safety analysis is the criteria for the confirmation of identity. In a study on the analysis of betalactam antibiotics, Heller and Ngoh [1] apply fonr criteria for spectral comparison  

These eriteria veiy mueh meet the ones reeently established in the EU guidelines [2], These eriteria ate based on the principle of identification points . One point is earned for each ion in the mass spectrum and/or for the precursor ion in a production MS-MS spectrum, and one-and-a-half point for a product ion in the MS-MS spectrum. For the confirmation of Group A (illegal) compounds four identification points are required, while for the confirmation of Group B (legal, but with maximum residue level, MRL) compounds three identification points are required. In addition, ion ratios must be within 20-30% of the ratios in the reference spectrum. 

The fragmentation pathway of sulfonamides has recently been investigated in more detail [9], In negative-ion mode, the fragmentation is similar, except a loss of SO2 rather than HjSOj is observed [10], 

There are some pairs of isomeric sulfonamides, which cannot be unambiguously identified from these fragments. Discrimination between these isomers can be achieved either by two stages of MS-MS in an ion-trap instmment or by means of a combination of in-source collision-induced dissociation (CID) to generate the compound-specific RNHj and subsequent MS-MS on this ion in a triple-quadmpole instrument [11]. 

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