Improvements in Robustness of Signal Response in Multiresidue Pesticide Analysis with Xevo TQ Absolute XR Mass Spectrometer

Significance of the Topic

The ability to maintain stable signal response and ion ratios in fast multiresidue pesticide analysis enhances laboratory throughput, reduces downtime, and ensures data reliability. Challenging matrices such as crude fish feed extracts introduce high levels of matrix ions that can contaminate mass spectrometer optics and quadrupoles, leading to unplanned maintenance and compromised quantitative performance. Improvements in ion transmission and contaminant removal directly impact routine food testing workflows and regulatory compliance.

Study Objectives and Overview

This study evaluated the robustness of the StepWave XR ion guide integrated into the Xevo TQ Absolute XR Tandem Quadrupole Mass Spectrometer for multiresidue analysis of over 200 pesticides in a crude fish feed extract. A rapid six-minute LC-MS/MS method was developed to challenge the system with high matrix loading and frequent polarity switching. More than 14,000 injections were performed without clean-up or waste diversion to assess signal stability, ion ratio consistency, and quadrupole contamination over extended operation.

Methodology

Sample Preparation was based on a QuEChERS protocol. Two grams of fish feed were rehydrated and extracted with 10 mL acetonitrile using a DisQuE QuEChERS CEN pouch. After centrifugation, the extract was spiked with 204 pesticides and diluted 1 in 10 to achieve a final concentration of 0.01 micrograms per milliliter. Eighty vials were prepared, and 1 microliter was injected for each analysis. No waste diversion was employed to maximize matrix load.

Instrumental Setup

• LC System: ACQUITY Premier with Binary Solvent Manager and Flow-Through Needle; column ACQUITY UPLC HSS T3 2.1 x 30 mm, 1.8 micrometer; column temperature 40 °C; sample temperature 10 °C; flow 0.5 mL per minute; mobile phases of 5 mM ammonium acetate with 0.1 percent formic acid in water (A) and in 1/1 acetonitrile/methanol (B).
• MS System: Xevo TQ Absolute XR; ESI positive and negative modes; capillary voltage 2 kV; source temperature 150 °C; desolvation temperature 550 °C; desolvation gas flow 1000 L per hour; cone flow 150 L per hour; a scheduled multiple reaction monitoring method covering 204 pesticides with two transitions each.

Key Results and Discussion

A dedicated quadrupole charging test using fluazinam demonstrated that the Xevo TQ Absolute XR improved operational lifespan by more than sixfold compared to its predecessor before significant charging occurred. Ion ratio plots for representative negative ion compounds such as fluazinam, fipronil desulfinyl, and hexaflumuron remained within a 30 percent tolerance window for over 14,000 injections. A cross section of analytes showed that 82 percent of compounds exhibited ion ratio RSD values below 10 percent over the entire test series. The StepWave XR guide effectively removed contaminant clusters, preventing fouling of ion optics and quadrupoles throughout a ten-week period of continuous analysis.

Benefits and Practical Applications

• Extended instrument uptime with zero unscheduled maintenance during 14,000 injections.
• Consistent ion ratio performance enhances confidence in quantitative data and confirmation criteria.
• Rapid six-minute runtime supports high sample throughput in routine food safety and environmental laboratories.
• Integration with accelerated data validation workflows simplifies batch review and reporting.

Future Trends and Applications

Further enhancements in ion guide design and contamination control will enable even faster acquisition rates and support analysis of more complex matrices. Integration with automated sample preparation and artificial intelligence–driven maintenance alerts could reduce manual intervention. Expanding this robust approach to other application areas such as environmental testing, clinical screening, and metabolomics will broaden its impact. Continued development of digital data management platforms will streamline regulatory reporting and laboratory informatics.

Conclusion

The StepWave XR ion guide within the Xevo TQ Absolute XR Mass Spectrometer delivers exceptional robustness for high-throughput multiresidue pesticide analysis in challenging matrices. Its ability to maintain stable ion ratios and prevent quadrupole charging over thousands of injections offers laboratories reliable performance, reduced downtime, and consistent quantitative results.

References

1. Feed Tables webpage, available at https://www.feedtables.com/content/fish-meal-protein-65 (last accessed May 2025)