Multi-Residue Pesticide Analysis in Ginseng Powder: Optimized Cleanup After QuEChERS Extraction for UPLC-MS/MS And GC-MS/MS Analysis

Significance of the Topic

Multi-residue analysis of pesticides in herbal supplements such as ginseng powder is critical for ensuring consumer safety and regulatory compliance. Dried, resinous matrices pose challenges for conventional extraction and cleanup workflows, increasing the risk of matrix interferences, instrument fouling, and downtime. An optimized sample preparation strategy tailored to ginseng ensures reliable quantitation of a broad spectrum of pesticide residues while minimizing maintenance and maximizing laboratory throughput.

Objectives and Study Overview

This study aimed to develop and validate a streamlined workflow for the simultaneous determination of base/neutral pesticides in American ginseng powder. Key goals included:

• Achieving high recovery and reproducibility for over 40 target compounds at 10–100 ppb levels.
• Implementing rapid QuEChERS extraction followed by two cleanup paths: dispersive SPE (dSPE) for UPLC-MS/MS and cartridge SPE for GC-MS/MS.
• Demonstrating a single Xevo TQ-S mass spectrometer’s versatility with both electrospray and atmospheric pressure GC ionization.

Methodology and Instrumentation

Sample Preparation:

• Weighed 2 g ginseng powder, hydrated with 10 mL water for 30 min, then extracted with 10 mL acetonitrile and QuEChERS salts (DisQuE pouch).
• Aliquots of supernatant underwent either dSPE cleanup (MgSO₄/PSA/C18 with graphite carbon black) for LC-MS or SPE cleanup (PSA/carbon cartridge, MgSO₄ top) for GC-MS.

UPLC-MS/MS Conditions:

• ACQUITY UPLC I-Class with BEH C18 column (2.1×100 mm, 1.7 µm), 0.45 mL/min gradient (10 mM ammonium acetate in water/methanol, pH 5.0), 45 °C, 5 µL injection.
• Xevo TQ-S in ESI+/- mode with optimized cone and collision settings for >30 pesticides.

GC-MS/MS (APGC) Conditions:

• Agilent 7890 GC with J&W DB-5 MS column (30 m×0.25 mm×0.25 µm), helium 2.0 mL/min, splitless injection.
• Atmospheric pressure GC source on Xevo TQ-S, API+ mode, corona 2.2 µA, probe 450 °C, optimized collision energy for 15 compounds.

Main Results and Discussion

dSPE-LC-MS/MS recoveries ranged from 79% to 124% (RSD < 25%) for 30+ pesticides at 10 and 100 ppb. SPE-APGC-MS/MS recoveries spanned 52% to 122% (RSD < 20%) for 15 analytes. Chromatograms showed clear peak resolution with minimal matrix background. Effective removal of colored pigments in dSPE and robust cartridge cleanup prevented column and injection port fouling, enabling hundreds of GC injections without maintenance.

Benefits and Practical Applications

• Rapid QuEChERS extraction and tailored cleanup deliver high-throughput processing with reduced labor.
• Single mass spectrometer handles both LC and GC analyses with a 30-min interface swap, eliminating downtime and source venting.
• Broad pesticide coverage supports compliance with EU and US MRLs for dietary supplements.
• Cleaner extracts extend column life and lower maintenance costs in routine QC laboratories.

Future Trends and Opportunities

Emerging directions include automated QuEChERS platforms for scale-up, novel sorbent chemistries to target specific matrix interferences, and integration of high-resolution mass spectrometry for non-target screening. Advances in AI-driven method optimization may further reduce development time and enhance multi-residue coverage in complex botanicals.

Conclusion

The optimized workflow employing modified QuEChERS extraction, dSPE for UPLC-MS/MS, and PSA/carbon SPE for APGC-MS/MS achieved reliable quantitation of a wide array of pesticides in ginseng powder. High recoveries, robust matrix cleanup, and seamless instrument versatility demonstrate a practical solution for routine compliance testing of herbal products.

Reference

• Multi-Residue Pesticide Analysis in Tea: Optimized Cleanup After QuEChERS Extraction for UPLC-MS/MS and GC-MS/MS Analysis. Waters Application Note 720004819EN, 2014.