Effcient extraction of residual pesticides in agricultural products and soils for GC/MS and LC/MS analysis using supercritical fuid extraction

Significance of the Topic

Efficient and rapid extraction of residual pesticides from agricultural products and soils is crucial for ensuring food safety, environmental protection and compliance with regulatory limits. Conventional solvent extraction methods often require large volumes of organic solvents and lengthy processing times. Supercritical fluid extraction (SFE) using carbon dioxide offers high diffusivity, reduced solvent consumption and faster processing, meeting the growing demand for greener and more efficient analytical workflows.

Objectives and Study Overview

This study aimed to develop and evaluate an automated SFE system for the pretreatment of residual pesticides in agricultural matrices (brown rice) and soils. The system is coupled with GC-MS and LC-MS to determine extraction efficiency, repeatability and recovery for a broad range of pesticide compounds under optimized conditions.

Methodology and Instrumentation

The sample preparation involved mixing 1 g of homogenized sample with 1 g of dehydrating absorbent and enclosing the mixture in an extraction vessel. SFE was performed using a Nexera UC SFE pretreatment system in static and dynamic modes with supercritical CO2 and methanol as modifier. Key parameters included:

• Flow rate: 5 mL/min
• Extraction temperature: 40 °C
• Back pressure regulator: 15 MPa
• Extraction time: 8 min for agricultural products, 4 min for soils
• Trap column: Shim-pack VP-ODS (50 mm × 4.6 mm, 5 μm)

Eluate was concentrated to 2 mL with acetone/hexane and analyzed by:

• GC-MS (GCMS-TQ8040): Rxi-5Sil MS column, splitless injection, MRM mode
• LC-MS (Nexera X2 with LCMS-8060): Shim-pack UC-RP column, gradient of ammonium formate in water and methanol, ESI in positive/negative MRM mode

Main Results and Discussion

Off-line SFE/GC-MS analysis of brown rice spiked at 100 ng/g demonstrated reliable quantification of 301 out of 354 target pesticides, with peak area RSD below 10% and recoveries of 70–120%.
Soil samples spiked at 200 ng/g were analyzed by off-line SFE/LC-MS. Eight representative pesticides showed repeatability (RSD <5%) and recoveries within 70–120%.

Benefits and Practical Applications

The developed SFE method reduces sample preparation time to approximately 30 minutes per sample, supports automated serial extraction of up to 48 samples and drastically lowers organic solvent usage. These advantages translate into increased laboratory throughput, cost savings and minimized environmental impact, making the approach well suited for QA/QC in food safety, environmental monitoring and research laboratories.

Future Trends and Potential Applications

Future developments may include integration with high-resolution mass spectrometry for expanded analyte coverage, real-time online coupling of SFE with detection systems, and extension to complex matrices such as animal tissues and processed foods. Advances in SFE hardware and green chemistry will further enhance method sustainability and analytical performance.

Conclusion

The automated SFE system demonstrated fast, efficient and reproducible extraction of a wide range of pesticide residues in agricultural products and soils. Coupled with GC-MS and LC-MS, the method offers robust quantification with high throughput and reduced solvent consumption, aligning with current demands for eco-friendly and cost-effective analytical solutions.

Used Instrumentation

• Nexera UC SFE Pretreatment System (Shimadzu)
• GCMS-TQ8040 (Shimadzu)
• Nexera X2 LC system with LCMS-8060 (Shimadzu)