Multi-Residue Pesticide Analysis in Herbal Juices using GC-MS/MS

Significance of the Topic

Herbal juices such as Aloe vera and Amla are increasingly consumed for their health benefits, yet they may carry pesticide residues from cultivation. Reliable multi-residue analysis is critical to ensure compliance with regulatory maximum residue levels (MRLs) and to protect consumer safety. Advanced GC-MS/MS approaches combined with streamlined sample preparation protocols enable rapid, high-throughput screening of complex matrices.

Aims and Overview of the Study

The study aimed to develop and validate a multi-residue method for over 200 pesticides in Aloe vera and Amla juices. Key goals included achieving rapid chromatographic separation (11-minute run), high selectivity, low limits of quantitation (LOQs), and robust performance across two challenging herbal matrices.

Methodology and Instrumentation

• Sample Preparation: QuEChERS extraction of 10 mL homogenized juice with acetonitrile and NaCl, followed by dispersive SPE cleanup using PSA and GCB.
• Chromatography: TRACE 1310 GC with splitless injector; TG-5SilMS column; oven program from 65 °C to 320 °C at 30 °C/min.
• Detection: TSQ 8000 Evo triple quadrupole GC-MS/MS operated in timed-SRM mode, three transitions per analyte (one quantifier, two qualifiers), optimized collision energies.
• Data Processing: Thermo Scientific TraceFinder software for automated method setup, peak integration, and reporting.

Main Results and Discussion

• Linearity: Calibration curves in matrix showed R² > 0.98 for all analytes, with negligible false positives (< 1%).
• Sensitivity: LOQs ≤ 1 µg/kg for 152 compounds; 75 compounds at 1–5 µg/kg; 20 compounds at 5–10 µg/kg. Matrix enhancement was moderate, more pronounced in Aloe vera.
• Recovery and Precision: Mean recoveries between 70–120% at spike levels of 2, 5, and 10 µg/kg; RSDs < 20% in both juice matrices.
• Throughput: Automatic timed-SRM acquisition eliminated manual segment optimization, providing uniform cycle times and maximized dwell times even with over 200 analytes.

Benefits and Practical Applications

• Comprehensive Coverage: Single-injection analysis of a broad pesticide panel meets regulatory and routine monitoring needs.
• Speed and Efficiency: Short run time and automated data processing support high sample throughput in quality control laboratories.
• Robustness: Effective cleanup and high selectivity minimize matrix interferences, ensuring reliable quantitation at trace levels.

Future Trends and Possibilities

• Integration with High-Resolution MS: Combining GC-Orbitrap or time-of-flight detectors for non-target screening and retrospective data analysis.
• Automation and Miniaturization: Online QuEChERS, microfluidic sample preparation, and robotic workflows to further reduce labor and solvent use.
• Advanced Data Analytics: Incorporation of machine learning for automated anomaly detection, improved confirmation of low-level residues, and predictive trend analysis.
• Multi-Matrix Extension: Adapting the method to other beverages, botanical extracts, and complex food products.

Conclusion

The validated QuEChERS-GC-MS/MS method using the TSQ 8000 Evo demonstrates excellent sensitivity, selectivity, and throughput for multi-residue pesticide analysis in herbal juices. Its robust performance supports regulatory compliance and routine quality control, while future enhancements in automation and high-resolution detection promise to broaden its applicability.

References

• Codex Alimentarius Commission. Pesticide Residue Limits for Food and Feed.
• Commission Regulation (EC) No 396/2005 on MRLs of Pesticides.
• Anastassiades M. et al. (2003). Fast QuEChERS for Multiresidue Pesticide Analysis. J. Agric. Food Chem. 51: 17–24.
• Kellmann M. et al. (2009). Full Scan MS in Qualitative and Quantitative Residue Analysis. J. Am. Soc. Mass Spectrom. 20: 1464–1476.
• Thermo Scientific Application Note 10449. Fast Screening and Quantification of Pesticide Residues in Baby Food. 2015.