Recent Advancements in LC-MS/MS Technology for Enabling Improvements in the Multi-residue Analysis of Veterinary Drugs in Food

Significance of the Topic

The detection and quantification of veterinary drug residues in food are critical for ensuring consumer safety and meeting global regulatory standards. Advances in liquid chromatography–tandem mass spectrometry (LC-MS/MS) are driving improvements in multi-residue methods that enable faster, more sensitive, and more reliable screening of diverse compound classes.

Objectives and Study Overview

This study demonstrates the latest enhancements in LC-MS/MS technology to:

• Develop and optimize a streamlined workflow for multi-class veterinary drug analysis in pork matrix
• Evaluate a simplified QuEChERS sample preparation without cleanup
• Implement a solvent sandwich injection technique for improved peak shapes at higher injection volumes
• Leverage an on-line curated mass spectral database to accelerate method development

Methodology and Instrumentation

Sample Preparation and Clean-up:

• 2 g ground pork extracted with 10 mL acetonitrile (QuEChERS approach) without further cleanup
• Centrifugation, freezing, evaporation, reconstitution in MeOH:H2O (1:1) and filtration prior to injection

Chromatography and Mass Spectrometry:

• UHPLC: Thermo Scientific Vanquish Flex Binary system with Accucore VDX column (100 × 2.1 mm, 2.6 µm) at 40 °C
• Gradient: 0.1% formic acid/2 mM ammonium formate (A) and MeOH:ACN +2% water/2 mM ammonium formate (B)
• Injection: Sandwich technique bracketing sample volume with mobile phase A plugs for injection volumes up to 10 µL
• Mass Spectrometer: Thermo Scientific TSQ Quantis Plus triple quadrupole with heated electrospray ionization, fast polarity switching (5 ms), advanced ion optics
• Data Control: Thermo Scientific TraceFinder software for acquisition, review, quantification
• Database: mzCloud for importing optimized precursor/product ions and collision energies

Key Results and Discussion

Calibration and Sensitivity:

• Linearity (10 ppt–5 ppb) with R² > 0.99 for > 95% of compounds
• LOQs mostly < 0.5 ppb in pork extract

Peak Shape Enhancement:

• Sandwich injection improved early-eluting peak symmetry when injecting larger volumes
• Reduction of dead volume and solvent mixing prior to column head sharpened peaks

Fast SRM Acquisition:

• High-density SRM regions processed with short dwell times and stable ion ratios
• Comparable performance between experimentally optimized SRMs and those imported from mzCloud

Benefits and Practical Applications

• Streamlined sample preparation reduces labor and consumables
• Enhanced sensitivity and specificity support compliance with stringent MRL regulations
• Database-driven method setup accelerates development even when standards are scarce
• Robust system suitability checks ensure consistent chromatographic inertness and peak performance

Future Trends and Opportunities

Ongoing innovations in LC-MS/MS promise further gains:

• Integration of high-resolution MS for non-targeted screening of emerging veterinary drugs
• Automated, AI-driven data processing to streamline reporting and reduce manual review
• Expansion of curated spectral libraries to cover novel compounds and metabolites
• Miniaturized and portable LC-MS platforms for on-site residue testing in supply chains

Conclusion

The optimized LC-MS/MS workflow combining simplified QuEChERS extraction, solvent sandwich injection, fast polarity switching, and database-assisted SRM import delivers rapid, sensitive, and reliable multi-residue analysis of veterinary drugs in food matrices. This approach enhances laboratory throughput, ensures regulatory compliance, and lays groundwork for future method expansions.

Reference

1. Screening of 154 Veterinary Drug Residues in Foods of Animal Origin Using LC–MS/MS: First Action 2020.04. Journal of AOAC International.
2. National Food Safety Standard on Maximum Residue Limits for Veterinary Drugs in Foods (GB 31650-2019), Food Safety Standard.