High Resolution and Precise Mass Accuracy: A Perfect Combination for Food and Feed Analysis in Complex Matrices

Significance of the Topic

Accurate screening of pesticides, mycotoxins and veterinary drugs in complex food and feed matrices is critical to ensure safety, compliance with regulations and consumer health protection. Conventional low-resolution mass spectrometry often suffers from unresolved matrix interferences, leading to inaccurate mass measurements, false negatives or positives. Deploying high-resolution, high-accuracy mass analyzers addresses these analytical challenges by enabling confident detection and identification even at trace levels.

Objectives and Study Overview

This study evaluates the analytical advantages of coupling Ultra High-Pressure Liquid Chromatography (U-HPLC) with a new benchtop single-stage Orbitrap mass spectrometer operating at resolutions up to 100,000. The goals were to demonstrate:

• Resolution of co-eluting isobaric pesticides
• Improved elemental composition assignment
• Sensitivity, linearity and selectivity in multi-residue screening of complex matrices

Methodology and Instrumentation

A Thermo Scientific Exactive™ Orbitrap mass spectrometer was interfaced with a Thermo Scientific Accela™ U-HPLC system. A 12-minute gradient using a Hypersil GOLD™ C18 column (50×2 mm, 1.9 μm) with water/acetonitrile eluents was applied to a mixture of 116 pesticides, mycotoxins and plant toxins spiked into animal feed extracts. Mass spectra were acquired at resolution settings of 15,000, 50,000 and 80,000 to benchmark against time-of-flight instruments and to assess the impact of resolving power on mass accuracy, sensitivity and compound coverage. Automatic gain control (AGC) maintained optimal ion populations.

Used Instrumentation

• Thermo Scientific Exactive™ Orbitrap mass spectrometer (single-stage, HCD collision cell)
• Thermo Scientific Accela™ U-HPLC system
• Thermo Scientific Hypersil GOLD™ C18 column (50×2 mm, 1.9 μm)

Main Results and Discussion

The 50,000–80,000 resolution settings fully resolved isobaric pairs such as Thiamethoxam and Parathion (Δm/z ~0.014). At 15,000 resolution, interferences produced mass errors exceeding instrument specifications, complicating elemental formula determination. High resolution also separated isotopic clusters of Azoxystrobin, ensuring accurate A+1 and A+2 isotopic mass measurements. In matrix-spiked samples (100 ppb), 95 out of 116 compounds were detected at R=50,000 within a 3 ppm extraction window, whereas R=15,000 yielded disproportionately fewer identifications due to masked low-abundance pesticides like Sulcotrion. Quantitation down to 2 ppb demonstrated excellent linearity (e.g., Metabenthiazuron response) and reproducibility.

Benefits and Practical Applications

High-resolution Orbitrap analysis offers:

• Enhanced selectivity by resolving co-eluting isobaric species
• Improved mass accuracy for reliable elemental composition assignment
• High sensitivity and dynamic range for trace-level residues in complex matrices
• Compatibility with fast U-HPLC methods at up to 10 Hz scan speeds

These features support regulatory compliance, reduce false positives/negatives and enable retrospective data mining.

Future Trends and Opportunities

Emerging opportunities include integration of All-Ion Fragmentation workflows for structural elucidation, advancement of data-processing algorithms leveraging high-resolution full-scan datasets and expansion into routine multi-class contaminant screens. Further miniaturization and automation of Orbitrap-based platforms will broaden their application in on-site testing and high-throughput quality control.

Conclusion

A benchtop Orbitrap mass spectrometer coupled to U-HPLC combines ultra-high resolution and precise mass accuracy to overcome the limitations of traditional residue analysis. It achieves superior selectivity, sensitivity and quantitation performance in complex food and feed matrices, enabling confident detection and identification of a wide range of contaminants.

Reference

• Kellmann M., Wieghaus A., Muenster H., Taylor L., Ghosh D. High Resolution and Precise Mass Accuracy: A Perfect Combination for Food and Feed Analysis in Complex Matrices. Thermo Fisher Scientific Application Note 30163 (2008).