Veterinary Drug Detection in Pork and Milk Using a Small, Innovative Triple Quad with an ESI Source

Importance of the topic

Veterinary drugs are routinely administered to livestock to prevent disease, control parasites, and promote growth. Residues of these compounds in meat and milk pose a public health concern and must be monitored to ensure compliance with global regulatory limits. Reliable analytical methods are essential for food safety testing and regulatory enforcement.

Objectives and study overview

This study demonstrates the quantitation of twelve regulated veterinary drugs in pork and milk using an Agilent 1260 Infinity II Prime UHPLC coupled to an Ultivo Triple Quadrupole mass spectrometer with an electrospray ionization (ESI) source. Target levels correspond to half the maximum residue limit (MRL) as defined by US, Codex, China, and Canadian standards. The method was evaluated for recovery, precision, sensitivity, and linearity.

Methodology and instrumentation

• Sample preparation for milk: 2 g of 2% organic milk fortified with EDTA, extracted with acetonitrile/formic acid/DMSO, vortexed, centrifuged, and directly transferred to LC vials.
• Sample preparation for pork: 2 g ground pork treated with EDTA, homogenized, extracted with acidified acetonitrile, centrifuged, cleaned using Captiva EMR–Lipid cartridges, and eluted into LC vials.
• UHPLC conditions: Poroshell 120 EC-C8 column (2.1 × 100 mm, 2.7 μm), 40 °C, 0.350 mL/min flow, mobile phases of 0.2% formic acid in water (A) and 0.5 mM ammonium fluoride in methanol (B), gradient from 2% to 100% B over 7 min, total run time 10 min.
• MS parameters: Agilent Ultivo Triple Quad MS with ESI; gas temperature 325 °C, gas flow 8 L/min, nebulizer 40 psi, capillary voltage 2000 V, cycle time 500 ms.

Key results and discussion

Chromatograms at half-MRL spiking levels showed clear separation and strong signal for all analytes. Method recoveries ranged from 60% to 120% for most compounds; dihydrostreptomycin and streptomycin exhibited lower recoveries due to high polarity. Precision at the lowest testing levels (½ MRL or 1/10 MRL) yielded relative standard deviations below 14%. Signal-to-noise ratios at 1/10 MRL were high for several analytes, and calibration curves (1/10 to 5× MRL) demonstrated linearity with R²>0.98.

Benefits and practical applications

This workflow provides a rapid, robust, and fit-for-purpose solution for routine screening and quantitation of veterinary drug residues in regulatory and quality-control laboratories. The combination of ESI sensitivity and lipid cleanup enables reliable detection at or below regulatory thresholds.

Future trends and potential applications

Advancements may include broadening analyte panels, adopting alternative ionization techniques to enhance sensitivity, developing dedicated extraction protocols for highly polar compounds, and integrating automation for higher throughput. Emerging mass spectrometry platforms and data-analysis tools will further streamline veterinary drug monitoring.

Conclusion

The Agilent Ultivo LC/TQ with ESI source successfully met global regulatory requirements for veterinary drug residues in pork and milk, delivering excellent precision and sensitivity. Captiva EMR–Lipid cartridges provided effective matrix cleanup, supporting method robustness for routine compliance testing.

Instrumentation used

• Agilent 1260 Infinity II Prime UHPLC
• Poroshell 120 EC-C8 column (2.1 × 100 mm, 2.7 μm)
• Agilent Ultivo Triple Quadrupole MS with ESI source
• Agilent Captiva EMR–Lipid 6 mL, 600 mg cartridges

References

1. Department of Health and Human Services, Food and Drug Administration, 21 CFR Parts 514 and 558, FDA-2010-N-0155.
2. European Commission, Proposal for a regulation on veterinary medicinal products, 2014/0257 (COD).
3. Ministry of Agriculture, China, Maximum Residue Limits in animal derived foods, Announcement No. 235, 2002.
4. Health Canada, List of Maximum Residue Limits for Veterinary Drugs in Foods, August 2, 2017.
5. Limian Zhao and Derek Lucas, Multiclass Multiresidue Veterinary Drug Analysis in Beef Using Agilent Captiva EMR–Lipid Cartridge Cleanup and LC/MS/MS, Agilent Technologies, Application Note 5991-8598EN, 2017.