Oasis PRiME HLB Cartridges for Rapid and Effective Removalof Chlorophyll from QuEChERS Spinach Extracts

Importance of Chlorophyll Removal in QuEChERS Extracts

Chlorophyll and other pigments extracted during QuEChERS sample preparation can contaminate chromatographic systems, cause instrument fouling, reduce column lifetime, and impair analytical accuracy. Effective pigment removal is therefore critical for reliable pesticide residue analysis in high-chlorophyll matrices such as spinach.

Study Objectives and Overview

This study evaluates a pass-through cleanup approach using Oasis PRiME HLB Cartridges against traditional dispersive SPE (dSPE) with graphitized carbon black (GCB). Key objectives include:

• Assessing chlorophyll and carotene removal efficiency from spinach QuEChERS extracts
• Comparing recoveries of planar pesticides (cyprodinil, chlorothalonil, thiabendazole)

Methodology and Instrumentation

Spinach samples (15 g) were spiked at 50 µg/kg with target pesticides and extracted with acetonitrile/acetic acid. Cleanup protocols:

• dSPE: 150 mg Na₂SO₄, 50 mg C18 silica, 50 mg PSA, and either 10 mg or 50 mg GCB per mL extract
• Oasis PRiME HLB Cartridges: Vac format (3 mL, 150 mg) and Plus formats (Short and Light) with no conditioning required

Instrumentation:

• UPLC-PDA (ACQUITY I-Class FTN, Cortecs UPLC T3 column, 450 nm) for pigment monitoring
• APGC-MS/MS (Xevo TQ-S, Restek Rxi-5 ms GC column) for cyprodinil and chlorothalonil quantification
• UPLC-MS/MS (Xevo TQ-S micro, BEH C18 column, ESI+) for thiabendazole analysis

Main Results and Discussion

Oasis PRiME HLB pass-through cleanup removed over 99% of chlorophyll and more than 95% of lutein, outperforming dSPE with 10 mg GCB. Although dSPE with 50 mg GCB achieved complete pigment removal, it caused significant losses of planar pesticides. In contrast, Oasis PRiME HLB maintained high recoveries of cyprodinil, chlorothalonil, and thiabendazole with negligible loss.

Practical Benefits and Applications

• Simplified workflow: no cartridge conditioning or additional solvents
• Flexible formats: compatible with syringes or vacuum/positive pressure manifolds
• High analyte recovery: minimal loss of planar pesticides preserves sensitivity
• High throughput: suitable for routine pesticide residue testing in leafy greens

Future Trends and Opportunities

Pass-through SPE media like Oasis PRiME HLB are poised to streamline multi-residue pesticide workflows by reducing sorbent use, solvent consumption, and sample preparation time. Future developments may include automation of cleanup steps, integration with novel detection platforms, and validation across a broader range of high-pigment commodities.

Conclusion

Oasis PRiME HLB Cartridges deliver a rapid, robust, and effective cleanup solution for spinach QuEChERS extracts, achieving superior pigment removal and preserving planar pesticide recoveries compared to conventional GCB-based dSPE.

Reference

• Oasis PRiME HLB Cartridge for Rapid and Effective Cleanup of Avocado, A High Fat Matrix, Prior to APGC-MS/MS Analysis, Waters Application Note 720005816EN, 2016.