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

Importance of the Topic

Reliable monitoring of pesticide residues in agricultural products and soils is essential for food safety, regulatory compliance and environmental protection. Traditional solvent-based extraction methods often require extensive time, labor and large volumes of organic solvents, posing cost and sustainability challenges. Supercritical fluid extraction (SFE) using CO₂ offers a fast, efficient and eco-friendly alternative, combining high diffusivity with reduced solvent consumption.

Study Objectives and Overview

This work aimed to develop and evaluate an automated SFE pretreatment system for simultaneous extraction of a broad range of pesticides from foodstuffs and soil samples. Specific goals included:

• Optimizing a simple sample-preparation workflow
• Validating extraction efficiency for over 350 GC-amenable pesticides in brown rice
• Assessing recovery and precision for eight LC-amenable pesticides in soil

Methodology and Instrumentation

Sample Preparation:

• Homogenize 1 g of agricultural product or soil with 1 g of drying agent
• Pack mixture into an extraction vessel

SFE Conditions:

• System: Nexera UC SFE with CO₂/methanol co-solvent
• Flow: 5 mL/min, 40 °C, 15 MPa back-pressure
• Extraction times: 8 min (foods), 4 min (soils)
• Trap: VP-ODS column; elution to 2 mL acetone/hexane (1:1)

GC-MS (GCMS-TQ8040):

• Column: Rxi-5Sil MS (30 m×0.25 mm, 0.25 µm)
• Temperature program: 50 °C→300 °C ramp
• MRM detection, splitless injection

LC-MS (LCMS-8060):

• Column: UC-RP 3 µm (150 mm×2.1 mm)
• Mobile phases: 10 mM ammonium formate (water/methanol)
• Gradient: 0→100% B over 14 min
• ESI MRM in positive/negative modes

Key Results and Discussion

Food Matrix (Brown Rice):

• 354 pesticides screened; 301 compounds achieved repeatability (RSD <10%) and recovery (70–120%) at 100 ng/g spike levels
• Log P range from highly polar to nonpolar pesticides showed consistent extraction performance

Soil Matrix:

• Eight test pesticides spiked at 200 ng/g
• All analytes demonstrated RSD <5% and recoveries between 70% and 88%

These results confirm that SFE can match or exceed traditional extraction in speed and reliability, while significantly reducing organic solvent use.

Benefits and Practical Applications

• Rapid throughput: ≤30 min per sample including extraction and elution
• Automated serial extraction of up to 48 samples enhances lab efficiency
• Lower solvent consumption reduces costs and environmental impact
• Adaptable to both GC- and LC-detectable pesticide classes

Future Trends and Opportunities

Integration of SFE with on-line coupling to chromatographic systems could further reduce manual steps and sample handling. Advances in trap column chemistries may broaden analyte scope. Expansion into multi-residue screening for mycotoxins, veterinary drugs and emerging contaminants can leverage this platform. Finally, miniaturization and field-deployable SFE units hold promise for on-site testing.

Conclusion

The developed SFE pretreatment system delivers a streamlined, high-throughput methodology for extracting diverse pesticide residues from foods and soils. It offers robust analytical performance, significant solvent savings and potential for broader environmental and food safety applications.

Used Instrumentation

• Shimadzu Nexera UC SFE pretreatment system
• Shimadzu GCMS-TQ8040 triple-quadrupole GC-MS
• Shimadzu Nexera X2 LC coupled to LCMS-8060 triple-quadrupole MS