Rapid Quantitation of Veterinary Dyes in Salmon Extracts Using PaperSpray Coupled with a TSQ Altis MS

Significance of the topic

The vigilance for veterinary dye residues in aquaculture products is critical for food safety and regulatory compliance. These dyes, often used as antibacterial agents in fish farming, can pose health risks if present above permissible limits. Rapid, sensitive, and high-throughput analytical methods are therefore essential to ensure that fish products meet global residue guidelines and to facilitate timely decision-making in quality control laboratories.

Objectives and Study Overview

This study aimed to establish a fast screening and quantitation workflow for twelve common veterinary dyes in salmon extracts. By integrating a paper-spray ionization source with a triple quadrupole mass spectrometer, the investigators sought to achieve low limits of quantification, minimal sample preparation, and robust performance across both fresh and frozen salmon matrices.

Methodology

A modified Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) protocol was applied to extract dyes from salmon tissue. Calibration standards (0.2–100 ppb) were prepared by spiking salmon extracts with twelve target dyes and three internal standards. Aliquots of processed extract were deposited onto specialized paper plates, dried, and analyzed directly using paper-spray ionization coupled to a Thermo Scientific TSQ Altis mass spectrometer. Data acquisition employed selected reaction monitoring transitions optimized for each dye, and processing was performed using Thermo Scientific TraceFinder software.

Used Instrumentation

• Thermo Scientific VeriSpray PaperSpray Ion Source with Plate Loader
• Thermo Scientific TSQ Altis Triple Quadrupole Mass Spectrometer

Main Results and Discussion

Analysis time per sample was under two minutes, enabling high sample throughput. The method achieved lower limits of quantification between 0.2 and 2 ppb across all twelve dyes, with no significant differences between fresh and frozen salmon matrices. Calibration curves exhibited excellent linearity (R² > 0.98), and precision and accuracy at the LLOQ met acceptance criteria (<15% RSD, <20% deviation). Comparison with acetonitrile standards indicated minimal matrix suppression, confirming the effectiveness of the QuEChERS cleanup.

Benefits and Practical Applications

• Extremely fast turnaround (≤2 minutes per sample) suitable for high-throughput screening.
• Minimal sample handling reduces labor and solvent costs.
• Low detection limits enable compliance with stringent regulatory thresholds.
• Robust performance in complex food matrices without extensive cleanup.

Future Trends and Opportunities

• Expansion to additional veterinary drugs and food matrices for broader surveillance.
• Integration with automated data processing and reporting platforms to streamline workflows.
• Combination with ambient ionization techniques for on-site or port-of-entry screening.
• Development of portable mass spectrometry systems for field-based analysis.

Conclusion

This paper-spray MS approach provides a rapid, sensitive, and reliable method to quantify veterinary dyes in salmon. Its minimal sample preparation and high throughput make it a valuable tool for routine monitoring in food safety laboratories, ensuring compliance with regulatory standards.

References

1. European Commission Decision of 12 August 2002 implementing Council Directive 96/23/EC concerning the performance of analytical methods and the interpretation of results.
2. CFR - Code of Federal Regulations Title 21, Food and Drugs, Chapter I—Food and Drug Administration Department of Health and Human Services Subchapter E – Animal Drugs, Feeds, and Related Products.
3. George E., Dang V., Borts D., Yang C., Beck J. Multi-class Veterinary Drug Screening and Quantitation with a Comprehensive Workflow: The VetDrugs Explorer. Poster, ASMS 2019.