A Fast and Robust GC/MS/MS Analysis of 203 Pesticides in 10 Minutes in Spinach

Significance of the Topic

Rapid screening for pesticide residues in high-chlorophyll matrices such as spinach is critical for food safety and regulatory compliance. Accelerating GC/MS/MS methods while preserving resolution and robustness addresses sample throughput bottlenecks in analytical laboratories.

Objectives and Study Overview

This work describes two fast, 10-minute GC/MS/MS protocols for simultaneous quantitation of 203 pesticides in spinach. Both methods employ midcolumn backflush configurations on an Agilent 8890 GC combined with either a 7000E or 7010C triple quadrupole mass spectrometer. The first method uses a conventional 15 m × 0.25 mm × 0.25 µm column, and the second uses a mini-bore 10 m × 0.18 mm × 0.18 µm column scaled via GC method translation.

Methodology and Instrumentation

• Instrumentation: Agilent 8890 GC, 7693A autosampler with temperature-programmed multimode inlet, Ultimate Union midcolumn backflush, and pneumatic switching device.
• Mass Spectrometry: Agilent 7000E and 7010C triple quadrupoles in dynamic MRM mode, enabling up to 614 total transitions with efficient dwell allocation.
• Columns: 15 m × 0.25 mm × 0.25 µm and 10 m × 0.18 mm × 0.18 µm HP-5ms phases with midcolumn backflush to minimize matrix loading.
• Sample Preparation: QuEChERS extraction followed by Agilent Captiva EMR–High Chlorophyll pass-through cleanup.
• Retention Time Locking and Method Translation: Ensured consistent elution order and accurate retention times when transferring methods between column formats.

Main Results and Discussion

• All 203 pesticides were resolved and quantified within 10 minutes with three MRM transitions per analyte.
• Excellent sensitivity achieved: quantitation down to 0.1 ppb for challenging compounds (e.g., fludioxonil, deltamethrin).
• Linear calibration (R² > 0.99) over 0.1–1,000 ppb or 0.5–1,000 ppb for the majority of analytes, covering regulatory MRLs.
• Robust performance demonstrated by 700 continuous injections of 20 ppb spinach extracts (over 175 hours) with only septum and inlet liner replacements at 100-injection intervals.

Benefits and Practical Applications

• Halves cycle time compared to conventional 20-minute methods, boosting sample throughput.
• Midcolumn backflush reduces column trimming and source cleaning frequency, extending maintenance intervals.
• Dynamic MRM scheduling accommodates hundreds of concurrent transitions with minimal dwell compromise.
• GC method translation simplifies method setup and transfer across instruments and column formats.

Future Trends and Potential Applications

• Integration of advanced ion sources and vacuum technologies for enhanced sensitivity and lower detection limits.
• Expansion of rapid multiresidue workflows to diverse food and environmental matrices.
• Automation of retention time locking, method translation, and real-time QC monitoring in data acquisition software.
• Application of machine learning for automated anomaly detection and calibration drift correction.

Conclusion

The described midcolumn backflush GC/MS/MS methods deliver a robust, 10-minute assay for over 200 pesticides in spinach without compromising resolution, sensitivity, or maintenance schedules. These workflows significantly improve laboratory efficiency and support regulatory compliance in food testing.

Instrumentation Used

• Agilent 8890 Gas Chromatograph
• Agilent 7000E and 7010C Triple Quadrupole Mass Spectrometers
• Agilent 7693A Autosampler and Temperature-Programmed Multimode Inlet
• Agilent Captiva EMR–High Chlorophyll Cleanup Cartridges

References

1. Agilent MassHunter pesticide and environmental pollutants MRM database (P&EP 4.0).
2. Agilent GC custom column and method translation guides.
3. 40 CFR §180.435 – Deltamethrin tolerances.
4. US EPA fludioxonil tolerance information.
5. IPCS InChem pesticide monographs.
6. Andrianova, A., Zhao, L. Agilent application note 5994-4965EN.