Routine-grade robustness with the Advanced Electron Ionization source: confirmation of contaminants in food products at trace levels by GC-MS/MS

Importance of the Topic

In modern high-throughput analytical laboratories, minimizing instrument downtime is essential to maintain productivity and control costs. Gas chromatography coupled with triple quadrupole mass spectrometry (GC-MS/MS) demands robust ion sources to handle complex food matrices and trace‐level contaminants without frequent maintenance.

Objectives and Study Overview

This study assesses the routine performance and robustness of the Thermo Scientific TSQ 9000 GC-MS/MS system equipped with the Advanced Electron Ionization (AEI) source and SmartTune feature. Approximately 900 injections of QuEChERS-prepared baby food extracts spiked with 150 pesticides at 10 ppb were analyzed to evaluate peak area repeatability and ion flux stability over extended sequences.

Methodology and Used Instrumentation

Sample Preparation:

• Citrate-buffered QuEChERS extraction of carrot/potato baby food with HyperSep dispersive SPE clean-up.
• Post-spike to 10 μg/kg per pesticide in acetonitrile; dilution kept minimal to avoid matrix effects.

Instrumentation:

• GC: Thermo Scientific TRACE 1310 with Siltek six-baffle programmable temperature vaporization (PTV) inlet.
• Column: TraceGOLD TG-5SilMS (30 m × 0.25 mm, 0.25 μm) with 5 m integrated guard.
• Autosampler: TriPlus RSH for consistent liquid injections (1 μL splitless).
• MS: Thermo Scientific TSQ 9000 triple quadrupole with AEI source at 320 °C in timed selected reaction monitoring (SRM) mode.
• Tuning: Automated SmartTune and optional Advanced Autotune with Argon collision gas (70 psi) and 0.7 Da peak width.

Main Results and Discussion

• Ion flux remained stable across 900 sequential injections, simulating one month of continuous operation, with selected pesticides showing 6.7–8.8 % RSD and consistent qualifier/quantifier ratios.
• Over 90 % of the 150 pesticides exhibited <20 % RSD in ion flux at 10 ppb without any source cleaning or maintenance beyond replacing the PTV liner every 100 injections.
• SmartTune provided a 4–5 minute automated tuning workflow with clear visual status and remediation guidance when source contamination or multiplier exhaustion was detected.

Benefits and Practical Applications

The AEI source combined with SmartTune offers:

• Extended operational intervals and reduced maintenance in high-throughput pesticide monitoring.
• High sensitivity and reproducibility without routine manual source intervention.
• Lower overall cost per sample and improved laboratory efficiency.

Future Trends and Applications

Advances may include deeper integration of intelligent tuning and diagnostics, expansion to diverse high-matrix sample types, next-generation ion source designs for enhanced robustness, and incorporation of real-time analytics for proactive performance management.

Conclusion

The TSQ 9000 GC-MS/MS with AEI source and SmartTune demonstrates outstanding routine-grade robustness and sensitivity for trace pesticide analysis in food products, ensuring reliable high-throughput workflows with minimal downtime.

References

1. QuEChERS Method Database, CVUA Stuttgart.
2. Thermo Fisher Scientific, Sample Preparation Application Note WP-72048.
3. SANTE/11813/2017 Guidance on analytical quality control and method validation for pesticide residues in food and feed.