A sensitive and robust analytical solution for pesticide residues analysis in apple using GC-(AEI)-MS/MS

Significance of the Topic

Apples are a globally consumed fruit often treated with pesticides to maintain crop health and yield. Monitoring trace residues is crucial to protect consumer safety, ensure compliance with stringent MRLs set by the European Commission and FSSAI, and maintain trade standards in the international market.

Objectives and Study Overview

This study aimed to develop and validate a multi-residue analytical protocol for quantifying 211 pesticides in apples at trace levels. The method was optimized to meet EU SANTE/11813/2017 and FSSAI regulatory requirements, focusing on sensitivity, robustness, and throughput for routine food safety testing laboratories.

Methodology

The sample preparation employed cryogenic milling to prevent analyte degradation, followed by a QuEChERS AOAC 2007.01 extraction and dispersive-SPE clean-up. Matrix-matched calibration standards (0.0001–0.050 mg/kg) were prepared to correct for over 20% matrix enhancement. Data acquisition utilized timed SRM transitions, ensuring at least 12 data points per peak for precise quantitation. Validation parameters included ion ratio tolerance (±30%), retention time window (±0.1 min), linearity (R² > 0.99), recoveries (70–120%), and precision (<20% RSD).

Used Instrumentation

• Thermo Scientific TRACE 1310 GC with TriPlus RSH autosampler
• Thermo Scientific TraceGOLD TG-5SIL MS column (30 m × 0.25 mm ID, 0.25 µm)
• Thermo Scientific TSQ 9000 triple quadrupole MS with Advanced Electron Ionization (AEI) source
• Helium carrier gas (99.999%), splitless injection (1 µL)
• Chromeleon 7.2 Chromatography Data System

Main Results and Discussion

The method achieved limits of quantitation of 0.001 mg/kg for more than 95% of target compounds, well below the lowest MRL of 0.01 mg/kg. Linearity was excellent (R² > 0.99, residuals <±20%), with typical recoveries between 70% and 120% and RSDs under 15% across low (0.001 mg/kg), intermediate (0.005 mg/kg), and high (0.010 mg/kg) levels. Key degradation-prone analytes (captan, captafol, folpet) showed >70% recovery due to cryogenic homogenization. Ion ratio and retention time repeatability remained within SANTE criteria over 100 consecutive injections without maintenance, demonstrating exceptional robustness.

Benefits and Practical Applications

• High sensitivity and low LOQs support compliance with EU and FSSAI MRLs.
• Robust performance enables over 40 daily injections with <10% area variation.
• Streamlined workflow integrates extraction, cleanup, and GC-MS/MS analysis for high throughput.
• Matrix-matched calibration ensures accurate quantitation despite complex apple matrices.

Future Trends and Possibilities

• Expansion of target analyte lists to emerging pesticide classes and metabolites.
• Integration of machine learning for automated data review and anomaly detection.
• Adoption of miniaturized and green sample-preparation techniques to reduce solvent use.
• Development of portable MS systems for on-site residue screening.

Conclusion

The combination of cryogenic milling, QuEChERS extraction, and GC-AEI-MS/MS on the TSQ 9000 platform delivers a sensitive, precise, and reliable method for multi-residue pesticide analysis in apples. The validated workflow meets international regulatory standards and is well suited for routine food safety monitoring.

References

1. WorldAtlas. "Top Apple Producing Countries in the World." 2019.
2. Central Insecticide Board and Registration Committee (CIBRC). "Registered Insecticides/Pesticides under the Insecticides Act, 1968." May 2019.
3. European Commission. EU Pesticides Database. Retrieved 2019.
4. Food Safety and Standards Authority of India. "Compendium of Contaminants and Toxins Regulations." May 2019.
5. AOAC Official Method 2007.01. "Pesticide Residues in Foods by Acetonitrile Extraction and Partitioning with Magnesium Sulfate." 2007.
6. European Commission. SANTE/11813/2017 Guidance Document on Pesticide Residue Analysis.
7. Fussell RJ, Hetmanski MT, Colyer A, Caldow M, Smith F, Findlay D. "Stability of Pesticides during Cryogenic Processing of Fruits and Vegetables." Food Additives and Contaminants, 2007;24:1247–1256.
8. EURL‐SRM. "Stability of Captan, Folpet and Their Degradation Products." 2016.