Analysis of Pesticides in Broccoli Using Universal dSPE with Carbon S and GC/TQ

Significance of the Topic

Broccoli, like many leafy vegetables, contains abundant pigments such as chlorophyll and lutein that can co-extract during pesticide analysis, causing matrix effects and interfering with accurate quantitation on GC/TQ systems. Effective cleanup is essential to protect instrument performance and achieve reliable pesticide recoveries, particularly for planar compounds prone to adsorption losses with traditional graphitized carbon black (GCB).

Objectives and Study Overview

This study aimed to develop and validate a streamlined GC/TQ analytical workflow for multi-residue pesticide analysis in broccoli. It compared cleanup performance of the Agilent Bond Elut QuEChERS dSPE universal kit with Carbon S to a conventional GCB sorbent, focusing on recoveries of planar pesticides and overall matrix removal efficiency.

Methodology

A 10 g homogenized broccoli sample was spiked with mixed pesticide standards (1–200 ppb calibration range; 5 ppb QC level), extracted with acetonitrile using the EN 15662 QuEChERS salt packet, and homogenized by Geno/Grinder at 1 500 rpm. After centrifugation, 6 mL of extract underwent dSPE cleanup in parallel using either Carbon S or GCB sorbents. Final extracts were transferred to vials for GC/TQ analysis in dynamic MRM mode.

Used Instrumentation

• Agilent 8890 gas chromatograph with Agilent 7693A autosampler and multimode inlet
• Agilent 7000D triple quadrupole GC/MS in dynamic MRM (dMRM) mode
• J&W HP-5ms UI capillary columns (15 m × 0.25 mm, 0.25 μm)
• Geno/Grinder homogenizer and standard centrifuge

Main Results and Discussion

Matrix-matched calibration yielded R2 > 0.990 for all target pesticides. Cleanup with Carbon S achieved recoveries between 90 % and 110 % for 95 % of analytes at 5 ppb, compared to only 75 % with GCB. Notable improvements included hexachlorobenzene (69 % vs. 34 %) and chlorothalonil (93 % vs. 52 %). Both methods demonstrated precision better than 20 % RSD. Carbon S maintained effective pigment removal while reducing planar pesticide losses associated with GCB interactions.

Benefits and Practical Applications

• Enhanced recoveries for planar and non-planar pesticides across a broad analyte panel
• Efficient pigment removal to minimize matrix interferences and protect GC/MS flow paths
• Streamlined sample preparation compatible with high-throughput laboratories
• Robust quantitation for regulatory and quality control testing in food safety laboratories

Future Trends and Potential Applications

Further work may extend Carbon S cleanup to other challenging matrices such as leafy greens, spices, and fruits. Integration with high-resolution mass spectrometry and automated liquid handling can enhance throughput. Continued development of hybrid sorbents and greener extraction solvents will address emerging contaminants and sustainability goals in food analysis.

Conclusion

The validated QuEChERS GC/TQ workflow with Carbon S dSPE cleanup provides a reliable, high-recovery approach for multi-residue pesticide analysis in broccoli. Carbon S outperforms traditional GCB in maintaining analyte integrity and ensuring effective pigment removal, supporting robust food safety monitoring.

References

1. González-Curbelo, M. Á.; Evolution and Applications of the QuEChERS Method. Trends in Analytical Chemistry 2015, 71, 169–185.
2. Andrianova, A.; Zhao, L.; Five Keys to Unlock Maximum Performance in the Analysis of Over 200 Pesticides in Challenging Food Matrices by GC/MS/MS. Agilent Technologies Application Note 5994-4965EN, 2022.
3. Andrianova, A.; Quantitation of Pesticides in Strawberries at Tolerance Levels Established by the US EPA. Agilent Technologies Application Note 5994-0799EN, 2019.
4. Westland, J.; Analysis of Pesticides in Tomato and Kale on GC/MS/MS with Agilent Bond Elut QuEChERS High Pigment dSPE with Carbon S. Agilent Technologies Application Note 5994-5050EN, 2022.
5. Zhao, L.; Andrianova, A.; Determination of Over 3000 Pesticides in Cayenne Pepper. Agilent Technologies Application Note 5994-5630EN, 2023.