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

Significance of the topic

High levels of chlorophyll and other pigments co-extracted during QuEChERS sample preparation of leafy vegetables can cause chromatographic interference, contaminate GC and LC systems, and degrade mass spectrometer performance. Implementing an effective, rapid cleanup step is essential to maintain analytical accuracy and instrument uptime in food safety testing laboratories.

Objectives and overview of the study

The study compared traditional dispersive SPE (dSPE) using graphitized carbon black with a pass-through cleanup approach employing Oasis PRiME HLB cartridges. Key aims were to assess pigment removal efficiency and to evaluate recovery of three planar pesticides—cyprodinil, chlorothalonil, and thiabendazole—spiked into spinach at 50 µg/kg.

Methodology and sample preparation

• QuEChERS extraction: 15 g homogenized spinach with 15 mL 1:99 acetic acid/acetonitrile, QuEChERS salt pouch, manual shaking and centrifugation.
• dSPE cleanup: 1 mL extract treated with C18, PSA, sodium sulfate and either 10 mg or 50 mg GCB per mL, followed by centrifugation.
• Pass-through cleanup: 0.8 mL extract discarded and 1.5 mL collected through Oasis PRiME HLB cartridges (vac or plus formats) without conditioning steps.
• Analysis:
– Pigment monitoring by UPLC-PDA at 450 nm
– GC-APGC-MS/MS for cyprodinil and chlorothalonil
– UPLC-MS/MS for thiabendazole

Instrumentation

• Waters ACQUITY UPLC I-Class FTN with PDA detector and Cortecs UPLC T3 (2.1 × 100 mm) column
• Waters ACQUITY UPLC I-Class with BEH C18 (1.7 µm, 100 × 2.1 mm) column
• Agilent 7890 GC with Restek Rxi-5ms column and Waters Xevo TQ-S for APGC-MS/MS
• Waters Xevo TQ-S micro for UPLC-MS/MS
• MassLynx v4.1 data system

Key results and discussion

• Oasis PRiME HLB cartridges removed over 99 % of chlorophyll and over 95 % of lutein in under two minutes.
• dSPE with 10 mg GCB partially removed pigments but left residual chlorophyll peaks.
• dSPE with 50 mg GCB eliminated pigments but caused significant losses of planar pesticides.
• Pass-through cleanup achieved high pigment removal with minimal loss (<5 %) of cyprodinil, chlorothalonil, and thiabendazole.

Benefits and practical applications

• Streamlined protocols with no conditioning or equilibration reduce preparation time and risk of sorbent plugging.
• High-throughput compatibility for food safety laboratories requiring rapid turnaround.
• Improved data quality by minimizing matrix effects and instrument maintenance frequency.

Future trends and potential applications

• Automation of pass-through SPE in online and robotic systems to further increase throughput.
• Extension of PRiME HLB cleanup strategies to other challenging matrices such as high-fat or high-pigment foods.
• Development of sorbent chemistries tailored for specific classes of emerging contaminants.

Conclusion

Pass-through cleanup with Oasis PRiME HLB cartridges offers a rapid, effective solution for removing chlorophyll and preserving pesticide recoveries in QuEChERS spinach extracts, outperforming traditional dSPE approaches and enhancing laboratory productivity.

Reference

• Young MS, Tran K, Shia JC. Rapid and Effective Pass-Through Cleanup of High Chlorophyll QuEChERS Extracts Prior to GC-MS/MS and LC-MS/MS Analysis. Waters Corporation; 2017.