Screening of Pesticide Residues in Traditional Chinese Medicine with the Agilent Intuvo 9000 GC

Significance of the Topic

The presence of pesticide residues in Traditional Chinese Medicine (TCM) can compromise consumer safety and regulatory compliance. Reliable screening methods are essential to detect banned compounds and their metabolites across diverse plant-derived matrices, ensuring that TCM products meet pharmacopeial standards and protect public health.

Objectives and Study Overview

This study implemented the Chinese Pharmacopoeia 2020 Method No. 5 to quantify 30 banned pesticides and metabolites in seven TCM matrices. Key objectives:

• Optimize QuEChERS extraction and dispersive cleanup for broad-spectrum analyte recovery
• Evaluate Agilent Intuvo 9000 GC with midcolumn backflush paired with a 7000 triple quadrupole MS
• Assess method performance—linearity, precision and recovery—in wolfberry, licorice, angelica roots, celosia seeds, mulberry leaf, cassia seeds and Sichuan bulb of fritillary

Methodology

Samples (3 g each) were extracted with acetonitrile using the QuEChERS approach. Two dispersive cleanup kits (2048 and 5156) were compared; kit 5156 (C18, PSA, MgSO₄) was selected for its superior recovery (72.7–124.6 %) and pigment removal. Matrix-matched calibration standards spanned 4–200 ng/mL over six to seven levels. Recoveries were evaluated at low and high spike levels in each matrix.

Used Instrumentation

• Agilent Intuvo 9000 GC with D2-MS midcolumn backflush Flow Chip
• Agilent 7000 Triple Quadrupole GC/MS
• Agilent 7650A automatic liquid sampler

Chromatographic separation employed two Agilent J&W DB-17 columns (15 m × 0.25 mm, 0.25 µm) in series under constant helium flow. The GC oven ramp (80 °C to 300 °C) achieved separation and backflush in 26.8 min, reducing run time by 40 % relative to the pharmacopeial method.

Key Results and Discussion

• Cleanup optimization: Dispersive kit 5156 improved chlordimeform recovery from 34 % to 95.8 %
• Precision: At 50 ng/mL in three matrices, 21 compounds showed RSD ≤5 %; a few analytes exhibited higher RSDs (up to 16 %) dependent on matrix effects
• Linearity: Matrix-matched curves returned R² = 0.995–0.998 for all targets
• Short GC program: Enhanced signal-to-noise and peak shape over the longer constant-pressure method
• Real samples: No target residues exceeded LOQ in cassia seeds, celosia seeds, mulberry leaf or Sichuan bulb of fritillary

Benefits and Practical Applications

This workflow supports high-throughput residue screening in complex botanical matrices. Midcolumn backflush and replaceable guard chips prevent carryover and protect columns. Optimized cleanup kits ensure reliable recovery across various plant tissues.

Future Trends and Possibilities

Advances may include expanding multi-residue panels, coupling high-resolution MS for non-target screening, automating sample preparation, and integrating data-driven quality control for real-time regulatory monitoring.

Conclusion

The combined Agilent Intuvo 9000 GC with backflush and triple quadrupole MS, paired with an optimized QuEChERS cleanup, delivers robust, rapid and sensitive screening of banned pesticides in TCM, complying with Chinese Pharmacopoeia requirements while boosting laboratory throughput.

Reference

Method No. 5: Multi-residue determination of banned pesticides in medicinal materials (plants), Chinese Pharmacopoeia 2020.