Application of HPLC–TOF-MS and HPLC–QTOF-MS/MS for Pesticide Residues Analysis in Fruit and Vegetable Matrices

Abstract Most pesticide residues laboratories perform target analysis on defined pesticide lists, where quantification is a goal, and so good sensitivity and selectivity can be achieved by LC–QqQ-MS/MS; however, international trade and pesticides abuse create the need to identify compounds out of “frequent” target lists. These new market demands make it important to introduce novel equipment capable of performing screening analysis that allows the identification of nontarget compounds, in order to be able to ensure food safety and control the quality of the products that reach the consumer. The use of high resolution and mass accuracy LC–MS systems as provided by TOF-MS is a very valuable solution to cover these demands in a cost-effective way. In the past, the application of TOF instruments to the field of food analysis, and particularly to pesticide analysis, has not been frequent, a consequence of some limitations in performance, but nowadays, its use is extending increasingly due to the improvements achieved in the new equipment. Their characteristic features such as high resolving power, accurate mass measurement, and high full-scan sensitivity make HPLC–(Q)TOF-MS an attractive tool for identifying and quantifying both target and nontarget compounds in vegetable matrices. HPLC–(Q)TOF-MS has the ability to record an unlimited number of compounds operating in full-scan mode, which makes this technique very convenient for the development of screening strategies based on the use of accurate mass databases with automated library-based detection. Another application of HPLC–TOF-MS and HPLC–QTOF-MS/MS for pesticide residues analysis in fruits and vegetables is the identification of pesticide transformation products and metabolites, making use of the great advantage of having the possibility to identify and confirm with one single system. Additionally, as full-scan data are recorded, a posterior analysis is also feasible. However, there are some pitfalls related to false positives and negatives, and careful operation parameters have to be selected. Various strategies or method development based on accurate mass databases, searching software, combined use of TOF-MS and TOF-MS/MS, etc, are commented upon and discussed here. All these aspects are critically discussed in this chapter presenting practical examples of pesticide residue analysis by (Q)LC–TOF-MS in fruits and vegetables.