Automated offline µ-SPE cleanup in GC-based multi-residue analysis: overcoming the challenges of fatty acids containing matrices

Abstract

The aim of this work was to investigate and optimize the use of offline automated µ-SPE cleanup for the analysis of GC-amenable pesticides in fatty acids containing matrices, such as wheat and linseeds. The manual d-SPE and the automated µ-SPE procedure were compared in terms of analytical performance. Furthermore, different cartridge compositions, loading volumes and elution rates were tested and compared in order to find the best conditions for the cleanup of highly complex QuEChERS raw extracts. In µ-SPE, the key aspect was the PSA capacity for removal of fatty acids, and prevent overloading. The novelty of this research lies in the use of customized µ-SPE cartridges containing higher amounts of PSA, which proved to be the most effective strategy for minimizing matrix effects and enhancing method robustness.. Extracts obtained were cleaner compared to d-SPE, and the addition of analyte protectants (shikimic acid) was required to prevent adsorption of certain analytes in the GC system. The final µ-SPE workflow provided an efficient and reliable cleanup step the highly complex extracts rich in fatty acids tested and improved GC robustness reducing the need for GC-MS maintenance.