Method for the determination of 313 Residual Pesticides in Black tea using LCMS-8045 and GCMS-TQ8040 NX

Importance of the Topic

Tea is one of the most widely consumed beverages worldwide, and ensuring its safety is critical due to the routine use of diverse pesticides in tea cultivation. Regulatory bodies such as the EU, FSSAI, APEDA and Japan have set stringent maximum residue limits (MRLs) for over 400 pesticides, driving the need for sensitive, high-throughput analytical methods capable of screening hundreds of compounds simultaneously in complex matrices like black tea.

Objectives and Study Overview

This study aimed to develop and validate a unified multiclass, multi-residue protocol for the quantification of 313 pesticides in black tea using ultra-fast LC-MS/MS and GC-MS/MS. Key goals included achieving low limits of quantification (LOQs), robust recovery and precision across a broad compound library, while minimizing matrix interference and analysis time to support routine QA/QC workflows.

Methodology and Instrumentation

A modified QuEChERS extraction was employed for simultaneous isolation of 203 pesticides for LC-MS/MS and 131 pesticides for GC-MS/MS (with 21 overlapping analytes). Acidified acetonitrile or ethyl acetate mixtures, combined with salts and dispersive sorbents (PSA, C18, GCB, MgSO₄, CaCl₂), provided cleanup and minimized matrix effects before evaporation and reconstitution.

Instrumentation:

• LC-MS/MS: Shimadzu LCMS-8045 coupled to Nexera X2. Column: Shim-pack XR-ODS II (150×3.0 mm, 2.2 µm). Mobile phases: 2 mM ammonium formate with 0.002% formic acid in water and methanol. Flow rate: 0.4 mL/min; injection volume: 10 µL; run time: 21 min.
• GC-MS/MS: Shimadzu GCMS-TQ8040 NX with AOC-20i + s auto-injector, SH-I-5Sil MS column (30 m×0.25 mm, 0.25 µm). Carrier gas: He at 36.5 cm/s. Injector: splitless; volume: 1 µL; run time: 25 min.
• Data Processing: LabSolutions Insight with Shimadzu Method Package Ver.3 and Smart Pesticides Database Ver.2 for rapid MRM optimization and validation.

Key Results and Discussion

Validation followed SANTE/12682/2019 guidelines. Specificity was confirmed with blank matrices showing <30% of reporting levels. Linearity (R²>0.98) was achieved over 1–50 µg/L (LC-MS/MS) and 1–15 µg/L (GC-MS/MS). LOQs of 10 µg/kg were attained for 198 analytes by LC-MS/MS and 81 by GC-MS/MS; a subset required LOQs of 20–40 µg/kg. Mean recoveries at LOQ ranged from 70–120% for 169 LC-MS/MS and 119 GC-MS/MS compounds, with repeatability and reproducibility (RSDr, RSDR) below 20% for all targets. The method demonstrated robust precision (<20% RSD) and minimal matrix suppression across 6 matrix-matched replicates.

Benefits and Practical Applications

• High sensitivity and broad pesticide coverage enable compliance monitoring in tea and similar complex food matrices.
• Short analysis times and reduced flow/injection volumes extend column life and support high sample throughput.
• Streamlined sample prep reduces labor and solvent usage while maintaining low LOQs.
• Automated method packages accelerate instrument setup and ensure consistent performance across laboratories.

Future Trends and Potential Applications

Advances may include integration of high-resolution mass spectrometry for non-target screening, further miniaturization of sample prep, and application of machine learning for data interpretation. Expansion to other beverages and food commodities, as well as adoption of cloud-based data platforms, will enhance real-time monitoring and regulatory compliance.

Conclusion

This validated protocol leveraging Shimadzu’s LC-MS/MS and GC-MS/MS platforms delivers a rapid, reliable and comprehensive solution for multi-residue pesticide analysis in black tea. It meets international regulatory requirements and supports high-throughput laboratory environments, ensuring consumer safety and product quality.

References

• Anastassiades M., Lehotay S. J., Štajnbaher D., Schenck F. J. Fast and Easy Multiresidue Method Employing Acetonitrile Extraction/Partitioning and “Dispersive Solid-Phase Extraction” for the Determination of Pesticide Residues in Produce. J. AOAC Int., 86, 412–431 (2003).
• European Commission. Guidance document on analytical quality control and method validation procedures for pesticide residues and analysis in food and feed. SANTE/12682/2019.