A Newly Modified QuEChERS Method for Multiresidue Pesticide Determination in Black Pepper Using LC/TQ

Significance of the topic

Black pepper is a high-value spice prone to pest and mold infestation in tropical climates. To ensure consumer safety and comply with international residue limits, sensitive multiresidue pesticide analysis is essential. Modified QuEChERS workflows coupled with advanced triple quadrupole LC/MS offer rapid, reliable screening of hundreds of pesticides in complex matrices.

Objectives and study overview

This study evaluated five QuEChERS-based cleanup strategies and dilution techniques for the simultaneous determination of 400 pesticides in black pepper using an Agilent 1290 Infinity II LC and 6495C triple quadrupole MS. Performance criteria included recovery, precision, matrix effects, calibration linearity, and sensitivity in accordance with SANTE 11312/2021.

Methodology

Pepper samples were homogenized and extracted with acetonitrile (acidified or neutral), followed by cleanup via: 1) dSPE (PSA/C18/GCB), 2) MeOH-dSPE, 3) Captiva EMR–GPD passthrough, 4) mixed-mode SPE (GCB/PSA), and 5) Bond Elut Plexa SPE plus dSPE. Dilution factors up to 10× were tested to mitigate matrix suppression.

Used instrumentation

• Agilent 1290 Infinity II LC with ZORBAX RRHD Eclipse Plus C18 column
• Agilent 6495C triple quadrupole MS operating in dynamic MRM
• Agilent QuEChERS extraction and cleanup kits (EN, dSPE, Captiva EMR–GPD, Plexa)
• MassHunter software for acquisition and Quantitative Analysis QQQ

Main results and discussion

Acidified ACN improved recoveries of acidic herbicides (e.g., flumetsulam) from <40% to >70%. A 10× dilution reduced matrix effects, yielding 40–120% suppression/enhancement for 69% of compounds. Procedure 2 (QuEChERS-MeOH/dSPE) balanced matrix removal and analyte recovery, with 93% of targets at 40–120% recovery and LOQs of 10 µg/kg for 84% of pesticides. Calibration curves were linear (R²≥0.99) for 95% of analytes. Robustness testing over 140 injections gave RSDr<5% for 78% of compounds.

Benefits and practical applications of the method

• High-throughput multiresidue screening
• Robust performance for routine QA/QC
• Reduced cleanup complexity and cost
• Adaptable to labs with varying instrument sensitivity

Future trends and potential applications

Further automation of cleanup, application to other challenging matrices, integration with high-resolution MS for non-target screening, and exploration of novel sorbent materials can expand analytical capabilities in food safety.

Conclusion

The optimized QuEChERS-MeOH/dSPE workflow paired with LC/TQ delivers reliable, reproducible analysis of 400 pesticides in black pepper, meeting regulatory requirements and supporting routine laboratory operations.

References

• Casado N., Morante-Zarcero S., Sierra I. Application of the QuEChERS Strategy as a Useful Sample Preparation Tool for the Multiresidue Determination of Pyrrolizidine Alkaloids in Food and Feed Samples: A Critical Overview. Appl. Sci. 2022, 12, 4325.
• Zou A. et al. Analysis of 510 Pesticides in Black Pepper. Agilent Technologies Application Note 5994-4768EN, 2022.
• Boonjob W. et al. Retention and Selectivity of Basic Drugs on Solid-Phase Extraction Sorbents: Application to Direct Determination of Β-Blockers in Urine. Anal. Bioanal. Chem. 2014, 406(17), 4207–4215.
• SANTE/11312/2021 Analytical Quality Control and Method Validation Procedures for Pesticide Residues Analysis in Food and Feed.