Quantitative Screening of Multiresidue Veterinary Drugs in Milk and Egg Using the Agilent 6495C Triple Quadrupole LC/MS

Significance of the topic

The monitoring of veterinary drug residues in milk and eggs is critical to ensure consumer safety, comply with regulatory maximum residue limits, and maintain public confidence in dairy and poultry products. Multi-residue methods are needed to detect a wide range of compounds at trace levels in complex, high-fat and protein-rich matrices.

Study objectives and overview

This work evaluates an end-to-end screening protocol using the Agilent Comprehensive Veterinary Drug dMRM Solution on the Agilent 6495C triple quadrupole LC/MS for the quantitative analysis of 210 veterinary drug residues in milk and egg samples. Key performance parameters assessed include limits of detection and quantitation, calibration linearity, method accuracy, precision, recovery, repeatability, matrix effects, and long-term robustness.

Methodology and instrumentation used

Sample preparation combined an aqueous extraction with lipid removal via Agilent Captiva EMR-Lipid cartridges on a positive pressure manifold. Cleaned extracts were separated on an Agilent 1290 Infinity II system using a Poroshell 120 EC-C18 column and a gradient of aqueous ammonium formate/formic acid and acetonitrile/methanol. Detection employed the Agilent 6495C triple quadrupole MS with Jet Stream ion source in dynamic multiple reaction monitoring (dMRM) mode. Data acquisition and processing used Agilent MassHunter software.

Main results and discussion

• Over 93% of analytes in milk achieved limits of detection ≤1 µg/kg and limits of quantitation as low as 0.05 µg/kg; equivalent sensitivity was observed in eggs.
• Calibration curves for all 210 targets were linear from the LOQ to 100 µg/kg with correlation coefficients ≥0.99.
• Method accuracy based on matrix-matched calibration ranged from 87% to 117%; average recoveries for 95% of targets fell within 60%–120% with repeatability ≤15% RSD.
• Retention time stability was excellent (RSD <0.5%); instrument response repeatability remained below 15% RSD.
• Matrix effects were minimal for most compounds, with more than 95% of targets showing suppression/enhancement between 75% and 125%.
• Robustness testing over 400 continuous injections of a system suitability mix demonstrated sustained peak area reproducibility (RSD <4%) and retention time stability (RSD <0.2%), confirming suitability for high-throughput workflows.

Benefits and practical applications

• An integrated sample preparation and dMRM database minimizes method development time and supports multi-class screening in routine QA/QC laboratories.
• High sensitivity and wide dynamic range ensure compliance with global regulatory standards for milk and egg testing.
• Sustained performance over hundreds of injections enables efficient processing of large sample batches.

Future trends and potential applications

• Application of the workflow to additional food matrices such as meat and seafood.
• Integration with automated sample handling and cloud-based data processing for higher throughput and streamlined reporting.
• Adaptation to high-resolution MS platforms for non-targeted screening and suspect screening of emerging contaminants.

Conclusion

The Agilent dMRM workflow on the 6495C triple quadrupole LC/MS provides a reliable, sensitive and robust solution for the quantitative screening of 210 veterinary drug residues in milk and egg. Its strong analytical performance and high-throughput capacity support routine food safety monitoring and regulatory compliance.

References

• Joseph S et al. An end-to-end workflow for quantitative screening of multiresidue veterinary drugs in meat using the Agilent 6470 Triple Quadrupole LC/MS. Agilent Technologies Application Note, 2020.
• Joseph S et al. Quantitative screening of multiresidue veterinary drugs in seafood using the Agilent 6470 Triple Quadrupole LC/MS. Agilent Technologies Application Note, 2020.
• AOAC. Screening and identification method for regulated veterinary drug residues in food, Version 7, June 2018.
• US FDA. Code of Federal Regulations Title 21, Part 556: Tolerance of Residues in New Animal Drugs in Food, April 2019.
• US FSIS. Chemical contaminants of public health concern used by the Food Safety and Inspection Service, 2017.
• EU Commission Regulation (EU) No 37/2010 on pharmacologically active substances and their classification regarding MRLs.
• Agilent. Comprehensive Veterinary Drug dMRM Solution Workflow Guide (G5368AA), 2021.
• Lehotay SJ. Utility of the Summation Chromatographic Peak Integration Function. LCGC North America, June 2017, 35(6), 391.
• AOAC. Guidelines for Standard Method Performance Requirements. AOAC Official Methods of Analysis, Appendix F, 2016.