Determination of pesticide residues in traditional Chinese medicinal materials Milkvetch Root

Importance of the topic

Traditional Chinese medicinal herbs like Milkvetch Root are prone to pesticide contamination due to disease and pest control during cultivation. Residual pesticides can affect human health and limit international acceptance of herbal products. A robust, sensitive multi-residue analysis method is essential to ensure the safety and quality of these botanicals.

Objectives and study overview

This work aimed to develop and validate a triple quadrupole GC-MS method for simultaneous determination of 41 pesticide residues in Milkvetch Root. The method was designed to meet requirements of the Chinese Pharmacopoeia and to provide high sensitivity, accuracy and reproducibility for routine quality control.

Methodology and instrumentation

Sample preparation involved:

• Weighing 5 g of powdered Milkvetch Root
• Extracting with 20 mL dichloromethane by vortexing and 30 min ultrasonication
• Centrifugation at 3000 rpm for 30 min
• Cleanup on a florisil column eluted with n-hexane/acetone (85/15)
• Concentration to 1 mL and filtration prior to analysis

Instrumental analysis was performed on a Shimadzu GCMS-TQ8040 triple quadrupole GC-MS with:

• Rxi-5 MS column (30 m × 0.25 mm × 0.25 µm)
• Oven program: 50 °C (1 min) to 125 °C at 25 °C/min, then to 300 °C at 10 °C/min (3.5 min)
• Splitless injection at 250 °C
• Carrier gas linear velocity mode (47.2 cm/s), argon CID gas
• Interface and ion source temperatures at 250 °C and 200 °C respectively

Main results and discussion

Calibration curves for all 41 pesticides showed excellent linearity over 1–500 µg/L with correlation coefficients above 0.999. Limits of detection (S/N=3) were mostly below 0.001 mg/L. Precision, assessed by six replicate injections of a 0.01 mg/L standard, yielded relative standard deviations below 5%. Recovery tests at 0.002 mg/kg spiking level in commercial Milkvetch Root gave rates from 74.5% to 124.1%. Analysis of a market sample demonstrated no detectable pesticide residues.

Benefits and practical applications of the method

• High-throughput multi-residue screening of 41 pesticides
• Superior sensitivity and accuracy to meet regulatory standards
• Rapid sample preparation and clean-up protocol
• Suitable for routine quality control in research and industry

Future trends and potential applications

Advances may include expanding the pesticide panel, integrating high-resolution mass spectrometry for non-target screening, and adapting the workflow to other herbal matrices. Automation of sample clean-up and data processing can further improve throughput and reproducibility.

Conclusion

A validated GC-MS/MS method using the Shimadzu GCMS-TQ8040 was established for sensitive, accurate determination of 41 pesticide residues in Milkvetch Root. The method meets pharmacopoeial requirements, demonstrates strong linearity, low detection limits, acceptable recoveries and precision, and is ready for routine application in herbal medicine quality assurance.

References

• No external references were cited in the source document