Ultra low level quantification of pesticides in baby foods using an advanced triple quadrupole GC-MS/MS system

Importance of the topic

The accurate measurement of pesticide residues in baby foods is critical to ensure the safety of infants and young children, who are particularly vulnerable to low‐level chemical exposures. Regulatory authorities in the European Union impose maximum residue limits (MRLs) and lower detection thresholds for harmful pesticides in baby foods, necessitating highly sensitive, selective, and robust analytical approaches for routine monitoring.

Goal and Study Overview

This study evaluated the quantitative performance of the Thermo Scientific TSQ 9000 triple quadrupole GC‐MS/MS system equipped with an Advanced Electron Ionization (AEI) source in combination with citric QuEChERS sample preparation for the simultaneous determination of over 200 pesticide residues in multi‐ingredient baby foods at ultra‐low levels (down to 0.025 µg/kg). Method suitability was assessed in terms of recovery, sensitivity, linearity, selectivity, and long‐term robustness according to EU SANTE/11813/2017 guidelines.

Methodology and Instrumentation

Sample Preparation and Clean-up

• 10 g homogenized baby food (carrot/potato or apple/pear/banana) extracted with 10 mL acetonitrile and citrate‐buffered QuEChERS salts.
• Dispersive SPE clean-up using HyperSep MgSO₄, PSA and graphitized carbon black tailored to each matrix.
• Matrix-matched calibration spans 0.025–250 µg/kg with 211 pesticides.

GC-MS/MS Analysis

• Thermo Scientific TRACE 1310 GC with TRACEGOLD TG-5SilMS column and PTV injection.
• TSQ 9000 triple quadrupole MS with AEI source, timed-SRM acquisition, unit mass resolution (0.7 Da Q1/Q3), SmartTune auto-tuning.
• Chromeleon CDS software for instrument control, data processing, and SANTE compliance reporting.

Main Results and Discussion

Recovery and Precision

• At spiking levels of 1, 2.5 and 10 µg/kg, over 97% of pesticides showed recoveries within 70–120% and RSDs below 15% in both matrices.

Sensitivity and Linearity

• Instrumental detection limits (IDLs) ranged from 5 fg to 2 pg on-column; >95% of compounds had IDLs below 500 fg (equivalent to 0.5 µg/kg).
• Over 90% of pesticides met SANTE identification criteria at concentrations below 0.5 µg/kg, with 10% detectable at 0.025 µg/kg.
• Calibration curves displayed R² > 0.990 and response factor RSD < 20% across five orders of magnitude.

Robustness

• Approximately 400 consecutive injections of real sample extracts at 10 µg/kg exhibited stable peak areas, shapes, and qualifier ion ratios within ±30% of expected values.
• Minimal maintenance: PTV liners and septa replaced every 100 injections, source cleaned only once.

Benefits and Practical Applications

The combined use of rapid QuEChERS preparation, AEI‐enhanced GC-MS/MS sensitivity, and intelligent software control provides a highly productive workflow for regulatory laboratories. Ultra‐trace detection capabilities allow dilution of extracts to reduce matrix effects and maintenance while maintaining full compliance with stringent baby food residue limits.

Future Trends and Potential Applications

Advances in ion source designs and chromatographic materials will further lower detection limits and widen the scope of analytes. Integration with high-throughput automation and enhanced data analytics will support large‐scale monitoring programs across diverse food matrices. Continuous updates to residue definitions and MRLs will drive method adaptations to emerging pesticide chemistries.

Conclusion

The TSQ 9000 triple quadrupole GC-MS/MS system with AEI source, coupled to optimized QuEChERS extraction and Chromeleon CDS software, delivers exceptional sensitivity, selectivity, linearity, and robustness for ultra-low level pesticide quantification in baby foods. This solution meets EU regulatory requirements and offers a reliable, high-throughput workflow for routine safety testing.

Reference

• European Commission. Commission Directive 2006/125/EC on maximum residue limits for pesticides in infant foods.
• European Commission. SANTE/11813/2017 Guidance Document on analytical quality control and method validation for pesticide residues.
• Belmonte Valles N., Retamal M., Martínez-Uróz M.A., Mezcua M., Fernández-Alba A.R., de Kok A. Analyst 2012, 137(10), 2513–2520.
• Thermo Fisher Scientific. Application Note AN10586: Ultra low level quantification of pesticides in baby foods using TSQ 9000 GC-MS/MS.