Veterinary Drug Detection in Pork and Milk - Using an Ultivo LC/TQ with a standard ESI ion source

Significance of the topic

Monitoring veterinary drug residues in animal-derived foods is essential to ensure consumer safety, regulatory compliance, and quality control. Sensitive and rapid analytical methods are required to detect compounds at or below maximum residue limits (MRLs) across diverse matrices such as pork and milk.

Study objectives and overview

This study aims to develop a 10-minute quantitative LC/MS method for twelve regulated veterinary drugs in pork and milk. The method evaluates sensitivity, precision, linearity, and recovery at levels up to five times the MRL using Agilent 1260 Infinity II Prime LC coupled to an Ultivo triple quadrupole with electrospray ionization.

Methodology and instrumentation

Sample preparation:

• Weigh 2 g of sample (milk or pork) and freeze until use.
• Add EDTA solution and extract with acetonitrile containing formic acid and DMSO.
• Shake, centrifuge, and collect supernatants.
• Pork extracts cleaned with Captiva EMR–Lipid cartridges for selective lipid removal.

Instrumentation:

• Agilent 1260 Infinity II Prime LC: Poroshell 120 EC-C8 column (2.1×100 mm, 2.7 μm), 0.35 mL/min flow, 0.2% formic acid in water (A) and 0.5 mM ammonium fluoride in methanol (B) gradient, 9-minute run.
• Agilent Ultivo LC/TQ with ESI source: optimized gas temperature, flow, nebulizer pressure, capillary voltage, dynamic MRM transitions for each compound.
• Data acquired and processed with MassHunter Quantitative Analysis B.09.

Main results and discussion

All twelve drugs were quantified at 1/2 MRL with RSD <14%, and most at 1/10 MRL, with strong signal-to-noise ratios. Calibration curves exhibited excellent linearity (R2 >0.98) over the tested range (1/10 to 5× MRL). Recoveries ranged from 60 to 120% except for streptomycin and dihydrostreptomycin, which showed lower extraction efficiency but remained detectable at regulatory levels. The method demonstrated robust performance in both high-fat and aqueous matrices.

Benefits and practical applications of the method

• Rapid 10-minute analysis suitable for high-throughput screening.
• Meets or exceeds global regulatory sensitivity requirements.
• Simple maintenance and intuitive operation of the Ultivo system.
• Effective cleanup of complex matrices using Captiva EMR–Lipid cartridges.

Future trends and potential applications

Integration of isotopically labeled internal standards to improve quantitation of low-recovery analytes; extension to additional veterinary drugs and food matrices; adoption of automated sample preparation; coupling with UHPLC for further time savings; and advanced data analytics with machine learning for automated result interpretation.

Conclusion

The presented Ultivo LC/TQ method with ESI source delivers a fast, precise, and sensitive workflow for veterinary drug residue analysis in pork and milk, fully compliant with global MRL regulations and suited for routine quality control laboratories.

References

1. U.S. FDA 21 CFR Parts 514 and 558, FDA-2010-N-0155.
2. European Commission Regulation proposal 2014/0257 (COD) on veterinary medicinal products.
3. Ministry of Agriculture, China Announcement No.235, 2002.
4. Health Canada List of Maximum Residue Limits for Veterinary Drugs in Foods, 2017.
5. Zhao L; Lucas D Multiclass Veterinary Drug Analysis in Beef Using Agilent Captiva EMR–Lipid Cartridge Cleanup and LC/MS/MS. Agilent Technologies Application Note, 2017.