Screening 36 Veterinary Drugs in Animal Origin Food by LC/MS/MS Combined with Modified QuEChERS Method

Importance of the Topic

Ensuring food safety by monitoring veterinary drug residues in animal-derived products is critical to protect public health and comply with regulatory limits. Sensitive and rapid analytical methods enable reliable screening of multiple drug classes at trace levels across diverse food matrices.

Objectives and Study Overview

This study introduces a modified QuEChERS extraction combined with LC/ESI-MS/MS using dynamic multiple reaction monitoring (DMRM) for simultaneous screening of 36 veterinary drugs—including sulfanilamides, macrocyclic lactones, quinolones, and clopidols—in meat, milk, egg, and honey. The goal was to optimize sample preparation and chromatographic parameters to achieve satisfactory recoveries and detection limits in line with maximum residue limits (MRLs).

Methodology and Instrumentation Used

• Modified QuEChERS extraction: 4 g Na₂SO₄ and 1 g NaCl salts with 1% acetic acid in acetonitrile and 4 mL water addition for partitioning.
• Dispersive-SPE cleanup: 50 mg PSA, 150 mg C18EC, and 900 mg Na₂SO₄ to remove proteins, lipids, and residual water.
• Instrumental setup: Agilent 1260 HPLC with ZORBAX Eclipse Plus C18 column (3 × 100 mm, 1.8 µm), Agilent 6460 Triple Quadrupole LC/MS with ESI source and DMRM acquisition.
• Chromatographic conditions: 15-minute gradient at 0.5 mL/min, column at 30 °C, 5 µL injection volume.

Main Results and Discussion

The optimized method achieved separation of all 36 analytes within 9 minutes and detection limits compliant with regulatory MRLs. Average recoveries exceeded 50% for all drug classes across meat, milk, egg, and honey. Substituting MgSO₄ with Na₂SO₄ and using acetic acid improved extraction efficiency for sulfanilamides and macrocyclic lactones, while dispersive-SPE with PSA and C18EC effectively reduced matrix interferences. DMRM acquisition provided high sensitivity and selectivity.

Benefits and Practical Applications

• Rapid, high-throughput workflow minimizing analysis and sample preparation time.
• Cost-effective and scalable for routine QA/QC laboratories.
• Applicable to a wide range of animal-origin food matrices.
• Off-the-shelf QuEChERS kits simplify method implementation.

Future Trends and Potential Applications

Future developments may include integration with high-resolution mass spectrometry for non-targeted screening, automation of QuEChERS workflows, combined pesticide and drug residue analysis in a single run, and application of machine-learning algorithms for automated data processing and interpretation.

Conclusion

The modified QuEChERS-LC/MS/MS method provides robust, sensitive, and efficient screening of veterinary drug residues in animal-origin foods, meeting regulatory requirements and streamlining routine food safety monitoring.

Reference

Adapted from Agilent application note 5991-0013EN detailing the validated modified QuEChERS and LC/MS/MS method for screening 36 veterinary drugs.