A NOVEL SORBENT FOR PASS-THROUGH SPE CLEANUP: A SIMPLE, QUICK, AND EFFECTIVE ALTERNATIVE FOR REMOVAL OF LIPIDS AND CHLOROPHYLL FROM QUECHERS EXTRACTS

Importance of the Topic

The removal of co-extracted lipids, phospholipids, and pigments from QuEChERS extracts is critical to ensure reliable pesticide analysis and protect LC/GC-MS instrumentation. High-fat matrices such as avocado and high-chlorophyll matrices like spinach pose significant challenges due to chromatographic interferences, ion suppression, and instrument contamination.

Objectives and Study Overview

This study evaluates a novel pass-through SPE cleanup using Oasis PRiME HLB sorbent as an alternative to traditional multi-step dispersive SPE (dSPE). The goal is to achieve rapid, simple, and effective removal of fats, phospholipids, chlorophyll, and carotenoids from QuEChERS extracts of avocado and spinach while maintaining high pesticide recoveries. Performance is compared across three cleanup modes: Oasis PRiME HLB, dSPE with 10 mg GCB, and dSPE with 50 mg GCB per mL of extract.

Methodology and Instrumentation

• Sample Preparation: QuEChERS extraction modified for avocado (5 g sample) and spinach (15 g sample) with 1% acetic acid in acetonitrile, followed by partitioning salts.
• Pass-through SPE Cleanup: 0.8 mL of supernatant discarded, 1.5 mL collected through a 3 cc Oasis PRiME HLB cartridge under ~2 psi vacuum, then centrifuged.
• dSPE Cleanup: 1 mL extract treated with C18, PSA, and either 10 mg or 50 mg GCB, hand shaken and centrifuged.
• Analytical Systems:
• UPLC-MS/MS: Waters ACQUITY UPLC I-Class with BEH C18 (100 × 2.1 mm, 1.7 µm), Xevo TQ-S micro, ESI+ MRM.
• UPLC-PDA: Acquity I-Class FTN with Cortecs UPLC T3 (100 × 2.1 mm), monitored at 450 nm.
• APGC-MS/MS: Agilent 7890 GC with Restek Rxi-5ms column, Waters Xevo TQ-S micro in API+ MRM.
• GC-MS Fat Analysis: Methylation of fatty acids and TIC detection.

Main Results and Discussion

• Oasis PRiME HLB removed >95% of phospholipids and fats from avocado extracts.
• Chlorophyll and carotenoids removal exceeded 99% and 95%, respectively, from both avocado and spinach QuEChERS extracts.
• dSPE with 50 mg GCB eliminated pigments but caused significant losses (>20%) of planar pesticides (cyprodinil, chlorothalonil, thiabendazole).
• Pass-through cleanup preserved recoveries of planar and non-planar pesticides, showing minimal analyte loss.
• No conditioning of the Oasis PRiME HLB cartridge was necessary, and various cartridge formats (Plus, Vac, Light) performed equivalently.

Benefits and Practical Applications

• Streamlined, single-step cleanup reduces hands-on time and simplifies workflow.
• Enhanced instrument uptime due to reduced matrix fouling.
• Improved data quality with higher pesticide recoveries and lower background interference.
• Compatibility with a wide range of pesticide chemistries, including planar analytes.

Future Trends and Potential Applications

• Adaptation of pass-through SPE cleanup to additional high-matrix commodities such as berries, nuts, and leafy greens.
• Integration with automated SPE platforms for high-throughput laboratories.
• Combination with novel sorbents targeting other interferences (e.g., pigments, amino acids) for multimodal cleanup.
• Extension to environmental and forensic sample preparation workflows.

Conclusion

The Oasis PRiME HLB pass-through SPE method offers a rapid, robust, and effective alternative to traditional dSPE for QuEChERS extracts of high-fat and high-pigment matrices. It achieves superior removal of lipids, phospholipids, chlorophyll, and carotenoids while preserving pesticide recoveries and protecting analytical instrumentation.

Reference

• Young MS, Tran K, Shia JC. A novel sorbent for pass-through SPE cleanup: removal of lipids and chlorophyll from QuEChERS extracts. Waters Corporation, Milford, MA.