Confident analysis of ultra-trace pesticides residues in baby food using GC- triple quadrupole MS

Importance of the topic

Baby foods must meet stringent safety standards due to the vulnerability of infants to pesticide exposure. Analytical methods capable of detecting ultra-trace levels of pesticide residues ensure compliance with regulatory maximum residue levels and protect public health.

Objectives and study overview

This study aimed to develop and validate a robust gas chromatography triple quadrupole mass spectrometry method for the simultaneous detection of over 200 GC-amenable pesticides in baby food matrices at ultra-trace levels, following SANTE/11312/2021 guidelines. The method performance was assessed in terms of sensitivity, selectivity, linearity, accuracy, precision, and long-term robustness.

Methodology

• Sample preparation: Citrate-buffered QuEChERS extraction of blank and spiked baby food samples with acidified acetonitrile, followed by cleanup using magnesium sulfate, sodium chloride and PSA sorbent.
• Calibration: Matrix-matched standards prepared at 0.05 to 500 micrograms per kilogram in duplicate to evaluate linearity with R squared values above 0.99 and response factor repeatability below 20 percent.
• Detection: Timed SRM acquisition monitoring two product ions per pesticide, with retention time tolerance of plus or minus 0.1 minute and ion ratio acceptance within 30 percent, in accordance with SANTE criteria.
• Detection limits: Instrument detection limits determined by spiking matrix extracts at 0.08 to 3 micrograms per kilogram and applying a one-tailed Student’s t-test, yielding IDLs of 6 to 650 femtograms on column (average 0.073 micrograms per kilogram).
• Robustness testing: Continuous injection of 500 randomized matrix extracts spiked at 10 micrograms per kilogram over four weeks, with scheduled maintenance of the PTV injector liner, septum replacement, column trimming and periodic QC injections at 3 micrograms per kilogram.

Used instrumentation

• Thermo Scientific TRACE 1610 gas chromatograph with programmable temperature vaporization injector
• Thermo Scientific TSQ 9610 triple quadrupole mass spectrometer with NeverVent AEI ion source and XLXR electron multiplier detector
• Thermo Scientific AI/AS 1610 liquid autosampler
• Thermo Scientific Chromeleon chromatography data system version 7.3

Main results and discussion

• Linearity and dynamic range: All analytes exhibited calibration curves with R squared above 0.99 across the full range.
• Recovery and precision: Mean recoveries between 70 and 120 percent and repeatability RSD below 10 percent at 3 micrograms per kilogram in spiked matrices.
• Sensitivity: Detection limits from 0.006 to 0.65 micrograms per kilogram, surpassing EU limits for baby foods.
• Instrument robustness: Stable normalized peak responses and ion ratios over 500 injections, enabled by NeverVent technology allowing ion source maintenance without breaking vacuum.

Benefits and practical application

This method supports high-throughput multi-residue analysis with minimal sample preparation, delivering rapid, accurate and sensitive results to meet regulatory requirements and safeguard infant health. It is fully suited for routine QA and QC laboratories.

Future trends and opportunities

• Automation of sample cleanup and data processing to increase laboratory throughput.
• Integration with high-resolution mass spectrometry for non-targeted screening and retrospective analysis.
• Development of miniaturized and solvent-minimizing extraction techniques for greener workflows.
• Adoption of ambient ionization methods for direct surface analysis of food products.
• Use of chemometric and machine learning tools for advanced data interpretation and trend monitoring.

Conclusion

The presented GC-MS/MS workflow using the TSQ 9610 system combined with QuEChERS extraction fully complies with SANTE/11312/2021 criteria for ultra-trace pesticide analysis in baby foods. It achieves excellent sensitivity, selectivity, accuracy, precision and long-term robustness, making it a reliable tool for routine regulatory monitoring.

References

• Analytical quality control and method validation procedures for pesticide residues analysis in food and feed. SANTE/11312/2021, implemented January 1, 2022.