Pesticides in Imported Produce

The CBS workflow focuses on the compounds rather than the individual MRMs. The MRM transition for an analyte does not need to be known. Instead the software auto-fills this information from a compound library containing more than 2,500 MRM transitions covering more than 900 contaminants. Each compound library is then linked to retention time, primary and secondary MRM transitions and collision energy. Using this library, CBS dramatically reduces the time taken to set the initial MRM methods to give accurate data while simultaneously improving workflow productivity.

The below case study explores how LC-MS/MS and GC-MS/MS systems incorporate these hardware and software developments to provide robust, fast, and simple analysis of complex food matrices.

Rapid Pesticide Analysis using LC-MS/MS and GC-MS/MS

Three vegetable matrix samples of rice, avocado, and spinach, representing low moisture content, fatty content, and high moisture content vegetable groups respectively, were extracted using the modified QuEChERS protocol developed at the U.S. FDA Lab at Irvine, shown in Figure 1.

Thirty pesticides amenable for both GC-MS and LC-MS were spiked into three extracted vegetable matrices. Calibration solutions were diluted using extracted blank matrices and prepared for analysis using the EVOQ LC-MS/MS and the SCION GC-MS/MS (Bruker). The MRM method development workflow was set up using Compound Based Scanning. The target pesticides (Table 1) were selected from the software’s MRM library before being exported to the CBS method editor. The dwell time for each MRM is then automatically calculated based on its retention time window (timed MRM). A “built-in” processing method allows for easy updates of the retention times and method parameters and automatically updates qualitative and quantitative ion ratios based on the standards.

Excellent sensitivity was achieved for multi-residue pesticides in various vegetable matrices using both GC-MS/MS and LC-MS/MS systems. Examples of 1 and 5 parts per billion spiked samples in a spinach QuEChERS matrix analyzed by LC-MS/MS and GC-MS/MS are shown in Figures 2a and 2b. R-squared values show excellent linearity was achieved with each matrix.

In Conclusion

The monitoring of pesticides in fruits and vegetables is a key priority for international food safety. Many emerging export economies have substantially different regulations to their Western counterparts. This means stringent monitoring of pesticides is therefore essential to meet international regulatory requirements and ensure product safety. However in complex biological matrices, achieving the accuracy and robustness needed for these routine quality control methodologies can be complex and time consuming. Hardware and software developments in tandem mass spectrometry coupled chromatographic systems provide the sensitivity and selectivity needed for such routine operations, while reducing operator input and instrument down time, and simplifying method development.

Anacleto is VP Applied Markets at Bruker Daltonics. Reach him at [email protected].

References Furnished Upon Request