Automated Clean-up of QuEChERS Extracts for GC-MS and LC-MS

Significance of the Topic

QuEChERS extraction, established in 2003, is a global standard for multi-residue pesticide analysis in food matrices. While extraction is standardized by AOAC and CEN, the clean-up step remains challenging across diverse samples. The automated micro-solid phase extraction (µSPE) approach unifies clean-up for all matrices, improving throughput and performance.

Objectives and Study Overview

This work presents an automated clean-up workflow integrating µSPE cartridges with PAL RTC autosampler operation. The goal is to replace manual dSPE with a mini-column SPE, achieving consistent pesticide recoveries and reduced solvent consumption for GC-MS and LC-MS analysis.

Methodology and Instrumentation

The unified clean-up uses 33×8 mm µSPE cartridges containing 45 mg sorbent. A liquid syringe on the PAL autosampler controls flow at ~2 µL/s for conditioning, sample loading (150 µL raw extract), washing, and elution (100 µL formate buffer in acetonitrile). The syringe acts as an LC pump, eliminating dilution and evaporation steps. Additional steps include addition of internal standard, analyte protectant, and direct injection into GC-MS or LC-MS.

Main Results and Discussion

Linearity coefficients for 208 pesticides exceeded 0.99. The µSPE clean-up showed recoveries between 70–130% with relative standard deviations below 10%, meeting regulatory requirements. The miniaturized format prevented sample dilution and maintained sharp analyte peaks.

Benefits and Practical Applications

• Enhanced clean-up across simple, complex, and high-chlorophyll matrices
• Significant reduction in solvent usage and waste generation
• Elimination of evaporation steps accelerates sample throughput
• Parallel preparation during chromatographic runs improves laboratory efficiency

Future Trends and Opportunities

The µSPE automation paves the way for broader integration with high-resolution MS systems, expanded contaminant panels, and further miniaturization. Ongoing developments may focus on novel sorbent chemistries and fully automated end-to-end sample preparation platforms.

Conclusion

Automated µSPE clean-up delivers a universal, green, and efficient solution for QuEChERS extracts, ensuring robust pesticide residue analysis in GC-MS and LC-MS without manual intervention or concentration steps.

References

1. Morris BD, Schriner RB. Development of an Automated Column Solid-Phase Extraction Cleanup of QuEChERS Extracts, Using a Zirconia-Based Sorbent, for Pesticide Residue Analyses by LC-MS/MS. J Agric Food Chem. 2015;63:5107–5119. DOI:10.1021/jf505539e.
2. Lehotay SJ, Han L, Sapozhnikova Y. Automated Mini-Column Solid-Phase Extraction Cleanup for High-Throughput Analysis of Chemical Contaminants in Foods by Low-Pressure Gas Chromatography-Tandem Mass Spectrometry. Chromatographia. 2016. DOI:10.1007/s10337-016-3116-y.
3. Hayward M, Ho J. Automated Chromatographic Solid-Phase Extraction Using an Autosampler. American Laboratory. 2016.
4. Hübschmann HJ, Böhm G, Bolliger R. Automated micro-SPE Clean-up of QuEChERS Extracts for Multi-Residue Pesticide Analysis. Poster at LAPRW 2017; Poster Number: 2071.