Developing New Methods for Pesticides in Dietary Supplements

Importance of the topic

Dietary supplements derived from botanical sources pose significant analytical challenges due to complex matrices and the necessity to comply with cGMP regulations requiring routine pesticide screening. Developing efficient, reproducible, and cost effective methods is critical to ensure consumer safety and regulatory compliance while minimizing environmental impact.

Objectives and Study Overview

This study aimed to establish a streamlined workflow for the analysis of 46 pesticides in dry botanical supplements, using dandelion root powder as a model matrix. The goal was to compare the traditional FDA PAM 303 method with a QuEChERS extraction followed by cartridge solid phase extraction cleanup and GC‐TOFMS detection, in order to improve recovery, reduce solvent and sorbent use, and limit analyst variability.

Methodology and Instrumentation

The proposed method begins by wetting 1 g of powdered supplement with 9 mL of water, fortifying with a pesticide mix and internal standards, and allowing a 2 hour equilibration. Extraction follows the EN 15662 QuEChERS protocol using 10 mL acetonitrile and preweighed buffering salts. Cleanup was performed on Resprep Combo SPE cartridges packed with CarboPrep 90 and PSA sorbents. Elution with acetonitrile:toluene, evaporation under nitrogen, and solvent exchange to toluene yielded a final extract for analysis by GC‐TOFMS. Instrumentation included a LECO Pegasus GCxGC‐TOFMS fitted with an Rxi‐5Sil MS column operating in full mass range electron ionization mode at 5 spectra/sec acquisition rate.

Main Results and Discussion

Cartridge SPE provided superior removal of sugars, fatty acids, and pigments compared to dispersive SPE, reducing matrix interferences and protecting the GC inlet and column. TOFMS deconvolution algorithms enabled reliable detection of coeluting analytes and offered full scan sensitivity for potential non‐target screening. Recoveries for the majority of pesticides ranged from 70 to 110 %, including relatively polar compounds, demonstrating the effectiveness of acetonitrile extraction and sorbent cleanup. Early eluting volatile analytes showed slightly lower recoveries due to evaporative losses.

Benefits and Practical Applications

• 20× reduction in solvent use and 5× reduction in sorbent compared to PAM 303
  
• Faster sample throughput with minimal manual preparation using prepackaged salts and SPE cartridges
  
• Enhanced reproducibility and lower analyst‐to‐analyst variation
  
• Improved cleanup of complex botanical matrices for routine QA/QC labs
  
• Potential for non‐target pesticide screening using full scan TOFMS data

Future Trends and Possibilities

Expansion of QuEChERS‐based protocols to other supplement matrices, spices, and essential oils is anticipated. Integration of GCxGC for enhanced separation and adoption of high‐resolution mass spectrometry may further improve selectivity and the capability to detect emerging or unknown contaminants. Automation of extraction and cleanup steps could drive higher sample throughput in regulated environments.

Conclusion

The combination of QuEChERS extraction, cartridge SPE cleanup, and GC‐TOFMS detection provides a robust, economical, and environmentally friendly method for multi‐residue pesticide analysis in dietary supplements. This approach meets cGMP requirements, offers high recoveries across diverse chemistries, and ensures reliable data for regulatory oversight.

Reference

• [1] US Food and Drug Administration. Current Good Manufacturing Practice in Manufacturing, Packaging, Labeling, or Holding Operations for Dietary Supplements. 2007.
• [2] Anastassiades M, Lehotay SJ, Stajnbaher D, Schenck FJ. J AOAC Int. 2003;86:412.
• [3] Wong JW, Wirtz MS, Hennessy MK, Schenck FJ, Krynitsky AJ, Capar SG. Acta Hort (ISHS). 2006;720:113.
• [4] EN 15662: 2008. Foods of Plant Origin—Determination of Pesticide Residues Using GC‐MS and/or LC‐MS/MS Following Acetonitrile Extraction and Dispersive SPE Cleanup.
• [5] Okihashi M, Kitagawa Y, Akutsu K, Obana H, Tanaka Y. J Pestic Sci. 2005;30:368.