LC-MS/MS analysis of polar pesticides in honey with QuPPe extraction

Importance of the Topic

Polar ionic pesticides such as glyphosate, AMPA, chlorate and perchlorate frequently contaminate food products but are poorly retained in standard reverse-phase LC and often escape generic multi-residue screening. Regulatory limits for these compounds in foods can be as low as 10 µg/kg, demanding highly sensitive, selective and robust analytical workflows for routine monitoring.

Objectives and Study Overview

The study aimed to establish a fast and reliable LC-MS/MS method for quantifying multiple polar pesticides in honey using the QuPPe extraction protocol and separation on a porous graphitic carbon column.

Methodology and Instrumentation

• Sample Preparation: QuPPe (Quick Polar Pesticides) extraction of honey to isolate target analytes from complex sugars and matrix interferences.
• Chromatography: Thermo UltiMate 3400 RSLC with Hypercarb 2.1 × 100 mm, 5 µm column; mobile phases: A) 1% acetic acid in water with 5% methanol, B) 1% acetic acid in methanol; gradient from 100% A to 10% A over 19 min, flow rates 0.2–0.4 mL/min, column at 40 °C, 5 µL injection.
• Mass Spectrometry: Thermo TSQ Quantiva triple quadrupole with heated electrospray ionization in negative mode; SRM acquisition of characteristic precursor-to-product ion transitions; mass calibration performed with Extended Mass Range solution containing 14 compounds (69–2800 m/z).
• Data Analysis: TraceFinder software for quantitation, calibration weighting 1/x, linear dynamic range assessed.

Main Results and Discussion

Instrumental limits of quantification in solvent were sub-ppb for most analytes. In honey extracts, matrix suppression raised LOQs to the 2–10 µg/kg range, still below EU maximum residues limits. Calibration curves from 5 to 500 µg/kg showed excellent linearity (R2 > 0.99). Chromatographic resolution of glyphosate and AMPA was clearly demonstrated with distinct quantifier and qualifier ions. System robustness was confirmed by over 500 consecutive injections without capillary clogging; a simple hot water/methanol cleaning restored performance without venting the vacuum.

Benefits and Practical Applications

• High sensitivity and selectivity for polar pesticides in challenging matrices.
• Meets or exceeds EU regulatory requirements for food safety monitoring.
• High throughput enabled by robust TSQ Quantiva system and straightforward cleaning.
• Suitable for routine QA/QC in food laboratories, ensuring consumer safety.

Future Trends and Potential Applications

Future efforts may broaden the target list to include emerging polar contaminants, adapt the workflow to other food or environmental matrices, integrate high-resolution mass spectrometry for non-target screening, and automate sample preparation and data processing to increase throughput and reproducibility.

Conclusion

The QuPPe-based extraction coupled with Hypercarb LC-MS/MS on a TSQ Quantiva system provides a rapid, sensitive and robust approach for analyzing polar pesticide residues in honey. The method delivers regulatory-compliant quantitation with minimal downtime and is well suited for routine food safety monitoring.

References

• European Reference Laboratory for Single Residue Methods. Quick Polar Pesticides (QuPPe) Method; 2016.
• European Commission. Regulation (EC) No 396/2005 on maximum residue levels of pesticides in food and feed; 2005.