Clean-up of Organochlorine and Organophosphorus Pesticides from Vegetable Extracts Using ISOLUTE® SAX/PSA Columns

Importance of the Topic

The removal of organochlorine and organophosphorus pesticides from vegetable extracts is crucial to ensure accurate residue analysis and protect food safety. Effective clean-up reduces matrix interferences, enhances sensitivity in GC/GC-MS, and streamlines routine testing in analytical laboratories.

Objectives and Overview of the Application Note

This application note presents a streamlined procedure for the clean-up of non-polar pesticide extracts from various vegetable matrices. It focuses on using ISOLUTE SAX/PSA polar/anion exchange SPE columns to selectively retain polar interferences while allowing target pesticides to be eluted and analyzed efficiently.

Methodology and Used Instrumentation

The workflow combines solvent extraction, liquid–liquid partitioning, and SPE clean-up:

• Pre-treatment: Homogenize 20 g of vegetable sample with 100 mL acetonitrile, filter, concentrate to 25 mL, add 50 mL NaCl-saturated water, and extract twice with 50 mL dichloromethane. Dry over anhydrous sodium sulfate, evaporate, and reconstitute in acetone:hexane (5:95, 2 mL).
• SPE Clean-up: Condition ISOLUTE SAX/PSA (1 g/6 mL) with 10 mL acetone:hexane (5:95). Apply sample at 1–2 mL/min, elute pesticides with 10 mL the same solvent, evaporate to dryness, and reconstitute in 4 mL acetone:hexane (5:95).
• Optional Fat Removal: For fatty matrices, add 75 mL hexane (acetonitrile-saturated) to the filtrate after pre-treatment, shake, and discard the hexane layer prior to SPE.

Used Instrumentation:

• ISOLUTE SAX/PSA SPE columns (1 g/6 mL and 2 g/6 mL formats)
• Gas Chromatography (GC) and GC-Mass Spectrometry (GC-MS) for analysis

Main Results and Discussion

The ISOLUTE SAX/PSA sorbent effectively binds polar pigments and fatty co-extractives, resulting in cleaner extracts of non-polar pesticides with minimal analyte loss. The optimized solvent system (acetone:hexane) ensures efficient elution of target compounds. Incorporating a hexane wash in fatty samples further improves extract clarity and instrument performance.

Benefits and Practical Applications

• Broad applicability to organochlorine and organophosphorus pesticides across diverse vegetable matrices
• Enhanced analytical sensitivity and reproducibility by removing co-extractives
• Scalable procedure compatible with routine laboratory workflows
• Reduced maintenance and downtime for GC/GC-MS instrumentation

Future Trends and Possibilities of Use

• Automation of SPE clean-up for high-throughput pesticide monitoring
• Expansion of sorbent chemistries to target emerging contaminants
• Integration with liquid chromatography–tandem mass spectrometry (LC-MS/MS) for multi-residue analysis
• Application in environmental and food safety laboratories for rapid screening

Conclusion

The described SPE-based clean-up protocol using ISOLUTE SAX/PSA columns offers a robust, efficient, and versatile solution for preparing non-polar pesticide extracts from vegetable samples. Its simplicity and high selectivity support accurate and reliable GC/GC-MS analysis in routine and regulatory settings.

Reference

Biotage Application Note IST1027A.V.1 (2020)