RAPID AND EFFECTIVE PASS-THROUGH CLEANUP OF HIGH CHLOROPHYLL QUECHERS EXTRACTS PRIOR TO GC-MS/MS AND LC-MS/MS ANALYSIS

Importance of the Topic

Spinach and other leafy vegetable samples processed by QuEChERS often co-extract high levels of chlorophyll and related pigments.
These co-extractives can cause chromatographic interference, contaminate GC and LC instruments and reduce analytical accuracy.
Effective cleanup prior to GC-MS/MS and LC-MS/MS analysis is critical to ensure high throughput, reliable quantitation, and instrument maintenance.

Objectives and Study Overview

This study compares conventional dispersive solid-phase extraction (dSPE) with graphitized carbon black (GCB) at different loadings against a pass-through SPE cleanup using Oasis PRiME HLB cartridges for removal of chlorophyll and planar pesticide recovery in spinach extracts.
Specifically, it focuses on three planar pesticides—cyprodinil, chlorothalonil, thiabendazole—spiked at 50 µg/kg.

Methodology and Used Instrumentation

Sample Preparation and Cleanup

• QuEChERS extraction of 15 g spinach with 1:99 acetic acid/acetonitrile and AOAC salt mix
• dSPE protocols: 150 mg anhydrous MgSO₄, 50 mg C18, 50 mg PSA and either 10 mg or 50 mg GCB per mL extract
• Pass-through cleanup: Oasis PRiME HLB vac-style cartridges (3 cc/150 mg) and “plus” syringe-style formats with 0.8–1.5 mL extract loads; no conditioning required

Instrumentation

• UPLC-PDA: Waters Acquity I-Class FTN, Cortecs UPLC T3 column, 450 nm detection for pigment monitoring
• APGC-MS/MS: Waters Xevo TQ-S, Restek Rxi-5ms GC column, MRM transitions for cyprodinil and chlorothalonil
• UPLC-MS/MS: Waters Acquity UPLC I-Class, BEH C18 column, ESI+ MRM for thiabendazole

Key Results and Discussion

Pigment Removal

• Oasis PRiME HLB cleanup removed >99% chlorophyll and >95% lutein
• dSPE with 10 mg GCB reduced pigments but less effectively than HLB cartridge
• dSPE with 50 mg GCB removed all pigments but caused significant loss of planar pesticides

Pesticide Recovery

• Cyprodinil, chlorothalonil and thiabendazole recoveries were maintained with Oasis PRiME HLB cleanup
• dSPE with 10 mg GCB showed minimal impact on planar pesticide recovery
• dSPE with 50 mg GCB led to substantial losses of planar analytes

Instrument Performance

• Oasis PRiME HLB pass-through provided fast, reproducible flows and streamlined workflow
• No cartridge conditioning spared time and reduced solvent consumption

Benefits and Practical Applications

• Improved sample throughput via rapid pass-through SPE cleanup
• Enhanced instrument uptime by minimizing pigment-induced contamination
• Robust pesticide quantitation by preserving planar analytes
• Modular cartridge formats adaptable to vacuum manifolds or syringe processing

Future Trends and Potential Applications

Integration of simplified SPE sorbents may extend to other high-pigment matrices such as leafy herbs or algae.
Advances in sorbent chemistry could further refine selectivity for pigments versus analytes.
Automation of pass-through workflows in 96-well formats could boost laboratory throughput in food safety and environmental testing.

Conclusion

Pass-through SPE with Oasis PRiME HLB cartridges outperforms conventional dSPE for chlorophyll and lutein removal in QuEChERS spinach extracts while preserving recoveries of planar pesticides.
dSPE requires careful balance of GCB to avoid analyte losses.
Adopting streamlined HLB cleanup enhances analytical efficiency, accuracy and instrument robustness for GC-MS/MS and LC-MS/MS applications.

References

No additional literature references were provided.