Application of SFC-MS/MS for the Quantifcation of Highly Polar Pesticides in a Range of Food Samples

Significance of the Topic

The accurate quantification of highly polar pesticides in food is critical for ensuring consumer safety and meeting regulatory limits. Traditional multi-residue methods often struggle with polar analytes, necessitating specialized approaches. Supercritical fluid chromatography coupled with tandem mass spectrometry (SFC-MS/MS) offers a promising alternative by combining efficient separation with sensitive detection of a broad chemical space.

Objectives and Study Overview

This study aimed to develop and validate an SFC-MS/MS method for simultaneous analysis of a panel of highly polar pesticides in various food matrices (pepper, flaxseed and lemon). Food extracts prepared by the QuPPe protocol were spiked with target compounds and directly injected, evaluating chromatographic behavior, quantitative performance and matrix effects.

Methodology and Instrumentation

The analytical system comprised a Shimadzu Nexera UC SFC platform and LCMS-8060 mass spectrometer. Key parameters included:

• Stationary phase: Restek Ultra Silica (150 × 2.1 mm, 3 µm)
• Mobile phase A: CO₂
• Mobile phase B: acetonitrile + 0.5% formic acid + 10 mM ammonium formate + 6% water
• Make-up solvent (pump D): methanol at 0.2 mL/min
• Column temperature: 50 °C; flow rate: 0.8 mL/min (0.6 mL/min at 13–22 min)
• Ionization: heated electrospray (HESI) at 300 °C interface, 350 °C block, 250 °C desolvation line
• MRM acquisition: dwell time 3 ms, pause time 1 ms, scan speed 15,000 u/s

Main Results and Discussion

Method development demonstrated that adding approximately 6% water to the organic modifier significantly improved peak shape and retention of polar analytes. A dynamic ternary gradient of CO₂, acetonitrile/water and aqueous ammonium formate enabled baseline separation of analytes spanning log P values from –3.47 to +1.96.

Calibration in lemon and flaxseed matrices (10–200 ppb) yielded linear regression coefficients (R²) ≥0.996 and relative standard deviations below 11% for all targets. Stable isotope-labelled internal standards corrected for matrix effects, providing consistent quantitation across diverse sample types.

Benefits and Practical Applications

• Robust quantitation of challenging polar pesticides at low ppb levels
• Reduced sample preparation steps by direct injection of QuPPe extracts
• Wide applicability across different food matrices with minimal method adjustments
• Enhanced throughput and sensitivity compared to conventional LC-MS/MS techniques

Future Trends and Potential Applications

Emerging directions include expansion of the analyte panel to cover additional polar residues, integration with high-resolution mass spectrometry for non-target screening, and method transfer to routine regulatory laboratories. Advances in column chemistries and solvent blending technologies will further refine selectivity and robustness.

Conclusion

The optimized SFC-MS/MS workflow delivers a versatile and reliable platform for multi-residue analysis of highly polar pesticides in food. Incorporating water into the SFC gradient and using stable isotope internal standards ensures accurate quantitation across matrices, meeting the growing demands of food safety monitoring.

References

• Anastassiades M, et al. QuPPe of EURL-SRM, Version 9.1; European Union Reference Laboratories for Residues of Pesticides; 2016.
• Baker D, Barnes A, Titman C, Horner J, Loftus N. Application of SFC-MS/MS for the Quantification of Highly Polar Pesticides in a Range of Food Samples. ASMS 2017, MP-195.