Determination of Pesticide Residues in Rice-Based Baby Food using GC-MS/MS with APGC™ after Extraction and Clean Up using QuEChERS

Importance of the Topic

Infant and young children foods require stringent monitoring of pesticide residues due to their vulnerability and strict regulatory limits. Rice-based baby foods, in particular, demand sensitive and reliable analytical methods to ensure compliance with low maximum residue levels (MRLs) set by EU regulations.

Objectives and Study Overview

This study aimed to develop and validate a robust method for quantifying 166 pesticides and metabolites in rice-based baby food at and below regulatory MRLs. The method leverages a QuEChERS extraction coupled with GC-MS/MS and atmospheric pressure gas chromatography (APGC) ionization on a Xevo TQ-XS platform.

Methodology and Instrumentation

The sample preparation followed a standard QuEChERS protocol with dSPE cleanup, including:

• Weighing and hydrating 5 g of sample
• Extraction with acetonitrile and QuEChERS salts
• Centrifugation, freezing, and dispersive SPE cleanup with MgSO₄ and PSA
• Formic acid addition and 1:1 dilution with acetonitrile for analysis

Instrumentation details:

• GC Conditions: Standard gas chromatography setup
• MS System: Xevo TQ-XS tandem mass spectrometer
• Ionization: APGC 2.0 with water modifier at 150 °C
• Transfer line temperature: 280 °C; corona current: 2.0 µA
• Auxiliary and cone gas flows: 200 L/hr and 265 L/hr, respectively

Main Results and Discussion

The method demonstrated exceptional sensitivity, with instrument detection limits typically at or below 0.0003 mg/kg. Of 166 analytes, all but one were detectable at 0.0003 mg/kg; thiometon’s LOD was 0.005 mg/kg. Key performance metrics include:

• Retention time stability within ±0.1 min and ion ratio compliance for 94% of analytes
• Recoveries at 0.0005 mg/kg and 0.001 mg/kg spikes: 90% and 92% of pesticides met the 70–120% SANTE criteria
• Repeatability (RSDr) ≤20% for 96% of pesticides at the lower spike and 100% at the higher level
• Calibration residuals within ±20% and r² >0.98 for 95% of analytes

Benefits and Practical Applications of the Method

This validated procedure offers:

• Ultra-low detection limits adequate for strict infant food regulations
• Streamlined workflow without solvent exchange or large-volume injections
• Robust compliance with EU guidelines for routine quality control
• Wide applicability to other cereal-based matrices and residue monitoring

Future Trends and Applications

Potential developments include:

• Extension to additional food matrices such as wheat and maize-based products
• Integration with automated sample-preparation systems for higher throughput
• Adoption of emerging ionization sources to expand analyte coverage
• Coupling with high-resolution mass spectrometry for non-targeted screening

Conclusion

The method provides a sensitive, accurate, and efficient approach for monitoring a broad range of pesticides in rice-based baby food, meeting stringent regulatory requirements.

Reference

1. Commission Directive 2006/125/EC on processed cereal-based foods and baby foods
2. Commission Delegated Regulation (EU) 2021/1041 amending pesticide requirements in infant formula
3. EURL-CF Validation Report 31A, 2019
4. SANTE/11313/2021 Guidance on Analytical Quality Control and Method Validation