Determination of Sulfonamides in Commercial Veterinary Formulations by CE-MS/MS

Significance of the Topic

Sulfonamide antibiotics are extensively used in veterinary medicine, requiring accurate analytical methods to ensure product safety and compliance. Capillary electrophoresis coupled with tandem mass spectrometry (CE-MS/MS) provides high separation efficiency, low reagent use, and rapid analysis, making it ideal for monitoring these compounds in complex formulations.

Objectives and Overview of the Study

This work aimed to develop and validate a CE-MS/MS method for the simultaneous determination of four sulfonamides—sulfamethazine, sulfamethizole, sulfachloropyridazine, and sulfadimethoxine—in commercial veterinary products, focusing on speed, sensitivity, and minimal sample preparation.

Methodology and Instrumentation

Samples were homogenized in methanol, diluted 1:1 with water/methanol, and filtered. Sulfathiazole served as an internal standard. Separation was performed on an Agilent 7100 CE system with a 75 µm i.d. PVA-coated capillary (55 cm) using 0.5 M acetic acid (pH 2.5) at 28 kV and 25 °C, with a 12 s hydrodynamic injection (50 mbar). The sheath liquid was 10× diluted BGE in water/methanol (50:50 v/v) at 5 µL/min. Detection employed an Agilent 6430 MS in positive ESI with optimized MRM transitions for each analyte.

Main Results and Discussion

All sulfonamides were baseline separated within 6 min. Calibration was linear from 50 to 500 µg/L (R² > 0.995), with LODs < 2.7 µg/L and LOQs < 9 µg/L. Precision (RSD) was < 5.3%. Analysis of seven commercial formulations yielded concentrations matching label claims, with t-test values below the critical threshold at 95% confidence.

Benefits and Practical Applications

The method is rapid (< 6 min), uses minimal sample and reagent volumes, and requires no additional cleanup. Its high selectivity and sensitivity make it suitable for routine quality control of veterinary pharmaceuticals and potential residue screening in food and environmental matrices.

Future Trends and Opportunities

Future work may extend the approach to other veterinary drugs and metabolites, integrate automated sample preparation for high throughput, refine capillary coatings for enhanced robustness, and develop portable CE-MS systems for on-site testing in veterinary and food safety contexts.

Conclusion

The validated CE-MS/MS method offers a fast, accurate, and selective tool for quantifying key sulfonamides in commercial veterinary formulations, supporting quality assurance and regulatory compliance.

Reference

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