Oasis PRiME HLB Cartridge for Clean-up of QuEChERS Extracts of Soybean Pods Prior to UPLC-MS/MS Determination of Free Acidic Herbicides

Significance of the Topic

Reliable determination of free acidic herbicides in agricultural products is essential for food safety and regulatory compliance. Edamame (soybean pods) presents analytical challenges due to its lipid, phospholipid, and pigment content, which can interfere with UPLC-MS/MS analysis and damage instrumentation. A streamlined sample preparation and cleanup approach can enhance throughput, reduce costs, and improve data quality for multi-residue pesticide screening.

Objectives and Study Overview

The study evaluated a QuEChERS extraction coupled with pass-through cleanup using the Oasis PRiME HLB Cartridge to quantify free acidic herbicides in edamame by UPLC-MS/MS. Key goals included achieving effective removal of fats, phospholipids, and pigments, maintaining high analyte recovery, and enabling simultaneous analysis of acidic, neutral, and basic pesticides from a single extract.

Methodology

Sample Preparation and Cleanup

• Homogenize 5 g edamame, fortify if needed, equilibrate 30 min
• Add 10 mL water and 10 mL acetonitrile, vortex, then add CEN QuEChERS salts
• Shake 10 min, centrifuge at 4000 rpm for 5 min, collect supernatant
• Pass 0.7 mL supernatant through Oasis PRiME HLB Cartridge under 1–2 psi (discard flow-through)
• Collect 1.2 mL pass-through, dilute 0.20 mL with 0.40 mL water for analysis

Used Instrumentation

Liquid Chromatography

• System: ACQUITY UPLC I-Class with HSS T3 column (2.1 × 100 mm, 1.8 µm)
• Mobile phase A: 0.02% formic acid in water; B: acetonitrile:methanol (50:50)
• Gradient: 95% A to 5% A over 5 min; flow 0.4 mL/min; column 25 °C; injection 10 µL

Mass Spectrometry

• System: Xevo TQ-XS Tandem MS, ESI+ and ESI−
• Source: 120 °C; desolvation 300 °C; cone gas 30 L/hr; desolvation gas 1000 L/hr
• Monitored MRM transitions for 30+ acidic herbicides; data acquired with MassLynx v4.2

Main Results and Discussion

Recovery studies at 1, 10, and 100 ng/g spiking levels showed overall method recoveries above 70% for most acidic herbicides, with higher variability for polar compounds like picloram. Pass-through cleanup removed over 95% of phospholipids and pigments, preventing column and source contamination. Comparison of total method versus SPE-only recoveries confirmed that losses for certain analytes stem from the initial extraction rather than the HLB cleanup.

Benefits and Practical Applications

• One-step cleanup for acidic, neutral, and basic pesticides from a single QuEChERS extract
• Significant removal of fats and phospholipids reduces instrument maintenance and extends column life
• High throughput and time savings for routine multi-residue pesticide screening
• Robust recoveries suitable for regulatory monitoring and QA/QC laboratories

Future Trends and Opportunities

Further developments may include optimized methods for bound herbicides via hydrolysis, expansion to additional complex matrices, automation of pass-through cleanup in 96-well formats, integration with high-resolution MS, and exploration of alternative sorbent chemistries or greener solvents to enhance sustainability.

Conclusion

The combination of QuEChERS extraction and Oasis PRiME HLB pass-through cleanup provides an efficient, reliable workflow for UPLC-MS/MS analysis of free acidic herbicides in edamame. This approach simplifies sample preparation, ensures high analyte recovery, and minimizes matrix interferences in a single procedure.

References

1. Carneiro RP, et al. Food Control. 2013;33:413–423.
2. Lehotay SA, et al. J AOAC Int. 2005;88(2):595–614.